compiled and edited by allison alberts iguanas … · compiled and edited by allison alberts...

Status Survey and Conservation Action Plan

West IndianIguanas

Compiled and edited by Allison Alberts

IUCN/SSC West Indian Iguana Specialist Group

IUCNThe World Conservation Union

Donors to the SSC Conservation Communications Programme andWest Indian Iguanas:


The IUCN/Species Survival Commission is committed to communicate important species conservation infor-mation to natural resource managers, decision-makers and others whose actions affect the conservation of bio-diversity. The SSC's Action Plans, Occasional Papers, news magazine (Species), Membership Directory andother publications are supported by a wide variety of generous donors including:

The Sultanate of Oman established the Peter Scott IUCN/SSC Action Plan Fundin 1990. The Fund supports Action Plan development and implementation; to date, more than 80 grants havebeen made from the Fund to Specialist Groups. As a result, the Action Plan Programme has progressed at anaccelerated level and the network has grown and matured significantly. The SSC is grateful to the Sultanate ofOman for its confidence in and support for species conservation worldwide.

The Chicago Zoological Society (CZS) provides significant in-kind and cash support to the SSC, includinggrants for special projects, editorial and design services, staff secondments and related support services. Themission of CZS is to help people develop a sustainable and harmonious relationship with nature. The Zoo car-ries out its mission by informing and inspiring 2,000,000 annual visitors, serving as a refuge for species threat-ened with extinction, developing scientific approaches to manage species successfully in zoos and the wild, andworking with other zoos, agencies, and protected areas around the world to conserve habitats and wildlife.

The Council of Agriculture (COA), Taiwan has awarded major grants to the SSC's Wildlife Trade Programmeand Conservation Communications Programme. This support has enabled SSC to continue its valuable techni-cal advisory service to the Parties to CITES as well as to the larger global conservation community. Amongother responsibilities, the COA is in charge of matters concerning the designation and management of naturereserves, conservation of wildlife and their habitats, conservation of natural landscapes, coordination of lawenforcement efforts as well as promotion of conservation education, research and international cooperation.

The World Wide Fund for Nature (WWF) provides significant annual operating support to the SSC. WWF'scontribution supports the SSC's minimal infrastructure and helps ensure that the voluntary network andPublications Programme are adequately supported. WWF aims to conserve nature and ecological processes by:(1) preserving genetic, species, and ecosystem diversity; (2) ensuring that the use of renewable natural resourcesis sustainable both now and in the longer term; and (3) promoting actions to reduce pollution and the wastefulexploitation and consumption of resources and energy. WWF is one of the world's largest independent conser-vation organizations with a network of National Organizations and Associates around the world and over 5.2million regular supporters. WWF continues to be known as World Wildlife Fund in Canada and in the UnitedStates of America.

The Department of the Environment Transport and the Regions (DETR), UK supports a Red List Officer postat the SSC Centre in Cambridge, UK, where the SSC Trade Programme staff are also located. Together withtwo other Government-funded agencies, Scottish Natural Heritage and the Royal Botanic Gardens, Kew, theDETR is also financing a specialist plants officer. Further support for the centre is being offered by two NGOmembers of IUCN: the World Wide Fund for Nature - UK, and Conservation International, US.

Donors to the West Indian Iguana Conservation Action Plan: Denver Zoological Foundation; Durrell WildlifeConservation Trust; Fauna and Flora International; Fort Worth Zoo; Milwaukee County Zoo; Saint LouisZoological Park; Sedgwick County Zoo; Zoological Society of San Diego.


West Indian IguanasCompiled and Edited by Allison Alberts

IUCN/SSC West Indian Iguana Specialist Group

The designation of geographical entities in this book, and the presentation of the material, do not imply theexpression of any opinion whatsoever on the part of IUCN concerning the legal status of any country, territory, orarea, or of its authorities, or concerning the delimitation of its frontiers or boundaries.

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Alberts, Allison (comp. & ed.) (1999). West Indian Iguanas: Status Survey andConservation Action Plan. IUCN/SSC West Indian Iguana Specialist Group.IUCN, Gland, Switzerland and Cambridge, UK. 6 + 111 pp.

2-8317-0456-1

Lesser Caymans iguana, Cyclura nubila caymanensis. (©Glenn Gerber)

Gina Guarnieri, London, UK

The Nature Conservation Bureau Ltd, Newbury, UK.

Information Press, Oxford, UK.

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Contents

Foreword iv

Acknowledgements iv

Executive Summary v

List of Contributors vi

Chapter 1. Conservation Strategy 1Introduction 1Taxonomic Considerations 2Biogeographic Considerations 3Socioeconomic Perspective 3Tropical Dry Forest Ecosystems 7West Indian Iguana Habitat 9Overview of West Indian

Iguana Populations 10Overview of Current Threats 12Overview of Existing

Conservation Measures 12

Chapter 2. Taxonomic Accounts 15Turks and Caicos iguana

(Cyclura carinata carinata) 15Bartsch's iguana

(Cyclura carinata bartschi) 18Jamaican iguana (Cyclura collei) 19Rhinoceros iguana

(Cyclura cornuta cornuta) 22Mona Island iguana

(Cyclura cornuta stejnegeri) 27Andros Island iguana

(Cyclura cychlura cychlura) 31Exuma Island iguana

(Cyclura cychlura figginsi) 32Allen's Cay iguana

(Cyclura cychlura inornata) 34Cuban iguana (Cyclura nubila nubila) 36

Lesser Caymans iguana(Cyclura nubila caymanensis) 41

Grand Cayman iguana(Cyclura nubila lewisi) 45

Anegada Island iguana(Cyclura pinguis) 47

Ricord's iguana (Cyclura ricordi) 51San Salvador iguana

(Cyclura rileyi rileyi) 56White Cay iguana

(Cyclura rileyi cristata) 59Acklins iguana

(Cyclura rileyi nuchalis) 60Lesser Antillean iguana

(Iguana delicatissima) 62

Chapter 3. Action Plan 68Summary of Recommendations 68Priority Projects 69Reintroduction Guidelines 70Translocation to Unoccupied Habitat 75Marking Techniques 77Population Monitoring 79Control of Introduced Species 86Genetic Research Needs 89Captive Management Guidelines

- Cyclura 91Captive Management Guidelines

- Iguana delicatissima 93Education and Ecotourism 95

References 97

Appendix 1 List of Conservation Agenciesand Organizations 107

Appendix 2 Criteria forIUCN Red List Categories 109

iii

Foreword

The idea for this Action Plan was originally conceivedat an international workshop on the biology of WestIndian iguanas carried out in conjunction with theIUCN/CBSG Population and Habitat ViabilityAnalysis for the Jamaican Iguana. Held in Kingstonin 1993, the workshop was attended by field biolo-gists, academic researchers, zoo managers, and gov-ernment policy makers from throughout the WestIndies and abroad. This represented the first time thatso many professionals with a strong interest in the sur-vival of West Indian iguanas had gathered to sharetheir expertise and concerns. As such, it proved to bea valuable forum for beginning to identify and priori-tize the conservation needs of this unique group oflizards.

Much of the background information for this firstedition of the Action Plan was initially compiled for

use in the IUCN/CBSG Conservation Assessment andManagement Plan for Iguanid and Varanid lizards(Hudson et al. 1994). Since the CAMP results werepublished five years ago, this material has been sub-stantially expanded and updated. Regional develop-ment and related habitat disturbance are progressingso rapidly that status estimations for some of the taxainvolved are constantly changing. In light of this, thepresent edition of the Action Plan should be consid-ered a starting point for an evolving process ofreassessment and continuing evaluation. As newinformation becomes available, interested parties arestrongly encouraged to contact the Co-Chairs of theIUCN/SSC West Indian Iguana Specialist Group toensure that subsequent drafts remain as accurate andcomprehensive as possible.

Acknowledgments

This Action Plan could not have been produced with-out the generous financial support of the DenverZoological Foundation; the Durrell WildlifeConservation Trust; Fauna and Flora International; theFort Worth Zoo; the Milwaukee County Zoo; the SaintLouis Zoological Park; the Sedgwick County Zoo;and the Zoological Society of San Diego.

Although many people have generously contributedtheir time, energy, and valuable expertise toward mak-ing this Action Plan as complete and accurate as pos-sible, special recognition is due to two individuals.Rick Hudson has worked closely with me on this pro-ject since its inception. Not only was the initial idea

for undertaking the Action Plan his, but since then hehas continued to provide invaluable guidance and crit-ical support for all aspects of the project. Mark Dayhas been an inspiration in terms of his unflaggingenthusiasm, and was responsible for compiling andediting all the maps and photographs contained in theAction Plan. Many heartfelt thanks to all who madethe Action Plan possible.

Allison Alberts, July, 1999Center for Reproduction of Endangered SpeciesZoological Society of San Diego

iv

Executive Summary

The West Indian iguanas form a unique group ofspecies inhabiting tropical dry forests throughout theBahamas and the Greater and Lesser Antilles. Theyare among the most endangered of the world's lizards,primarily because much of their fragile island habitathas been eliminated by human development or severe-ly degraded by exotic species (Case et al. 1992;Taboada 1992). Mongooses, dogs, and feral cats preyheavily on juvenile iguanas, and in many areas intro-duced livestock have denuded the native vegetation onwhich iguanas depend (Iverson 1978; Carey 1966,1975). The Jamaican iguana, considered by some tobe the rarest lizard in the world, may number no morethan 100 adults, and several other subspecies of WestIndian iguanas have declined to below 1,500 individ-uals (Blair 1991 a; Alberts 1993). Until recently, theselizards were the largest land animals in the WestIndies, and a dominant ecological force. Because theyare likely to be important seed dispersers for manyendemic plants (Iverson, 1985), the loss of WestIndian iguanas has serious consequences for theecosystems in which they live.

The purpose of this Action Plan is to summarize thecurrent status of wild populations of all West Indianiguanas, including the rock iguanas (genus Cyclura)as well as the Lesser Antillean iguana (Iguana deli-catissima). Each taxon has been ranked as CriticallyEndangered, Endangered, or Vulnerable according toIUCN Red List Criteria (Mace and Lande 1991; Maceet al. 1992; IUCN 1994). The primary threats impact-ing each taxon are identified, and specific actions formitigating those threats are recommended. On thebasis of this information, the Action Plan prioritizesthe conservation projects most urgently needed to helpinsure the survival of each taxon.

The Action Plan is organized into six major sec-tions. Introductory essays on the systematic relation-ships of West Indian iguanas to other iguanid lizards,the biogeography of the West Indies, socioeconomic

history and current issues, the ecology of dry tropicalforest ecosystems, and West Indian iguana habitat arepresented in order to provide a broad context for thematerial that follows. Next, the status of each taxon isreviewed, including current population estimates anda ranking of relative endangerment. This is followedby an overview of major threats and existing conser-vation measures. Individual species/subspeciesaccounts follow, providing more detailed informationon distribution, status of wild populations, ecologyand natural history, condition of critical habitat,threats to survival, current conservation programs,critical regional conservation initiatives, and specificpriority conservation projects. Recommendations forreintroduction, translocation to unoccupied habitat,population monitoring, control of introduced species,genetic research, captive management, and educationfollow. Finally, a list of national agencies, researchinstitutions, and conservation organizations in thecountries of origin for the taxa covered by the ActionPlan is included.

The West Indian Iguana Action Plan was drafted by27 contributors from nine different countries, with thecommon goal of designing viable conservation strate-gies for the iguanas we have come to care deeplyabout but only begun to understand. It is our collec-tive hope that the plan will not only inspire those inthe scientific community to further study the intrigu-ing biology of these magnificent lizards, but also serveas a strong impetus to government officials, conserva-tion planners, and community leaders to implementimmediate and effective conservation measures ontheir behalf. Iguanas represent a unique and irre-placeable component of West Indian natural heritagethat must be preserved for future generations. To theextent that this Action Plan can help foster anincreased sense of pride and stewardship for iguanasin the people with whom they share the islands, wewill have begun to achieve our mission.

v

List of Contributors

Allison Alberts, Center for Reproduction ofEndangered Species, P.O. Box 120551,Zoological Society of San Diego, San Diego,California 92112 USA

David Blair, Cyclura Research Center,PMB #510, 970 West Valley Parkway,Escondido, California 92025 USA

Michel Breuil, Laboratoire des Amphibiens etReptiles, Musee National d'Histoire Naturelle deParis, 25 rue Cuvier, 75005 Paris, France

Sandra Buckner, Bahamas National Trust,P.O. Box N4105, Nassau, The Bahamas

Fred Burton, National Trust for the Cayman Islands,P.O. Box 31116 SMB, Grand Cayman, Cayman Islands

Ronald Carter, Department of Natural Sciences,Loma Linda University, Loma Linda,California 92350 USA

Bill Christie, Indianapolis Zoo, 1200 W. WashingtonStreet, Indianapolis, Indiana 46222 USA

Scott Davis, Animal Science Department,Klaberg Building, Texas A&M University,College Station, Texas 77843 USA

Mark Day, Fauna and Flora International,Great Eastern House, Tenison Road,Cambridge CB1 2DT, UK

Robert Ehrig, Finca Cyclura, 29770 Mahogany,Big Pine Key, Florida 33043 USA

Miguel Garcia, Bureau of Fisheries and Wildlife,Department of Natural and Environmental Resources,P.O. Box 9066600, San Juan, Puerto Rico 00906

Glenn Gerber, Department of Ecology andEvolutionary Biology, University of Tennessee,Knoxville, Tennessee 37996 USA

William Hayes, Department of Natural Sciences,Loma Linda University, Loma Linda,California 92350 USA

Richard Hudson, Department of Herpetology,Fort Worth Zoo, 1989 Colonial Parkway, Fort Worth,Texas 76110 USA

John Iverson, Department of Biology,Earlham College, Richmond, Indiana 47374 USA

Chuck Knapp, John G. Shedd Aquarium, 1200 SouthLake Shore Drive, Chicago, Illinois 60605 USA

James Lazell, The Conservation Agency,6 Swinburne Street, Conanicut Island,Rhode Island 02835 USA

Ariel Lugo, International Institute of TropicalForestry, USDA Forest Service, P.O. Box 25000,Rio Piedras, Puerto Rico 00928

Numi Mitchell, The Conservation Agency,Branch Office, 67 Howland Avenue, Jamestown,Rhode Island 02835 USA

Richard Montanucci, Department of BiologicalSciences, 132 Long Hall, Box 341903, ClemsonUniversity, Clemson, South Carolina 29634 USA

Jose Ottenwalder, UNDP/GEF Dominican RepublicBiodiversity Project, United Nations DevelopmentProgram, P.O. Box 1424, Mirador Sur,Santo Domingo, Dominican Republic

Antonio Perera, Centro Nacional de AreasProtegidas, Calle 18A No. 4114, Miramar Playa,Ciudad Habana, Cuba

Steve Reichling, Herpetarium/Aquarium,Memphis Zoo and Aquarium, 2000 Galloway,Memphis, Tennessee 38112 USA

Jack W. Sites, Jr., Department of Zoology,Brigham Young University, Provo, Utah 84602 USA

Peter J. Tolson, Department of Conservation andResearch, Toledo Zoological Society, 2700 Broadway,Toledo, Ohio 43609 USA

Peter Vogel, Department of Life Sciences,University of the West Indies, Mona Campus,Kingston 7, Jamaica

Thomas Wiewandt, Wild Horizons, Inc.,P.O. Box 5118, Tucson, Arizona 85703 USA

vi

Chapter 1. Conservation Strategy

Introduction

Only 60 of the 3,000 species of lizards living todayattain an adult body mass greater than one kilogram.Although large lizards represent only 2% of all lizardspecies, they account for 60% of lizard species con-sidered threatened or endangered. Indigenous largelizards are often the predominant vertebrates withrespect to biomass in undisturbed environments (Case1982; Iverson 1979; Dugan 1980; Pianka 1986;Phillips 1995). However, in degraded habitats, popu-lations of these lizards may be severely depleted rela-tive to expected carrying capacity. Biomass estimatesof healthy iguana populations often exceed 20kg/ha,an order of magnitude greater than reported for mam-malian herbivores. The absence or reduction of theselizards unquestionably alters the ecosystems of whichthey are a part.

The islands of the West Indies form the principalarchipelago of the neotropics. As a result of pro-longed geographical isolation, native mammal specieson these islands are few, consisting mainly of bats androdents. Birds, reptiles, and amphibians, however,have undergone significant radiations and comprisethe majority of the vertebrate biodiversity of the WestIndies. Most of the large islands are densely populat-ed by people and suffer from environmental degrada-tion and the ill effects of introduced species (Case andBolger 1991). As a result, a significant number oftaxa, including many endemics, have disappeared orare on the brink of extinction.

The iguanas of the West Indies (Cyclura andIguana delicatissima) are among the largest and mostimpressive members of the family Iguanidae, yet theyare also the rarest. All taxa are currently protectedunder the Convention on International Trade inEndangered Species (CITES), with five of 17 formsconsidered to be Endangered, and eight CriticallyEndangered, by the World Conservation Union (IUCN1996). Although exploitation of West Indian iguanasbegan long ago by native peoples, it was probably notuntil the arrival of Europeans that iguana populationsbegan their most precipitous decline. In addition tothe habitat loss and degradation inevitably resultingfrom large scale human settlement, the commensalspecies that accompanied immigrants to the islandshave had a devastating impact on iguanas and theecosystems they inhabit. Dogs, cats, pigs, and ratsprey on iguanas and their eggs, while goats, sheep,cattle, and other livestock have contributed to the

deterioration of the unique plant communities onwhich iguanas and other native species depend. Theintroduction of the Indian mongoose (Herpestesjavanicus [=aurounctatus]), ostensibly to controlrats, has instead resulted in predation of untold num-bers of native species, including juvenile iguanas.

Typical dry tropical forest habitat for iguanas atGuantanamo Bay, Cuba.

West Indian iguanas inhabit dry subtropical thornforest regions in the Bahamas, the Virgin Islands, andthe Greater and Lesser Antilles. While Cyclura areterrestrial, depending heavily on the presence of rockycrevices to serve as retreats, Iguana delicatissima isprimarily arboreal. Both require sandy areas withappropriate soil conditions in which to lay their eggs.Most species live for multiple decades and may takeseveral years to reach sexual maturity. Social organi-zation ranges from systems in which adult males arehighly aggressive and territorial to large groups whichappear to coexist peacefully. Mating is seasonal, witha single clutch per year, usually laid in May or June.Raptors, cuckoos, herons, and colubrid and boidsnakes are the only natural predators of West Indianiguanas, and then usually only of juveniles.

West Indian iguanas are almost exclusively herbiv-orous, consuming an unappreciated diversity of vege-tation types. The Turks and Caicos iguana is knownto feed on at least 58 plant species (Iverson 1979;Auffenberg, 1982), the Cuban iguana on 25 species(Perera 1985a), the Grand Cayman iguana on 45species (Burton and Gould, in preparation), the LesserCaymans iguana on over 40 species (G. Gerber,unpublished data), and the Mona Island iguana on 71species (Wiewandt 1977). Because these lizards donot chew appreciably (Throckmorton 1976), and

1

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llison Alberts

digestion of plant foods is incomplete, seeds passingthrough the digestive tract are probably still capable ofgerminating (Iverson 1985; F. Burton and S. Gould,unpublished data). For this reason, West Indian igua-nas are likely to be important seed dispersers for manyendemic plants.

The sections that follow are designed to provide abroad historical context for the specific conservationactivities recommended later in the Action Plan.Taxonomic issues relevant to West Indian iguanas arediscussed, including the need for further phylogeneticstudies to help establish conservation priorities.Effects of climate change, ecosystem-level processes,and past and modern human disturbance are coveredas well. Finally, an overview of the current status ofWest Indian iguanas is provided, together with a sum-mary of existing threats and conservation measuresfor each taxon.

Taxonomic Considerations

By Jack W. Sites, Jr.

Several recent hypotheses have been presented regard-ing relationships among the living genera of large her-bivorous lizards collectively known as iguanas (deQueiroz 1987; Frost and Etheridge 1989; Norell andde Queiroz 1991; but see Lazell 1989, 1992). As aworking hypothesis, the family Iguanidae is here con-sidered to be restricted to this radiation, which con-tains seven genera (Amblyrhynchus, Conolophus,Ctenosaura, Cyclura, Iguana, Dipsosaurus,Sauromalus; eight if Enyaliosaurus is considered dis-tinct from Ctenosaura) indigenous to North and SouthAmerica (de Queiroz 1987; Frost and Etheridge1989), as well as the South Pacific genusBrachylophus. Much attention has been given to thebehavioral and ecological aspects of iguana biology(Burghardt and Rand 1982), but until recently modernsystematic studies have lagged behind (Etheridge1982). Consequently, the biogeographic history andevolutionary relationships among these genera remainpoorly understood and controversial. In addition tomorphological and chromosomal data collected thusfar, different classes of molecular data hold greatpromise for further resolving iguanid relationships.These approaches might also address some of theobjections raised by Lazell (1989) regarding speciesand generic boundaries within the radiation. Researchis needed to test independently the current definitionsof species and genera recognized on the basis of mor-phological and skeletal characteristics, and to developa well-corroborated phylogenetic hypothesis for the

entire group.About 30 species of iguanas are currently recog-

nized (Burghardt and Rand 1982; de Queiroz 1987).Many are not well defined, especially within the gen-era Ctenosaura and Cyclura, and ideally all should beverified by several genetic markers. The radiation ofrock iguanas throughout the Greater Antilles and theBahamas is among the most diverse within theIguanidae with respect to species numbers recognizedon the basis of morphological criteria. Sampling withmolecular markers to verify species boundaries isespecially important in the West Indies because of theisland distributions of rock iguanas and the extremelycomplex patterns of diversification and geological his-tory in this region (Rosen 1985; Hedges et al. 1992).

The literature on species and their recognition con-tinues to increase, with little apparent consensus onhow to diagnose independently-evolving lineages(Wiley 1978; reviewed by Frost and Kluge 1995).However, a number of operational proposals havebeen offered which avoid the pitfalls of tree-basedcharacter methods (Doyle 1995), with specific guide-lines for their implementation (Avise and Ball 1990;Davis and Nixon 1992; Templeton 1994; Templetonand Sing 1993; Mallet 1995). Under these methods,evaluations of species boundaries become testablehypotheses subject to verification or falsification, apractice that should become standard in future genet-ic studies of iguanas whenever species boundaries arean issue. A concern arises with regard to the use ofmitochondrial DNA markers to address questionsregarding species boundaries (Moritz 1994).Although mtDNAs are known to show substructuringin some geographically widespread iguanid lizards(Lamb et al. 1992), small inbreeding effective popula-tion size may render this approach inadequate fordelimiting species boundaries.

Equally important to the identification of speciesfor determining the taxonomic composition and diver-sity of the Iguanidae is the development of a well-cor-roborated phylogenetic hypothesis for all species andgenera. This will provide not only an evolutionaryand biogeographic context within which specializedecological and behavioral adaptations can be evaluat-ed, but also a measure of the genealogical distinctnessof each species. The latter can contribute to the estab-lishment of conservation priorities on the basis ofoverall measures of taxonomic diversity and evolu-tionary importance (Vane-Wright et al. 1991; Avise1992; Brooks et al. 1992; Stiassny 1992). Sites et al.(1996) recently reconstructed the phylogenetic rela-tionships among living Iguanidae on the basis ofmtDNA sequence and morphological characters, andshowed strong support for monophyly of all generanamed above except Enyaliosaurus.

2

Biogeographic Considerations

By James Lazell

Despite, or perhaps because of, the enormous amountof factual information developed since 1492, the WestIndies remain a region of extreme controversy(Williams 1989). Probably no other tropical realmhas been so extensively studied, but fundamental dis-agreements over the origin of the islands and theirbiota remain. A critical but neglected factor in WestIndian biogeography has been the enormous changein land areas and potential dispersal distances wroughtby sea level fluctuations dependent on glacial andinterglacial climatic cycles. Dramatic sea levelchanges in the region have greatly modified total landarea and in many cases altered dispersal distances byorders of magnitude (Lazell 1996).

As a rough generalization, the West Indian islandstoday surmount banks of rather shallow water whichfall off abruptly at their edges. Not surprisingly, thebiogeographic significance of the banks is largelyreflected in the degree of difference in biotas: islandson the same bank have rather similar, slightly differ-entiated faunas, while islands on separate banks showhigh degrees of endemism (Williams 1969). The WestIndian iguanas form a suite of obviously very closelyallied forms. Hispaniola, the Great Bahama bank, theGreater Puerto Rico bank (Virgin Islands), and theGuadeloupeen archipelago have two forms each, butotherwise there is only one form on any island bank.In general, West Indian iguanas present an overall pic-ture of weak differentiation in which geographicallyintermediate forms are apt to be morphologicallyintermediate (Lazell, 1989). Hybridization betweenforms is known to occur.

Climate change has combined with human distur-bances over the last 4,000 years to alter the WestIndian fauna dramatically. Many mammals, largebirds, and reptiles once occupied a broad array ofislands but are now extinct. It seems that iguanas,however, tolerated these changes well until Europeaninvasion. However, in the last century, and especiallyin the last three decades, changes in iguana popula-tions and ranges have been catastrophic. Teemingpopulations have simply disappeared and animalsonce abundant are now critically endangered.

Iguanas tend to be most common in coastal low-lands, and these areas tend to be covered with ocean-ic limestone formed during times of high sea levelsdating back at least to the Miocene. Limestone, beingporous and often cavernous, drains quickly and pro-vides poor soil compared to volcanic terrain. Iguanasmay be associated with limestone terrains becausethey find security from exotic predators like dogs and

cats in the limestone cavities, and as a result of theirability to survive on soils of very low agriculturalpotential. In the Lesser Antilles, however, Iguana deli-catissima was once abundant on volcanic strata direct-ly adjacent to the sea. It is possible that limestonehabitats are suboptimal for iguanas, and iguana pres-ence there today represents fortuitous survival ratherthan adaptation.

Socioeconomic Perspective

By Jose Ottenwalder

The Wider Caribbean encompasses a vast marine area,bordered by island nations, dependent territories, andcontinental countries. With 36 nations represented, itcomprises the largest number of national jurisdictionsof any similarly sized region in the world. Within theregion, the West Indies consists of 23 island Statesfeaturing a variety of people, cultures and politicalsystems characterized by different types and stages ofeconomic development (Table 1). Although part ofthe Americas, the islands of the West Indies are aunique entity whose history, societies, environment,and general ambiance differ in many significantaspects from those of any found on the LatinAmerican, North American, or European mainland.

The West Indies were the first to encounter the ini-tial thrust of European expansion across the Atlantic.The consequences of the ensuing traffic of plant andanimal species, peoples, diseases, and raw materialsare well known, and include the eventual loss of allaboriginal human populations inhabiting theseislands. In addition, the islands bore the brunt of theEuropean movement towards tropical plantationdevelopment. The region entered a new stage of envi-ronmental change characterized by increased resourceuse, a shift in human-environment relationships, andgreater exposure to outside technologies, a processthat continues to the present. The cumulative effect ofthis history is reflected in widespread ecologicaltransformations. Like most small tropical islands,West Indian ecosystems are environmentally fragileand vulnerable to deforestation, erosion, and conver-sion for development. Reduced area, exposure to hur-ricanes, and the presence of active volcanoes on someislands further compound their social, economic, andenvironmental vulnerability.

Historical perspective of developmentThe historical impact of aboriginal peoples on WestIndian ecosystems is still uncertain. A key question iswhether the native inhabitants of the islands ever

3

achieved high population densities. Proposed figuresfor Hispaniola, the standard demographic referencefor the region, range from 100,000 to 6-8 million(Watts 1987, Keagan 1992). According to Keagan(1992), it is not inconceivable that the Taino popula-tion of Hispaniola reached 1-2 million. Although amatter of continued debate, the total native populationof the West Indies in 1492 could have been more than5.8 million (Watts 1987). Despite this, it is generallybelieved that aboriginal inhabitants did not have a sig-nificant impact on the natural environment, leavingmost mature forests largely untouched. Taino socialand political complexity was based in part on a systemof intensive agriculture, with manioc as a staple, sup-plemented with abundant wild estuarine and marineresources (Wing 1989, Deagan 1995). FollowingEuropean contact, disease, falling birthrates, hardlabor, and even anomie from culture shock decimatedaboriginal populations. By 1576, native peoples hadbeen extirpated on Hispaniola, which was then occu-pied by Spanish, black, and racially mixed popula-tions.

Following early colonization, the region became asource of tropical agricultural commodities. Marketsin Europe and North America were relatively accessi-ble and the slave trade had enormous demographic,social, and environmental consequences. Rapid pop-ulation growth, widespread use of plantation agricul-tural systems after the 17th century, large-scale landclearing for sugar cane, and timber harvesting pro-duced widespread deforestation, erosion, loss of waterresources, and a decline in fertility and productivity(McElroy et al. 1990). As a result, many West Indianislands were deforested early. The forest cover ofPuerto Rico was reduced to 10% of its former rangeby the end of the 19th century, and what remained wasdisturbed and often mixed with coffee understory(Harcourt and Sayer 1996). For the West Indies as awhole, total forest cover remaining in 1920 was only50% (Zon and Sparhawk 1923). Further deforestationfor sugar cane plantations and cattle ranching up untilthe 1970s reduced overall West Indian forest cover to18% (Lugo et al. 1981). While a few island countriesstill presently maintain about 50% of their forestcover, others have lost almost all of it.

The spread of exotic species was another emergingthreat, including both deliberate and unintentionalintroductions of domestic, commensal and, eventual-ly, wild stocks. Prominent among intentional Spanishimports were hogs, cattle, sheep, and goats for food,with horses, donkeys, dogs, and cats also brought in tosatisfy other needs. In the absence of competitors andpredators, feral populations flourished. Free-rangecattle ranching was widespread, developing first in thelowlands, and trade in cattle hides was extensive, with

as many as 200,000 hides exported from Hispaniolaannually prior to the 1580s (Deagan 1995).

In the 200 years following colonization, coastallowland forests were extensively reduced throughconversion to plantations and cattle ranching.Degradation of lowland habitats led to the spread ofsugar cultivation and livestock production to higherelevations. Pressure upon montane forests for subsis-tence agriculture increased between 1880 and 1940following the abolition of slavery. After emancipation(circa 1840), the economic return from sugar cultiva-tion and export plummeted as a result of higher laborcosts and competition from larger producers(McElroy et al. 1990). The consequences of theseeconomic losses spawned a continuous migratorytrend, a demographic shift from the steady populationgrowth maintained since colonial times, the appear-ance of marginal, small-scale farm systems, and a ten-dency for local populations to turn to artisanal fish-eries as a subsistence and largely unregulated com-mercial enterprise (McElroy et al. 1990).

During the early 20th century, the cumulative effectof these environmental changes, as well as the clear-ing of primary and secondary forests, over-browsingby livestock, and continued erosion, habitat destruc-tion, and soil degradation had a strong impact on WestIndian island ecosystems. Widespread depletion ofresources resulted in diminishing productivity forfarming and fishing and a decline in rural employmentand traditional cash crops. These changes resulted inlarge scale and continuing emigration, reduced avail-ability of food and energy at accessible costs, severesectoral imbalances in insular economies, and drasticchanges in land use. A few very large tracts of landbecame consolidated into large-scale export crop andlivestock farms, while a large number of small tractsof land appeared as fragmented and largely non-pro-ductive family farm plots. A shift from production toservice-based economies was stimulated by low-costfood imports and the need to support increasing urbanpopulations and tourists.

Present and future challengesAt present, all West Indian islands have populationdensities that are among the highest in the world,excluding southwest Asia (FAO, 1997) (Table 1).About 72.6% of the total population in the region areconcentrated in Cuba, the Dominican Republic andHaiti, with Hispaniola supporting the highest num-bers. The average annual rate of population increasefor the region is 1.3%, although a few countries areapproaching or below the replacement level.Characterized by high rates of urbanization (WorldResources Institute 1996), the region's population isprojected to increase to about 40 million by the year

4

2000, and to nearly 60 million by 2025. The cos-mopolitan array of peoples representing a variety ofraces, ethnic mixes, languages, and cultures has ham-pered regional integration and implementation ofenvironmentally and socially sustainable develop-ment.

The tourist industry in the West Indies has devel-oped rapidly over the last 40 years, and since the1960s has become the leading economic sector inmany island states. According the World Council onTravel and Tourism, the impact of this industry onWest Indian economies is significant, representingabout 30% of the regional Gross Domestic Product(GDP). Its current estimated annual growth is 35%,contributing strongly to the generation of localemployment. Furthermore, the industry is the leadingprovider of foreign currency income, accounting for76.2% of total capital investment in the region. Therapid expansion of tourism has resulted in escalatingland values, with concomitant increases in populationgrowth and per capita income. With modernization,the traditional rural sector has been reduced and farm-ing and fishing have become marginal activities.Extensive coastal development due to urbanization,industrialization, and tourism has impacted estuaries,mangrove forests, and coral reef ecosystems.Unregulated exploitation has caused widespreaddepletion of formerly abundant traditional subsistencefisheries in the region (FAO 1993). Simultaneously,local populations of highly threatened marine speciessuch as sea turtles and manatees have been drasticallyreduced.

West Indian countries face special challengesbecause of their small size and extreme economic andenvironmental vulnerability. As a result of mountain-ous topography and high population densities, the costof economic and social infrastructure is high. Internalmarkets are small and open to world trade, withexports and imports of goods and services averaging75% of GDP. Most of the islands have traditionallybeen monocrop economies, relying on preferentialtrade arrangements for their main exports.Commercial barriers for West Indian exports to theUS have increased, and the region's export marketsare now threatened by larger trade arrangements (e.g.General Agreement on Trade & Tariffs [GATT], inte-gration of European Common Market, NorthAmerican Free Trade Association [NAFTA]).

Regional economic growth remains constrained bya number of factors, including underdevelopeddomestic financial sectors and infrastructure, lowdomestic saving rate, and associated scarcity of capi-tal for investment. As aid to the region has declined,economic prospects have depended increasingly onprivate sector development to generate growth to com-

pete in the global economy, create jobs, and increaseper capita income. As a result, West Indian economiescontinue to be vulnerable to external changes, partic-ularly trade and financial flows influencing regionalmarkets. Major economic challenges include improv-ing social development, strengthening public finances,reforming financial markets, improving legal and reg-ulatory environments to promote private sector activi-ty, and reforming the public sector to improve gover-nance.

Following the economic stagnation of the 1980s,productivity and exports are currently rising, per capi-ta income is growing, private sector performance isimproving, and inflation continues to decrease.Against this encouraging economic picture, over-crowded and polluted cities, persistent poverty, andthreatened biodiversity stand in stark contrast. In lightof these problems, the region's challenge is to aligneconomic growth with social equity, sustainably man-age biologically diverse areas, and control urban envi-ronmental problems. Achieving these tasks will requireintegration of environmental concerns into investmentprograms and policy frameworks to ensure sustain-ability, and building the institutional capacities to im-plement priority programs and monitor compliance.

Implications for iguana conservationWest Indian iguanas occur primarily in dry foresthabitats in coastal lowlands, where they are vulnera-ble to impacts from human land use and associateddegradation of coastal ecosystems. West Indiannations largely depend on the health and beauty ofcoastal habitats to generate income, particularly fromnature-based tourism. As a result, economic activitiesand human populations are heavily concentratedalong coastal areas. The conservation of coastal bio-diversity in the region is therefore linked not only tosocial, cultural, and political conditions, but also toeconomic realities and prevailing financial con-straints.

Environmental problems and priorities affectingcoastal biodiversity in the region are complex anddiverse. Causes of destruction, fragmentation, anddegradation of coastal ecosystems include: urbaniza-tion; uncontrolled development of tourism and indus-trial infrastructure; coastal modification through con-struction, mining, filling and dredging; deforestation;fuelwood and hardwood extraction; soil erosion andwatershed degradation; demand for food and rawmaterials; retention of freshwater flow and withdraw-al of water for irrigation; sewage, industrial, and solidwaste disposal; agrochemical runoff; operational andaccidental spills. In addition, introduced mammalianherbivores and carnivores in coastal areas have provenhighly detrimental to native plant and animal biodi-

5

versity, including iguanas and their habitats.A number of authors (in Harcourt and Sayer 1996)

recently concluded that most of the natural lowlandforests of West Indies have already been devastated.Total forest cover for the West Indies in 1995 was esti-mated at 19.4% of total land area, with an averageannual deforestation rate of 1.7% for the period 1990-95 (Table 1). Major causes of forest degradationinclude habitat destruction and clearing of land foragriculture, extraction of forest products for timber,fuelwood and charcoal, and forest fires, often origi-nating from subsistence agriculture.

Although moist forests have suffered extensively,some relatively large tracts of mangrove and coastalxeric communities remain less impacted. However,little information exists about the total remainingextent and present status of West Indian dry forestcommunities (World Wildlife Fund 1996). Accordingto the World Conservation Monitoring Centre 1997Forest Database, 14,802 km2 of dry forest remains,including deciduous/semideciduous broadleaf forest(7,734 km2), thorn forest (1,206 km2), sclerophyllousdry forest (5,822 km2), and sparse trees/parkland (40km2). A recent regional analysis of geographic prior-ities for biodiversity conservation in Latin Americaand the Caribbean ranked Caribbean ecoregion asendangered and its xeric communities as regionallysignificant for their biological value (BiodiversitySupport Program et al. 1995).

According to the recent IUCN/SSC Status Surveyand Conservation Action Plan for Cactus andSucculent Plants (Oldfield 1997), 75% of cactus andsucculent plant species surveyed are endemic to theWest Indies (actual percentage likely even higher asBurseraceae, Begoniaceae, Piperaceae, Rubiaceae,Urticaceae, aroids, and orchids are not covered).While the taxonomic status of West Indian succulentsremains poorly known, new species continue to bediscovered (Areces-Mallea 1997). In general, thelargest number and highest density of endemics occurin arid coastal areas and other dry habitats, which alsosupport West Indian iguanas. Vegetation categorieslisted in Oldfield (1997) for West Indian succulents(sandy beaches; strand littoral scrub and low forest;saline flats; rock pavement vegetation; dry limestoneshrubwoods; semi-desert cactus scrub; dry serpentineshrubwoods) generally also support West Indian igua-nas. Not unexpectedly, many threats identified forthese plant communities are similar to those affectingiguanas (clearing for agriculture, urbanization andtourism, mining and quarrying, collecting, introducedspecies, and natural disasters).

Sustainable forest management in the West Indiesis complicated due to the great diversity of foresttypes, making it difficult to develop successful man-

agement techniques that can be applied over largeareas (Lugo 1990). Furthermore, competition for flatland is intense and the price of coastal land has soaredduring the last two decades. Conservation of WestIndian iguanas is clearly linked to future preservationof dry coastal habitats. For some countries like Haiti,it may already be too late to save remaining forests(Table 1). However, many countries have passed newlaws and regulations pertaining to natural forest man-agement and use that reflect the key social, environ-mental, and economic roles forests play.

ConclusionsRegional success in managing coastal ecosystems isultimately rooted in the ability of individual WestIndian states to build their internal capacities andcommit wholeheartedly to a regional approach. In thepast, mostly because of the lack of political support,integration efforts have failed. Notwithstanding theseand other obstacles, it is heartening to see a great dealof functional cooperation being practiced daily, aprocess which is expanding. Over the ensuingdecades, it may well be economic issues, especiallythose of tourism, commercial trade markets and fish-eries, rather than political issues that will effectivelyintegrate the region. In addition, promotion of basicand essential linkages at the physical, cultural, andinstitutional levels will be critical to integratingphilosophies and activities among countries. Parallelimplementation of a comprehensive coastal manage-ment policy to preserve and protect the remarkablebiodiversity resources of the West Indies will beessential. Participatory management experiments,which allow local stakeholders to play a leading rolein identifying priorities, problems, and managementstrategies, are vital to national planning efforts andcapacity building. Successful implementation ofthese actions can then effectively complement theestablishment of a regional consensus on conservationpriorities, standards, and strategies (Ottenwalder1996).

Below is a set of general recommendations from asocioeconomic perspective for achieving the conser-vation goals and activities outlined herein.

6

• Apply ecosystem management principles toconservation efforts.• A range of actors including local communities,government institutions, and private organiza-tions, including non-governmental organizationsand the tourist sector, should be involved in theplanning and implementation of conservationand management activities, as appropriate.• Develop and promote sustainable management

of dry forest habitats in cooperation with localcommunities.• Maximize overall biodiversity conservation byintegrating efforts at the species, community, andecosystem levels.• Enhance impact and effectiveness of efforts bycooperating with other IUCN Commissions andSSC Specialist Groups active in the region, inorder to pursue an integrated, multi-disciplinaryapproach.• Prioritize and incorporate coastal habitat pro-tection in tourism development planning, makinguse of tools such as environmental impactassessments, and strengthening relevant legisla-tion.• Emphasize capacity building and strengtheninglocal conservation institutions, for both govern-ment agencies and non-governmental organiza-tions.• Promote regional cooperation and integrativeapproaches among and between West Indianstates.

Tropical Dry Forest Ecosystems

By Ariel Lugo

Tropical and subtropical dry forest ecosystems occurin frost-free climates from lowlands to lower montaneregions where potential evapotranspiration exceedsprecipitation on an annual basis (Holdridge 1967).Generally, they occur in environments with meanannual rainfall ranging from 1000 to 2000mm andmean annual biotemperatures of 12°C and above.Forest stature, primary productivity, and tree speciesrichness increase with increasing rainfall (Murphyand Lugo 1986a; 1995). Dry forests are seasonalforests, experiencing wet and dry periods. Air tem-peratures are usually high and relative humidities low.The result is that dry forest plants have multiple adap-tations to dry conditions, including drought avoidanceand resistance through a variety of morphological andbehavioral characteristics (Lugo et al. 1978; Medinaand Cuevas 1990).

Tropical dry forests occur on substrates rangingfrom nutrient-rich alluvial soils to nutrient-poor rockoutcrops. They can occur on volcanic, limestone, orultramorphic rocks, with soil textures ranging fromsandy to clay, rocky, or organic. Substrate type cangreatly exacerbate the water limitations of dry tropicalforest climates. If soils are droughty and have lowwater holding capacity, vegetation may acquire a

greater xeromorphic aspect than expected.Conversely, in locations where soils store water wellor where water is channelized (as in valleys orcanyons), vegetation may acquire great stature andbiomass (Murphy and Lugo 1990; 1995). Tropicaldry forest vegetation is generally water rather thannutrient limited (Lugo and Murphy 1986).

West Indian dry forests are characterized by small-er stature and biomass, lower biodiversity and produc-tivity, and more seasonal tree growth, reproductivecycles, and organic matter turnover than forests inareas of higher and less seasonal rainfall (Murphy andLugo 1995). Leaf and litterfall is seasonal (Lugo et al.1978; Lugo and Murphy 1986; Cintron and Lugo1990). Soils can have high organic matter, high pH,and low bulk density (Brown and Lugo 1990). Soilnutrient content is relatively high but with low phos-phorus availability to plants (Lugo and Murphy 1986).Animal activity can be highly seasonal as well.Termites are important in the decomposition andturnover of dead wood. Ants and other soil organismsturnover inorganic soil, transport seeds for great dis-tances, and participate in a complex biotic web thatprocesses large quantities of organic matter.

Tropical dry forests support a large fraction of thehuman population in the tropics, and as a result, areunder intense pressure (Murphy and Lugo 1986a).Because dry climates are preferred over very wet cli-mates in the tropics, large population concentrationsoccur in dry forest life zones. The result is that tropi-cal dry forests not only provide space for the expand-ing human population, but are also used intensively asa source of fuelwood and charcoal. Grazing animalsare also often allowed to roam free through dryforests.

The net result of human activity in this life zone isthe serious degradation or disappearance of dryforests in most tropical regions. Because successionis usually slow in these forests, chronic human useresults in deforestation and modification of vegetationcover. Usually, degraded stands lose their understoryto grazing animals, trees are repeatedly harvested andresprout as multiple small stems, the canopy isopened, and soils are exposed to erosion (Murphy etal. 1995). In cases of extreme use, fire is introduced.Despite these problems, the current condition of dryforests opens the opportunity for restoration and man-agement. Tropical dry forests are resilient in terms oftheir ability to root and stem sprout, a characteristicthat can be used to rehabilitate forests and restore bio-mass (Murphy and Lugo 1986b; Murphy et al. 1995;Murphy and Lugo 1995). Experience with tree plan-tations shows promise provided they are managedcarefully (Lugo et al. 1990; Wang et al. 1991).

7

Table 1. Basic socioeconomic and environmental indicators for the insular Caribbean.

8

Country

Antigua and BarbudaBahamasBarbadosBermuda(British Virgin Islands)(Cayman Islands)CubaDominicaDominican RepublicGrenadaGuadeloupeHaitiJamaicaMartinique(Montserrat)Netherlands AntillesPuerto Rico [Mona Is]St. Kits and NevisSt. Lucia(St Pierre & Miquelon)St. Vincent & GrenadinesTrinidad and TobagoUS Virgin IslandsInsular Caribbean

Area

Total(000's

of km2)

0.4410.010.430.050.150.26

109.820.7548.380.341.69

27.5610.831.060.100.808.860.360.61n.a.0.395.130.34

228.36

Population

TotalPop.1995

millions

0.10.30.30.10.00.011.00.17.80.10.47.22.40.40.00.23.7

0.040.10.00.11.30.1

35.8

Pop.Density

1995#/km2

150.027.6609.31260.0126.7126.9100.594.7161.7270.6253.3260.5225.9357.5110.0248.8414.7136.1232.8n.a.

287.2254.6308.8156.7

Annualrate ofchange1990-95

(%)

0.61.50.40.72.93.50.8-0.11.90.31.82.00.71.0

-0.30.90.8-0.31.40.70.91.10.61.3

RuralPop.1995(%)

63.613.452.70.036.80.024.038.035.438.00.568.446.36.681.830.726.655.152.116.752.728.254.337.5

G N P per capita

Total1995(US$)

a11,9406,560

bn.a.bc

2,9901,4602,980

a250*1,510

bn.a.ba

5,1703,370n.a.

2,2803,730

b3,086

Realannualgrowth

rate1985-95

(%)2.4-0.8-0.8n.a.n.a.n.a.n.a.4.12.14.1n.a.-5.23.6n.a.n.a.n.a.1.84.83.9n.a.3.8-2.7n.a.0.9

Total]

(000'sofha)

91580040

1,84246

1,582480211753830

275115

n.a.111610

4,425

Forest (

%of land

area

20.515.80.00.0

26.70.016.861.332.711.847.30.816.235.830.00.031.030.68.2n.a.28.231.40.019.4

1995)

ha/cap

0.10.60.00.00.20.00.20.60.2n.s.0.2n.s.0.10.10.30.00.10.3n.s.n.a.0.10.10.00.1

Change in Forest Cover 1990-95

Naturalforests1995(000'sof ha)

91580040

1,59746

1,57548013

1603830

272115

n.a.111480

4,134

Totalchange1990-95(000'sof ha)

0-2200-10

-1180

-1320-7-4-79-200

-120-1

n.a.0

-130

-391

Annualchange(000'sof ha)

0-40000

-240

-260-1-1-16n.s.00-200

n.a.0-30

-7.8

Annualrate ofchange

(%)

0.0-2.60.00.0-4.40.0-1.20.0

-1.160.0-1.7-3.4-7.2-1.00.00.0-0.90.0-3.6n.a.0.0-1.50.0-1.7

Notes and Codes. Country - island-countries and/or territories with West Indian iguana populations; () indicates countries with a total population below 100,000 (expressed as 0.0 in corresponding column). Area - given figure isequivalent to total land area, excluding inland water bodies. GNP per capita - data from World Bank Atlas method, subtotals based on available data: (a), estimated to be upper-middle-income, $3,036 to $9,385; (b) estimated to behigh income, $9,386 or more; (c), estimated to be lower-middle-income, $766 to $3,035; (*) figure for lower-income countries is $765 or less. Forest Cover - 'Total forest' is the sum of natural forest and plantations. Change in ForestCover - method for data collection based on deforestation model (adjustment function) developed for correlation of forest cover change over time, incorporating ancillary variables (population change and density, initial forest coverand ecoregion). All columns - numbers may not tally due to rounding; (n.a.) no available data; (n.s.) no significant change or data indicating a very small value.

Sources of data. Socioeconomic indicators: World Development Report 1997. The State in a Changing World: Selected World Development Indicators, The World Bank, 1997; The World Bank Atlas 1995, The World Bank, 1996;World Population Prospects, United Nations, 1995; World Urbanization Prospects, United Nations, 1995; FAO Production Yearbook, 1996. Environmental indicators: State of the World's Forests 1997, FAO 1997; World DevelopmentReport 1997. The State in a Changing World: Selected World Development Indicators The World Bank, 1997; UN World Population Prospects, 1994; Proceed. XI World Forestry Congress, FAO 1997.

West Indian Iguana Habitat

By Robert Ehrig

West Indian xerophytic forests inhabited by iguanashave survived drastic climatic variation, geologicalactivity, and rising and falling sea levels throughouttheir existence. Although they are often less tolerantof unnatural disturbance than other vegetation com-munities, dry forests survive hurricanes and tropicalstorms and recover quickly if they are in good condi-tion. These xerophytic plant communities containsome of the world's hardest woods, harbor many spec-tacular bird species, and support the earth's largestsaurian herbivores.

Although the Lucayan, Caloosa, Taino, and ArawakIndians probably all utilized iguanas as food, it wasthe arrival of Europeans that precipitated dramaticdeclines in iguana populations and the destruction ofnative habitats. In modern times, West Indian dryforests have continued to suffer steady degradation.On larger islands and in populated areas, these forestsare mostly gone, although some excellent examplessurvive in remote or sparsely populated areas, primar-ily in Cuba and the Bahamas. Fragments in good con-dition still remain in a number of other areas, but mostare under intense pressure and in danger of being lostin the near future.

West Indian dry forests have been historicallyreferred to as thorn forests, due to the presence of cac-tus, agave, epiphytes, thorny or spiny trees and shrubs,and their typically low canopy. Stem densities arehigh, helping to reduce water loss. The substrate maybe sandy, but often consists of sharp, pitted limestonecontaining numerous holes and crevices. Solution andsink holes in which organic soils accumulate are com-mon, providing places for trees and shrubs to grow.Larger holes may be maintained in an open state bythe annual nesting activities of iguanas.

Good quality iguana habitat on Great Sand Cay,Turks and Caicos Islands.

The rough and inhospitable nature of West Indianiguana habitats, along with heat and rocky terrain,have made few people lament their destruction. Inmany areas, the absence of permanent fresh water hasbeen the most important factor preventing forestdegradation. On larger islands, the availability ofwater for irrigation has enabled agricultural develop-ment of forested areas. Limestone mining hasdestroyed large forest tracts on Cuba, Puerto Rico, andJamaica. In many countries, woodcutting for char-coal, an inexpensive cooking fuel, has decimated vastareas.

Goats, burros, sheep, cattle, and other free-rangingand feral mammalian browsers contribute to destruc-tion of iguana habitats by preventing natural regener-ation of vegetation. Non-native trees such asAustralian pine (Casuarina equisetifolia), non-nativenaturalized weeds such as jumbie bean (Leucaena leu-cocephala), and early successional natives such asAcacia macracantha have become dominant in manydegraded xeric forests. These species have very littlevalue for native wildlife. Lower plant diversity trans-lates into reduced food resources for wildlife, whichin turn leads to loss of more specialized organisms.

Conservation of West Indian iguanas will be diffi-cult in the face of growing, economically depressedhuman populations. Because the continued existenceof dry forest vegetation communities is imperative foriguana survival, protection of habitat should be thefirst priority of conservation efforts. Free-ranginglivestock and woodcutting for charcoal production areprobably the most common negative impacts on dryforest habitats in rural areas. Because xerophyticforests are slow growing and grazing by mammalianherbivores precludes regeneration, mammals must beremoved if vegetation is to recover. Reduction planswill need to involve compensation for livestock own-ers and may be facilitated by establishing a wardenfrom the local community. Fences may be required toexclude browsers kept for dairy purposes from iguanaareas. Elimination of woodcutting will undoubtedlyrequire a longer time frame. Several wardens will beneeded to enforce restrictions in larger areas.However, local employment opportunities could begenerated by establishing plant nurseries for nativespecies that include seed gathering and restorationplanting. Reforestation with native hardwoods suchas mahogany (Swietenia mahagoni) and black iron-wood (Krugiodendron ferreum) in clearly definedbuffer zones or close to settlements would be feasible,and plantings of a variety of indigenous species couldprovide firewood, medicinal plants, and wildlife habi-tat. Such programs could allow recovery of degradedhabitats and provide strong incentives for conserva-tion and wise management of forest resources.

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9

Overview of West Indian IguanaPopulations

As a group, West Indian iguanas are among the mostendangered lizards in the world, probably due in largepart to their exclusively insular distribution. As aresult of their low metabolic rates and naturally highpopulation densities, lizards in many mainland habi-tats are relatively resistant to extinction. However, therestricted ranges and small population sizes of lizardson islands render them highly susceptible to a varietyof human-caused threats. Pressure to exploit undis-turbed natural areas is particularly strong in the WestIndies, where unutilized land is often perceived aseconomically undesirable (Barzetti 1993).Recolonization following local extinction on islandsmay be quite rare because West Indian iguanas, likemost other terrestrial reptiles, are probably poor over-water dispersers.

According to IUCN Red List Categories (IUCN1994), four West Indian iguanids are consideredVulnerable, five Endangered, and eight CriticallyEndangered. Two taxa, the Turks and Caicos iguana(C. carinata carinata) and the Cuban iguana (C. nubi-la nubila), are still fairly numerous in the wild.However, both have been nearly extirpated on thelarger, more populous islands within their ranges, andtoday are restricted primarily to smaller, uninhabitedislets or cays. Although both still exist over a widearea, they are subject to a variety of human distur-bances, with the Turks and Caicos iguana reduced to10% of its former range. The rhinoceros iguana (C.cornuta cornuta) and the Andros Island iguana (C.cychlura cychlura), both ranked as Vulnerable, inhab-it increasingly fragmented ranges and are threatenedby invasive exotic species. Although it still occurs onmany islands, the Lesser Antillean iguana (I. deli-catissima) is undergoing very rapid decline as a resultof habitat loss, competition with introduced goats,predation by exotics, and hybridization with commoniguanas (I. iguana).

Of the West Indian iguanas ranked as Endangered,the majority occur in the Bahamas (the Exuma Islandiguana, C. cychlura figginsi; the Allen's Cay iguana,C. cychlura inornata; the San Salvador iguana, C.rileyi rileyi; and the Acklins iguana, C. rileyinuchalis). All of these taxa are restricted to a limitednumber of small islands or cays, often no more than afew hectares in area. While populations are generallystable, many of these islands are heavily visited bytourists and some taxa have been subject to illegalsmuggling in recent years. The Mona Island iguana(C. cornuta stejnegeri) occurs only on the remoteisland of Mona, where it is scarce due to predation by

feral pigs and cats, browsing by feral goats, anddestruction of nest sites.

While very small, the single population ofBartsch's iguana (C. carinata bartschi) in theBahamas appears to be healthy and stable, supportingall age classes. However, this subspecies is restrictedto one tiny cay with a high point of 6.2m and most ofits area below 3m. Because environmental catastro-phe, particularly in the form of a heavy hurricane, is avery real threat, this species has been ranked asCritically Endangered. Another Bahamian form, theWhite Cay iguana (C. rileyi cristata), has only onesmall population remaining from which illegal smug-gling has been confirmed. The Jamaican iguana (C.collei), the Lesser Caymans iguana (C. nubila cayma-nensis), the Grand Cayman iguana (C. nubila lewisi),the Anegada Island iguana (C. pinguis), and Ricord'siguana (C. ricordi), are probably currently far belownatural carrying capacity on the islands where they

Active iguana nesting site in the Hellshire Hills,Jamaica.

occur. The Jamaican iguana was believed extinct untilthe 1990 rediscovery of a tiny remnant population inthe remote Hellshire Hills. Since that time, a highlysuccessful captive rearing program involving over 100juveniles has helped provide a hedge against extinc-tion, but the wild population is still very much in peril.For the Lesser Caymans iguana, the only remainingviable subpopulation is that on Little Cayman, and itis subject to a variety of threats, particularly habitatloss and introduced predators. Based on recent genet-ic data, the Grand Cayman iguana has probably exist-ed at an extremely small population size for an evenlonger period than the Jamaican iguana. Genetic vari-ation among the remaining individuals examined thusfar appears to be very low, posing serious concernsregarding conservation efforts for this taxon. TheAnegada Island iguana has undergone precipitous

10

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lenn Gerber

declines in recent years, primarily due to competition Remains of a charcoal kiln in the Hellshire Hills,with feral livestock for food and predation by feral Jamaica.cats. The population of Ricord's iguana, historicallysmall and disjunct, is declining as a result of habitatdegradation and introduced species.

Table 2. Current Status of West Indian iguana populations according to the 1996 IUCN Red List. SeeAppendix 1 for explanation of listing criteria.

Taxon

Turks and Caicos iguanafBartsch's iguanaJamaican iguanaRhinoceros iguanaMona Island iguanaAndros Island iguanaExuma Island iguanaAllen's Cay iguanaCuban iguanaLesser Caymans iguanaGrand Cayman iguanaAnegada Island iguana

Ricord's iguana

San Salvador iguanaWhite Cay iguanaAcklins iguanaLesser Antillean iguana

EstimatedPopulation

30,000200-300

10010,000-17,000

1,500-2,0002,500-5,0001,000-1,200

400-50040,000-60,000

1,000100-175

200

2,000-4,000

500-1,000150-200

13,00015,000

Vulnerable

•

•

•

•

Endangered

•

••

•

•

CriticallyEndangered

•••

•••

•

•

ListingCriteria

Bl+2a,b,c,d,eBl+2b,c,e;C2b

Bl;2cAla,c,d,e

Alc,d,e+2c,eAla,c,e; Bl+2b; Cl

ClBl+2c

Ala,c,d,e+2c,eBl+2a,b,c,d,e

Bl+2b,c,e; C2bAla,b,c,d,e; Bl

+2a,b,c,e; Cl+2bAlc,e+2c,d,e;

Bl+2c,eC2

Bl+2e; C2Bl+2c; C2

Ala,c,d,e+2c,d,e;Bl+2a,b,c,d,e

† Although the population estimate for this taxon is relatively large, its range has contracted significantly inrecent years.

11

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lenn Gerber

Overview of Current Threats

The major threat to survival of West Indian iguanapopulations is habitat loss, a problem affecting virtu-ally all taxa. This process takes a variety of forms,including conversion of dry forests for mining(Dominican Republic, Jamaica), agriculture(Dominican Republic, Grand Cayman, LesserAntilles), charcoal production (Dominican Republic,Jamaica), timber extraction (Dominican Republic,Lesser Antilles), tourist resorts, housing develop-ments, and other real estate ventures (Bahamas, Turksand Caicos, Cayman Islands, Cuba).

An inevitable consequence of this disturbance is thearrival of human-commensal species which can act asunnatural predators or competitors for native species.While feral cats and mongooses primarily threatenjuvenile iguanas, dogs are capable of preying onadults. For some taxa, particularly the Jamaican,Lesser Caymans, and Anegada Island iguanas, preda-tion by introduced species appears severe enough thatpopulation recruitment is very low, with few juvenilespresent in the wild. Among smaller species of igua-nas, predation by introduced rats on juveniles andferal cats on all age classes can similarly lead todepressed population growth. Egg predation by feralpigs is a significant problem on Mona, Andros, partsof Cuba, and possibly Jamaica. Because they tramplenesting sites and decimate the native vegetation onwhich iguanas depend, feral livestock also pose a seri-

ous threat, particularly on Anegada, Mona, BoobyCay in the Bahamas, in parts of the Turks and Caicosand the Dominican Republic, and throughout theLesser Antilles. On some of these islands, over-browsing has stunted vegetation and produced radicalchanges in species composition.

Hunting is also a threat for several taxa, althoughthe reasons for this exploitation are varied. In Haiti,the Dominican Republic, and the Lesser Antilles,iguanas are hunted primarily for food, whereas in theBahamas and the Turks and Caicos, illegal poachingfor international trade is becoming an increasing con-cern. Finally, on islands undergoing very rapid urban-ization, particularly the Caymans and some of theLesser Antilles, road casualties are a significant causeof death for both adults and juveniles.

Overview of ExistingConservation Measures

All species of West Indian iguanas are protected inter-nationally under the Convention on InternationalTrade in Endangered Species (All rock iguanas onCITES Appendix I; the Lesser Antillean iguana onCITES Appendix II). Although many species alsoreceive some degree of national legislative protectionin the countries where they occur, local enforcementof regulations is sporadic. Protected habitat, in the

Table 3. Current Threats to West Indian iguana populations.

Taxon

Turks and Caicos iguanaBartsch's iguanaJamaican iguanaRhinoceros iguanaMona Island iguanaAndros Island iguanaExuma Island iguanaAllen's Cay iguanaCuban iguanaLesser Caymans iguanaGrand Cayman iguanaAnegada Island iguanaRicord's iguanaSan Salvador iguanaWhite Cay iguanaAcklins iguanaLesser Antillean iguana

HabitatLoss

•••••

••••••••••

Hunting/Trade

•

•

•••

•

•••

Dogs

•

••

••

••••••

•

Predation by FeralCats Mongooses

•

• •• ••

••••• ••

• •

AnimalsPigs

••••

•

Rats

•

•

••

IntroducedBrowsers

••

•

••

•

RoadCasualties

•

••

•

12

Natural area supporting iguanas on the east end of Grand Cayman.

Table 4. Existing conservation measures for West Indian iguanas.

Taxon


ProtectedAreas

•

••

•

••

•

•

NationalLegislation

•

••••••••••••••••

ExoticsControl

•

••

•

•

••

Research

•

•

•

••••••

••••

Education

•

•

••

•

•

SatellitePopulations

•

•

HabitatEnhancement

•

•

CaptiveBreeding

••

•

•

•

•

13

©R

ichard Hudson

form of national parks, nature reserves, or sanctuaries,exists for approximately half of all West Indian igua-nas. However, in many cases, these areas are verysmall (e.g., Cayman Islands) or represent only a tinyfraction of the species' total range (e.g., LesserAntilles). Even in countries with fairly extensivereserve systems (Turks and Caicos Islands, Cuba,Dominican Republic), limited resources for protectedarea maintenance remain a concern.

While at least some form of exotics control isunderway for six taxa of West Indian iguanas, thesepilot programs are aimed at single species on one ortwo islands (feral cats on Pine and Water Cays, Turksand Caicos; goats on Booby Cay, Bahamas; sheep onGuana Island, British Virgin Islands; mongooses inthe Hellshire Hills, Jamaica; feral cats on MonaIsland, Puerto Rico; rats on Low and White Cays,Bahamas). Although complete eradication is the goalfor feral cats and rats, other species such as mongoos-es will require continuous trapping to keep populationnumbers low in core iguana habitat. Fencing has suc-cessfully excluded feral goats and pigs from iguananest sites, particularly on Mona Island. Because ofthe variety of threats posed by exotic mammals tomost species of West Indian iguanas, control pro-grams will need to be expanded in the future, andimplemented on islands where they do not yet exist.

Field research is making a significant contributionto the conservation of many species of West Indianiguanas. Studies ranging from population surveys toecological and systematic investigations are takingplace which should provide the scientific data neces-sary to begin to develop species conservation plans formany taxa. For others, particularly Bartsch's iguanaand the Andros island iguana, such studies are stillurgently needed as little is known of their biology.

The only West Indian iguanas for which full-scalepublic education programs currently exist are the

Turks and Caicos and Grand Cayman iguanas. Eachyear, the National Trust for the Cayman Islands holdsa fair at which several thousand children have theopportunity to learn about iguanas and their habitatrequirements. The National Trust for the Turks andCaicos Islands has produced an iguana poster and reg-ularly provides information about iguanas to localschools. The Jamaican iguana conservation programinvolves education of local forest habitat users, partic-ularly charcoal burners and pig hunters. In theBahamas, signs informing tourists of the protectedstatus and vulnerability of iguanas have been helpful,particularly on small cays visited by private yachts.The IUCN/SSC West Indian Iguana Specialist Grouprecently sponsored production of a color poster urgingprotection of West Indian iguanas for distribution in asmany range countries as possible.

Secondary populations have been established forthree taxa, the Allen's Cay iguana, the Anegada igua-na, and the Acklins iguana. These satellite popula-tions have the potential to serve as reservoirs shouldprimary populations become extinct in the future.Similar programs are planned for the Jamaican igua-na, the Exuma Island iguana, and the White Cay igua-na, but have yet to be implemented.

Habitat enhancement, although it has the potentialto contribute to conservation efforts for all species ofWest Indian iguanas, has to date only been carried outfor two taxa. Clearing of patches of exotic forest hasprovided new nesting area on Mona Island, andremoval of exotic vegetation to prepare a release sitefor headstarted hatchlings is taking place on GrandCayman.

Captive breeding programs currently exist for sixtaxa of West Indian iguanas. In situ programs, such asthose on Jamaican and Grand Cayman, are havingimmediate effects on population viability through thesuccessful repatriation of headstarted juveniles.

14

Chapter 2. Taxonomic Accounts

Turks and Caicos iguanaCyclura carinata carinata

By Glenn Gerber and John Iverson

DescriptionThe Turks and Caicos iguana is a small (up to 770mmtotal length) rock iguana, characterized by a lack ofenlarged scales on the upper surface of the head, ros-tral scale in contact with the nasal scales, 80 to 110dorsal crest scales, enlarged, spiny whorls of scales onthe tail, and 9 to 10 dark vertical stripes on the dorso-lateral wall that fade with age (Schwartz and Carey1977; Iverson 1979). Body color varies among islandpopulations, from gray or brown to dull green. Insome populations, the head and neck have a vermicu-lated pattern, and the dorsal crest scales and the tail ofadult males are pale blue and reddish-brown, respec-tively. Body size is sexually dimorphic and variesamong islands, with the smallest animals occurring onLong Cay on the Turks Bank, where adult males andfemales average 221mm snout-vent length (SVL)(0.40kg) and 185mm SVL (0.24kg), respectively.Iguanas are largest on Plandon Cay on the east side ofthe Caicos Bank, where adult males and females aver-age 325mm SVL (1.41kg) and 268mm SVL (0.64kg),respectively (G. Gerber and M. Welch, unpublisheddata). The largest recorded male and female are fromPine Cay on the west side of the Caicos Bank, mea-suring 360mm SVL (1.86kg) and 290mm SVL(1.14kg), respectively.

DistributionThis subspecies is native to the Turks and CaicosIslands, located southeast of the Bahamas and approx-imately 150km north of Hispaniola. The islands lie ontwo shallow oceanic banks, the Turks Bank and theCaicos Bank, separated by a deep water channel.Although politically separate from the Bahamas, theTurks and Caicos are geologically part of the BahamaArchipelago. There are 10 islands in the Turks Bankand over 100 islands in the Caicos Bank, with a com-bined surface area of approximately 500km2.Maximum elevation is about 85m and the climate andvegetation are similar to that of the Bahamas.Historically, this subspecies occurred throughout theTurks and Caicos, but has been extirpated from manyareas, including most of the larger islands.

Status of populations in the wildA comprehensive survey of iguana populations in the

Turks and Caicos was conducted in 1995 (G. Gerberand M. Welch, unpublished data; Fig. 1). Based onpreliminary analyses, about 30,000 adults remain inthe wild. Iguanas were found on 56 of 120 cays visit-ed. However, most cays with iguanas are very small(area f 1 ha) and the combined area of all cays withiguanas is only about 28km2. Over half of the areaoccupied by iguanas consists of five cays (Salt, JoeGrant's, Major Hill, Dellis, and Pine) where iguanasare extremely rare (Fig. 1), probably due to the pres-ence of introduced mammals (Fig. 2; see also Iverson,1978, and Smith, 1992). The combined area of cayswhere iguanas are still common (densities can exceed30 adults per ha; Iverson, 1979) is only 13km2, mostof which is accounted for by three cays (BigAmbergris, Little Ambergris, and East Bay), thelargest of which (Big Ambergris, 4.3km2) is privatelyowned and under development. A comparison of the1995 survey with a less extensive survey conducted inthe mid-1970s (Iverson, 1978) suggests that at least 13iguana populations, most on relatively large islands,have been extirpated over the last 20 years.

Ecology and natural historyIverson (1979) studied the natural history of this sub-species in the Caicos Islands from 1973 to 1976. Thisiguana is most abundant in rocky coppice and sandystrand vegetation habitats, and sandy habitat isrequired for nesting. The Turks and Caicos iguana isdiurnal and spends the night in burrows it has dug orin natural retreats in or under rocks. It is primarilyherbivorous throughout its life, feeding arboreally orterrestrially on the fruits, flowers, and leaves of atleast 58 plant species, as well as occasional insects,mollusks, crustaceans, arachnids, lizards, and carrion(see also Auffenberg, 1982). In captivity, it readilytakes both animal and plant food.

Adult males are territorial throughout the year,apparently to guarantee access to food and females.Courtship and mating occur in May, with a singleannual clutch of two to nine eggs laid in June.Females defend the nest burrow for several days toseveral weeks after nesting, but are not territorial dur-ing the rest of the year. Hatching occurs inSeptember, after about 90 days incubation, and hatch-lings average 80mm SVL and 14.6g.

Growth rates in juveniles average slightly less than20mm per year until maturity, which in males occursat about 7 years (220mm SVL, 0.33-0.48kg), and infemales at 6 to 7 years (185-200mm SVL, 0.20-0.30kg). Adults grow much more slowly (0.2 to

15

1.7cm/yr) and show strong sexual dimorphism.Annual survivorship ranges from about 55% for the

first three years of life, to about 67% during years fourthrough six, to 90-95% in adults. Life table analysissuggests that mean cohort generation time is 14 years.Preliminary data suggest that some individuals live atleast 20 years.

HabitatThe current human population of the Turks andCaicos is about 8,000, inhabiting eight of the largerislands (Fig. 1). On these islands, considerable habi-tat has been lost to human activities, particularlytourist-related, and the rate of development is increas-ing. An even more significant cause of habitatdestruction has been the mammalian predators andlivestock accompanying modern settlement (Fig. 2).Iguanas are still common only on uninhabited islandsthat have no introduced mammals. However, manyuninhabited islands exist which could support densepopulations of iguanas if rid of feral mammals.

ThreatsThe primary threat to Turks and Caicos iguanas isintroduced mammals, particularly cats and dogs.Iverson (1978, 1979) documented the near-extirpationof a population of over 5,000 adult iguanas from PineCay (3.9km2) in just three years as a result of preda-tion by feral cats and dogs. Feral livestock (goats,cows, donkeys, and horses) pose a serious threat also,presumably because they compete for food plants,alter the vegetational composition of habitats, andtrample soft substrates where iguanas burrow andnest. In 1995, iguanas were found on only five of 26islands with cats or livestock (G. Gerber and M.Welch, unpublished data). Furthermore, iguanas onthese five islands were rare, whereas iguanas onislands without introduced mammals were common.Iguanas are still occasionally eaten by local fisher-men, and although illegal exportation for internation-al trade is undocumented, it probably occurs.

Current conservation programsThe Turks and Caicos has a fairly extensive system ofnational parks, nature reserves, and sanctuaries, anumber of which encompass areas supporting iguanas(Fig. 1). Unfortunately, reserves are not immune tothe effects of introduced mammals (Fig. 2), and fewgovernmental resources are presently allocated tomaintain or enforce protection of non-marine parks.However, with the establishment of the National Trustfor the Turks and Caicos Islands in 1994, a significantincrease in conservation of terrestrial wildlife andhabitats has begun. Largely due to the urging of theNational Trust, legislation to protect iguanas within

the Turks and Caicos Islands has recently been draft-ed. In addition, the government has granted theNational Trust stewardship of Little Water Cay, whichsupports a large population of iguanas but needs man-agement due to its popularity with tourists and thethreat of invasion by feral cats over a recently formedisthmus to Water Cay. A similar transfer is currentlypending for Little Ambergris and East Bay Cays. TheNational Trust recently initiated a trapping program toremove feral cats from Pine, Water, and (if needed)Little Water Cays. If successful, this program willremove the threat of cats from Little Water Cay andallow iguanas to repopulate Pine and Water Cays. OnLittle Water Cay, boardwalks and observation towershave been constructed at two popular landing sites toreduce the negative impacts of tourism, and a visita-tion fee has been instituted with the proceeds support-ing conservation activities. In addition, the NationalTrust has initiated a public education program thatincludes distribution of an informative poster aboutiguanas and a tour of all schools to discuss iguanasand other conservation issues.

A preliminary study of genetic variation in theTurks and Caicos iguana using blood samples collect-ed from 29 island populations in 1995 found signifi-cant differences among islands and revealed a patternof strong regional differentiation (M. Welch, unpub-lished data). This preliminary study utilizedmicrosatellite markers developed for C. nubila, ofwhich only two were informative; further descriptionof inter-island genetic variation awaits the develop-ment of markers specific to C. carinata. No captiveprograms currently exist for this taxon.

Critical conservation initiatives• Legislation prohibiting the introduction ofmammals to uninhabited islands in the Turks andCaicos.• Incorporation of all uninhabited islands sup-porting iguanas into the current reserve system.• Increased governmental commitment to terres-trial conservation, including the provision ofresources necessary to enforce compliance withenvironmental regulations.

Priority projects1) Eradicate or control introduced mammals onislands uninhabited by humans. Free-ranging domes-tic livestock should also be captured and relocated toinhabited islands.

2) Complete study of genetic differentiation amongisland populations.

3) Establish a long-term monitoring program and

16

Fig. 1. Map of the Turks and Caicos Islands showing ocean banks (gray surrounded by dotted lines), terrestri-al reserves (lighter shading around islands), and abundance of iguanas on islands in 1995 (white = not found,hatched = rare, black = common to abundant). Iguanas were found on 24 of 31 cays visited in Chalk Sound.Names of islands inhabited by humans are underlined.

Fig. 2. Map of the Turks and Caicos Islands showing where feral or free-ranging domestic mammals were(black) and were not (white) found in 1995. Labels indicate the types of mammals identified by sight, tracks,or droppings. The label "visited by dogs" indicates islands frequented by dogs residing on nearby islands.Other features labelled as in Fig. 1.

17

Geographical Information Systems database of iguanapopulations.

4) Conduct field studies to determine the conditionsnecessary to re-establish healthy, self-sustaining pop-ulations of the Turks and Caicos iguana on islandsuninhabited by humans, supporting suitable habitat,and lacking feral mammals. Results could serve as avaluable model for other West Indian rock iguanas,some which may depend on reintroduction programsfor their survival.

Contact personsGlenn Gerber and Mark WelchDepartment of Ecology and Evolutionary BiologyUniversity of TennesseeKnoxville, TN 37996 USATel: (423) 974-3065Fax: (423) 974-3067E-mail: [email protected]

[email protected]

John IversonDepartment of BiologyEarlham CollegeRichmond, IN 47374 USATel: (317)983-1405Fax: (317)983-1497E-mail: [email protected]

Ethlyn Gibbs-WilliamsTurks and Caicos National TrustButterfield SquareProvidencialesTurks and Caicos IslandsTel/Fax: (649)941-5710E-mail: [email protected]

Bartsch's iguanaCyclura carinata bartschi

By Sandra Buckner and David Blair

DescriptionBartsch's iguana is greenish to brownish-gray, with ayellow dorsal crest, faint yellow-brown reticulationson the bodies of the adults, and a golden iris(Auffenberg 1976). Large specimens are approxi-mately 770mm total length. Schwartz and Carey(1977), who examined nine specimens (seven in life),recorded an SVL of 335mm in the largest male and285mm in the largest female. They state, "in generaltheir body colors seem to be somewhat paler (tending

towards creams to pale grays) than those of nominatecarinata (gray to dull tan)." As this subspecies has notbeen studied in the field, the paler body color may beaccounted for by temperature or time of year whenspecimens were observed.

DistributionThis subspecies is restricted to Booby Cay, located0.5km off the eastern end of the island of Mayaguanain the southern Bahamas. The cay is 2km in length,approximately 750m wide at its northeastern end, nar-rowing to less than 100m, and again widening toapproximately 250m at its southwestern end.Approximately 30% of the cay is taken up by twoponds. Iguanas probably originally ranged over theentire cay but were likely concentrated on the easternhalf where the vegetation was more dense. There arehistorical anecdotal references to the presence of igua-nas on Mayaguana. However, there have been norecent sightings on the island, which has an area of285km2 and a human population of approximately 500concentrated on the western half. There are no roadsextending to the eastern end of the island and it is con-ceivable that iguanas still exist in this area.

Status of population in the wildSurveys indicate that iguanas were fairly numerous in1988 and 1997 with all age classes present, indicatinga healthy reproducing population. However, this sub-species is restricted to one population on a singlesmall cay with a high point of 6.2m and most of itsarea below 3m. Although no census has been con-ducted, it is unlikely that the population exceeds 500animals, and is estimated to be between 200 and 300(Blair 1991a; Bendon 1997).

Ecology and natural historyNo research has been conducted on this subspecies.Like the Turks and Caicos iguana, this subspecies isprimarily herbivorous throughout life, althoughinsects, mollusks, crustaceans, arachnids, lizards, andcarrion are occasionally consumed. Burrows orcrevices in or under rocks are used for retreat.

HabitatLike the Turks and Caicos iguana, Bartsch's iguanaprobably inhabits rocky coppice and sandy strand veg-etation habitats (Iverson 1979). D. Blair reported thathe saw one group of about ten goats on the easternportion of the island in 1988. The vegetation washeavily grazed and stunted, and the area was litteredwith goat droppings. J. Bendon reported the presenceof goats in 1997, but indicated that they did not appearto be impacting the habitat severely.

18

ThreatsThe immediate threat to the single population ofBartsch's iguana is the presence of goats, introducedto Booby Cay by the individual who holds the landunder Crown lease. The cay is not readily accessiblefrom the settlements on Mayaguana which could bethe reason this population has survived so far.However, the cay is visited on an irregular basis bylocal conch fisherman, who sometimes overnightthere. Catastrophe, particularly in the form of a hurri-cane or hurricane surge, is a very real threat.

Current conservation programsAll Bahamian rock iguanas are protected under theWild Animals Protection Act of 1968. There havebeen no reports of poaching of iguanas on Booby Cayand it is not known if any are taken by local fishermenfor consumption. The Bahamas National Trust hasproposed to the Bahamas Government that BoobyCay, which is also of significant value for nestingseabirds, be named a protected area under the nation-al parks system.

Representatives of the Wildlife Committee of theBahamas National Trust and the Department ofAgriculture began to survey the status of the iguanason Booby Cay in early 1995 and to initiate removal offeral goats. There are no other research programs inprogress or currently proposed for this subspecies,and no captive programs currently exist.

Critical conservation initiatives• Removal of feral goats from Booby Cay. Priorto such action, the status of the Crown Lease willneed to be reviewed and ownership of goatsdetermined.• Establishment of protected area status forBooby Cay.• Institutional strengthening of responsible agen-cies to develop enforcement capabilities.• Initiation of a national education program fortourists and residents.

Priority projects1) Assess the present status of the population onBooby Cay, identify plant species cay wide, andmonitor vegetation changes after removal of goats.

2) Determine whether any subpopulations exist at theeastern end of Mayaguana and establish captivebreeding programs with the potential goal of restock-ing on Mayaguana.

Contact personsSandra BucknerBahamas National TrustPO Box N4105Nassau, The BahamasTel: (242) 393-3821Fax: (242) 393-3822E-mail: [email protected]

David BlairCyclura Research CenterPMB #510, 970 West Valley Parkway,Escondido, CA 92025 USATel: (760) 746-5422Fax: (760) 746-1732E-mail: [email protected]

Jamaican iguanaCyclura collei

By Peter Vogel

DescriptionThe Jamaican iguana is a moderate-sized rock iguana,with SVL reaching 428mm in males and 378mm infemales. Schwartz and Henderson (1991) describecoloration as green, grading into slaty blue withoblique lines of dark olive-green on the shoulder.Three broad triangular patches extend from dorsalcrest scales to venter, with dark olive-brown zigzagspots. The dorsal crest scales are somewhat brighterbluish-green than the body. The top of the head iswashed green and the dorsal and lateral body surfacesare blotched with straw, with the blotches breaking upinto small groups of spots. Wild individuals, particu-larly nesting females, often appear deep reddish-brown in color after digging in the coarse ferralic soilsof the Hellshire Hills region.

DistributionAccording to Sloane (1725) who visited the island in1688, iguanas were once common in Jamaicaalthough their distribution seems to have been restrict-ed to the drier sections of the south coast, at least inhistoric times. The Jamaican iguana declined dramat-ically during the second half of the 19th century,probably due to the introduction of the Indian mon-goose (Herpestes javanicus [=auropunctatus]),changing land use patterns, and human populationgrowth. Today, the iguana survives only in theHellshire Hills, a rugged limestone area of 114km2

with fringing wetlands and beaches located 20kmwest of Kingston. Despite their closeness to

19

Jamaica's densely populated capital, the HellshireHills persist as a wilderness area because of theirruggedness and lack of surface water, making themunsuitable for agriculture and large-scale settlement.

Status of population in the wildAt the beginning of the century, the Jamaican iguanawas thought to have survived only on the GoatIslands, two small islets off the Hellshire Hills. Thespecies was believed extinct after this population dis-appeared in the 1940s. However, the continued sur-vival of the Jamaican iguana in the Hellshire Hills wasconfirmed in 1970, and again in 1990. A preliminarysurvey in 1990 revealed a small surviving populationof perhaps a hundred or so animals in the least dis-turbed central and western sections of the HellshireHills, and two active nesting sites. Iguanas have dis-appeared from northern and eastern sections of theHellshire Hills because of extensive charcoal produc-tion, use of dogs for pig hunting, and human settle-ments. There may be no more than a hundred adultsremaining in the wild, and juvenile recruitmentappears to be minimal.

Ecology and natural historyRugged limestone outcroppings make up much of theHellshire Hills, although coarse red ferralic soil hasaccumulated in crevices and depressions. Soil suit-able for nesting is comparatively rare. The vegetationof the Hellshire Hills consists of varying formationsof tropical dry forest. The area supports about 300species of higher plants, including 53 endemics.Jamaican iguanas are found only in the remotest sec-tions of the Hellshire Hills where the forest remains ingood condition. Jamaican iguanas feed on leaves,fruits, and flowers of a wide variety of plant species,supplemented occasionally by animal matter, includ-ing snails. Diet composition changes seasonallyaccording to the flowering and fruiting cycles of localplant species.

Following the rediscovery of the Jamaican iguanain 1990, the two known communal nest sites havebeen observed intensively (Vogel 1994). Nestingoccurs in underground tunnel systems of nest burrowsfilled with loose soil. Gravid female iguanas begindigging trial holes long before egg laying. Femalesdeposit their eggs in mid-June, and hatchlings emergeapproximately 85-87 days later. After oviposition,nest guarding by females lasts up to two weeks, andinvolves aggressive interactions, including threat dis-plays, biting, and chasing. Clutch size averages 17eggs (range 16-20). Hatching success varies from 0 to100% and appears to be related to maternal body size.

HabitatThe northeastern portion of the Hellshire Hills hasbeen totally degraded, and much of the land in thissection is now virtually barren. Along the north-cen-tral border, the charcoal burners have moved 2-3kminto the forest, and are approximately 1.5km from thetwo known nesting sites. Along the south coast, char-coal burners have cut some of the coastal forest,although they have not yet expanded their activitiesnorthwards into the limestone karstland. The centraland most of the western sections of the Hellshire Hillsare still covered with little disturbed, primary tropicalforest. However, even in intact forest, iguanas arevulnerable to pressure from exotic predators, especial-ly dogs. In moderately exploited sections of the for-est, many trees survive, and there is a rapid regrowthof shrubs and small trees. Such areas might still pro-vide habitat for the iguanas if pressure from exoticpredators could be controlled (Vogel et al. 1995).

The most promising site for the establishment of anew subpopulation in the wild appears to be GreatGoat Island, where a population of iguanas had sur-vived until at least the late 1940s. However, thenumerous goats on the island would have to beremoved, and the ground vegetation given an opportu-nity to recover before any release could take place. Atthe same time, the island could be rendered mongoosefree. The removal of goats would have to be careful-ly negotiated with the goat owners who live in a near-by fishing village. Other potential release sitesinclude Little Goat Island and the Portland Ridge area,which like the Hellshire Hills retains extensive areasof relatively undisturbed dry forest.

ThreatsOne of the most significant pressures on the remain-ing population in areas of intact forest is exotic preda-tors, including mongooses, cats, stray dogs, and pos-sibly feral pigs. Mongooses are very commonthroughout the Hellshire Hills and several observa-tions suggest that they at least occasionally prey oniguana eggs. During the nesting season, they showvivid interest in iguana trial diggings. Mongoosesprobably prey heavily on hatchlings and young juve-niles as well, but few data exist. Cats, which also preyon juveniles, have been observed at various locationsin the Hellshire Hills, including nesting areas. Thedogs used to hunt feral pigs are of particular concern,as they are able to take even adult iguanas (Woodley1980). Although feral pigs have not been observeddisturbing iguana nests in the Hellshire Hills, evi-dence from Mona Island suggests that they are poten-tially important egg predators (Wiewandt 1977).

Another significant problem is the burning of theforest for charcoal production, a local industry that

20

provides income to some 10,000 Jamaicans.Approximately a third of the Hellshire Hills is badlydegraded as a result of this enterprise. Short-termmanagement policies have involved establishing goodpersonal relationships with the burners and trying toconvince them to move east or west, away from igua-na populations and sensitive areas in the center of theHellshire Hills. Longer term solutions aim at estab-lishing specified buffer zones with low-scale, sustain-able charcoal production. Development projectsproposing large scale limestone mining and humansettlements also threaten the eastern half of theHellshire Hills. Although a few localized limestonequarries might have only limited impact on the igua-nas and their habitat, the new roads that would be con-structed to facilitate the mining process wouldundoubtedly allow charcoal burners, pig hunters, andother forest users to migrate further into the forest.

Current conservation programsAlthough most of Jamaica's remaining ecologicallyimportant forests, including the Hellshire Hills, areowned by the government and protected by law underthe Forestry Act of 1937, the act has received littleenforcement. Burning of wood to produce charcoal,slash and burn agriculture, and other destructive usesof the forest still progress. The Hellshire Hills is cur-rently under evaluation as a potential site for a newnational park (Jamaica Conservation andDevelopment Trust 1992). To provide interim protec-tion to the area until national park status can beachieved, the Natural Resources ConservationAuthority has been petitioned requesting that theHellshire Hills be declared a protected area under theNRCA Act of 1991. Designation of a protected areawould represent a promising legal instrument to pre-vent the expansion of large-scale development pro-jects in the Hellshire Hills.

Following the rediscovery of the species in 1990, alocal Jamaican Iguana Research and ConservationGroup comprising representatives from the Universityof the West Indies, the Natural ResourcesConservation Authority, Hope Zoological Gardens,and the Institute of Jamaica was formed. The groupcarried out an initial field survey during which 23sightings representing at least 15 different individualswere made (Vogel and Kerr, in press). In addition, anumber of signs were found including fecal pellets,tail impressions, and pieces of shed skin. Since then,the group has continuously monitored the two knownnesting sites and witnessed each nesting season(Vogel 1994). Each year, about eight females areknown to have deposited eggs. A detailed study of thenatural history of the species is currently being carriedout by Richard Nelson, a postgraduate student in the

Department of Zoology, University of the West Indies.His work includes a systematic assessment of theHellshire Hills habitat, as well as fieldwork on feedinghabits, home range use, migration patterns, and repro-ductive biology.

To devise a comprehensive plan for the recovery ofthe Jamaican iguana in the wild and to draw interna-tional attention to their conservation needs, an IUCN-sponsored workshop was held in Kingston in 1993(CBSG 1993). The goals of the workshop were to usecomputer modelling techniques to systematicallyevaluate the threats to iguana populations and howthey might be mitigated through various managementstrategies, and to heighten awareness about the impor-tance of conserving the biodiversity of the HellshireHills. After several computer simulations were rununder a variety of scenarios, it became clear that thecurrent level of mortality of juvenile iguanas in thewild was too high to permit survival of the population.This led to recommendations for a headstarting pro-gram, in which 50% of the young from wild nestswere brought into captivity for up to four years. Oncethese individuals have attained large enough body sizeto avoid mongoose predation, they will be acclimatedto natural foods and local conditions and released intomanaged areas within the Hellshire Hills. Initial pilotreleases in 1997-1999 have involved subadults out-fit-ted with radiotransmitters so that their movements pat-terns and survivorship rates can be carefully monitored.

A program to rear a group of approximately 100captive juveniles for headstarting is underway at HopeZoological Gardens in Kingston under the direction ofcurators Rhema Kerr and Nadin Thompson. In addi-tion to providing a safe environment for juveniles togrow, the zoo is sponsoring studies of juvenile nutri-tion, social interactions, thermoregulation, and dailyactivity patterns (Gibson, 1993). The zoo also hasplans to develop an exhibit on dry tropical forestecosystems which highlights the native plant and ani-mal species of the Hellshire Hills.

In 1994, an ex situ captive population was initiatedwith the importation of 12 individuals to three U.S.institutions (Indianapolis Zoo, Fort Worth Zoo,Gladys Porter Zoo). In 1996, this group was supple-mented by a second importation of 12 individuals tothe San Diego Zoo (Center for Reproduction ofEndangered Species), the Central Florida Zoo, and theSedgwick County Zoo. Genetic studies carried out byS. Davis have insured that the captive breeding nucle-us represents as many founders as possible, thus sam-pling a diverse cross-section of the wild gene pool.With successful propagation in the U.S., the programwill expand to other facilities. Once a target popula-tion of 200 is achieved, individuals will be returned toJamaica for headstarting to assist recruitment into the

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wild population. As a further safeguard against extinc-tion, captive-reared iguanas may also ultimately beused to establish satellite populations on the GoatIslands provided they can be rendered free of predators.

Critical conservation initiatives• Designation of the Hellshire Hills as a protect-ed area, and ultimately as a national park.• Prevention of further population declinethrough access restrictions, regular patrolling,removal of dogs, and protection of nest sites andhatching young.• Establishment of sustainable forest use pro-grams in specific buffer zones with low-scale,sustainable charcoal production• Exploration of other traditional non-invasiveuses of the forest, including collection of medic-inal plants, and fishing and crab hunting incoastal areas.

Priority projects1) Promote recovery of the iguana population throughpredator control.

2) Continue Hope Zoo headstarting program andtracking of released radiocollared individuals in theHellshire Hills.

3) Conduct field research, including habitat assess-ment, feeding ecology, home range use, migration pat-terns, reproduction, and survivorship.

4) Develop an education program in which schools arevisited and the importance of iguana conservation iscommunicated to local people. Programs could ini-tially be concentrated in the Hellshire Hills but shouldeventually include Kingston and surrounding commu-nities.

5) Establish an iguana sanctuary on Great Goat Islandfollowing mongoose eradication, removal of goats,and restoration of vegetation.

Note: A portion of the material presented in thisspecies account was adapted from a previously pub-lished work (Vogel et al. 1996).

Contact personsPeter VogelDepartment of Life SciencesUniversity of the West IndiesKingston 7, JamaicaTel: (876) 927-1202Fax: (876) 927-1640E-mail: vogel @uwimona.edu.jm

Richard NelsonNatural Resources Conservation Authority53 1/2 Molynes RoadKingston 10, JamaicaTel: (876) 923-5155 or 5125Fax: (876) 923-5070E-mail: [email protected]

Richard HudsonDepartment of HerpetologyFort Worth Zoo1989 Colonial ParkwayFort Worth, TX 76110 USATel: (871)817-7431Fax: (871)817-5637E-mail: [email protected]

Rhema Kerr and Nadin ThompsonHope Zoological GardensMinistry of AgricultureKingston 6, JamaicaTel/Fax: (876) 927-1085E-mail: [email protected]

[email protected]

Rhinoceros iguanaCyclura cornuta cornuta

By Jose Ottenwalder

DescriptionThe rhinoceros iguana attains a large adult size, withSVL up to 560mm in males and 510mm in females.Large males weigh between 6 and 10kg. Adults aregrayish brown, dark brown, dark gray, or even black,without pattern, and with the venter less heavily pig-mented than the dorsum. Bright colors are entirelyabsent. Juveniles are similar in appearance to adults,but with approximately nine paler crossbars whichdisappear relatively soon after hatching. Minimumrecorded SVL for juveniles is 80mm.

According to Schwartz and Carey (1977), rhinocer-os iguanas can be distinguished from the other tworecognized subspecies, the Mona Island iguana (C.cornuta stejnegeri) and the extinct Navassa Islandiguana (C. cornuta onchiopsis; Schwartz andHenderson 1991), by a combination of scale countsand femoral pore number. In the DominicanRepublic, the only West Indian country where two dis-tinct species of rock iguanas are found, the rhinocerosiguana and Ricord's iguana can be easily differentiat-ed. In contrast to the diagonally barred back and sidesof Ricord's iguana, rhinoceros iguanas are uniformly

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dark on their back and sides (Schwartz and Carey1977).

DistributionRhinoceros iguanas are still widely distributedthroughout Hispaniola, including most of its offshoreislands (Fig. 3). Their current geographic range isfragmented relative to their more continuous histori-cal distribution, and is strongly associated with xericregions of lower human population density.Islandwide, 20 or more subpopulations may exist,assuming that at least half of the Haitian populationsknown 20 years ago still survive (Ottenwalder andMeylan, unpublished manuscript). Most iguana con-centrations are found along the southern side ofHispaniola, with the highest numbers in south-south-western Dominican Republic.

In the Dominican Republic, a minimum of ten sub-populations, many of which contain further subdivid-ed populations, are known from the north-northwest(f2, Valle del Cibao Oriental, Llanura Costera delAtlantico north of Cordillera Septentrional), thenortheast (1, eastern end of Samana Peninsula), thesoutheast (g2, La Altagracia coastal region south ofthe line between Bayahibe-Boca de Yuma-Macao,including Isla Saona), and the south-southwest ( 5,from Bani Province west to the Neiba Valley andsouth to the Peninsula de Barahona, including IslaBeata). In Haiti, ten or fewer increasingly threatenedsubpopulations may still exist. Surveys conducted byP. Meylan in 1975 and information gathered by J.Ottenwalder and others during the 1980s indicatesthat rhinoceros iguana populations, while under heavyhunting and habitat pressure, were until recentlyknown from Tortue Island, Massif du Nord, Gonaivesregion, southeastern tip of Gonave Island, PetitGonave Island, Cul-de Sac Valley around Lake EtangSaumatre, and several areas of the Tiburon Peninsula,including Belle Anse, Marigot, Jacmel, Aquin, LesAnglais, Jeremie, Ile Grande Cayemite, Ile PetitCayemite, and other small offshore islands and caysbetween Coral and Petit Trou de Nippes (Ottenwalderand Meylan, unpublished manuscript).

Status of populations in the wildRhinoceros iguanas were common and widespreaduntil the early 1950s, but accurate information con-cerning current population estimates on Hispaniola islacking. Unpublished data based on opportunisticsurveys are available for a few localities, but are inad-equate for extrapolation to other areas facing differentlevels of disturbance, particularly in Haiti.Observations on population and habitat trends record-ed since the 1970s provide a fair but rough approxi-mation of 10,000 to f17,000. The highest densities

are found on the Barahona Peninsula, Isla Beata, andthe Valle de Neiba-Cul de Sac region. Moderate pop-ulations densities may still exist in localized, isolatedareas of the Bani-Azua region in the DominicanRepublic, and Petit Gonave Island, the Cayemiteisland-complex, and the Lake Etang Saumatre basin inHaiti.

Rhinoceros iguana densities are low in the majorityof the areas where they presently occur and appear tobe declining due to increasing human pressure and theimpact of feral mammals. Local extirpations areknown from both Dominican Republic and Haiti.Populations are seemingly stable only on Isla Beataand the extreme of the Barahona Peninsula insideParque Nacional Jaragua, although predation by intro-duced carnivores has been documented.

Ecology and natural historyRhinoceros iguanas are most abundant in, althoughnot restricted to, dry forests characterized by xeric,rocky habitats of eroded limestone in coastal terracesand lowlands of the mainland and several offshoreislands and small cays. In areas supporting iguanas,mean annual rainfall ranges from 470 to 1000mm, andmean annual temperature is 25°C. With some excep-tions, the species ranges in elevation from -35m (IslaCabritos, Lake Enriquillo) up to 400m. It is found ina variety of subtropical life zones and habitat types,including thorn scrub woodland, dry forest, and tran-sitional semideciduous to subtropical moist forests.

In addition to the habitat conditions described forareas of sympatry with Ricord's iguana, the variety ofplant communities occupied by the rhinoceros iguanaelsewhere in Hispaniola clearly indicates the ecologi-cal generalism and adaptability of this species. Whilemost areas now exhibit a xeric mosaic of habitats as aresult of human disturbance, variation in dry forestcomposition and structure of remaining undisturbedareas is generally influenced by edaphic and climaticfactors. Habitat profiles of areas supporting rhinocer-os iguanas are given below (vegetation data fromGarcia and Alba 1989; DVS/SEA 1990; Hager andZanoni 1993; DNP/AECI 1993; Mejía and García1993; Ottenwalder and Meylan, unpublished manu-script; J. Ottenwalder, unpublished data).

Disturbed dry forest. Characterized by decliningiguana populations, these areas exist in various stagesof succession and are impacted by charcoal produc-tion, livestock grazing, fires, hardwood extraction,and other activities. Prosopis juliflora forest, a wide-spread invasive community occupying areas of formernatural dry forest, represents one such habitat. This 6-8m forest is dominated by Prosopis juliflora-Acaciamacracantha association, with reduced presence of

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g

Bursera simaruba, Phyllostylon rhamnoid.es, Sennaatomaria, Lemaiocereus hystrix, Pilosocereus poly-gonus, Opuntia moniliformes, Neoabbottia panicula-ta, and Caesalpinia coriaria. A second type of dis-turbed dry forest is found in iguana localities aroundMontecristi in the northwest, at the southeastern endof Altagracia Province including areas in ParqueNacional del Este, and from Las Tablas and Galeon deBani to Llanura de Azua to Cabral, continuing into theNeiba Valley. The forest canopy is 5-6m, and is dom-inated by cacti. Trees include Prosopis juliflora,Pilocereus polygonus, Lemaireocereus hystrix,Opuntia moniliformes, Neoabbottia paniculata, andCapparis ferruginea. A very few Guaiacum offlci-nalis and G. sanctum are now left as a result of selec-tive logging. Shrubs include Cylindropuntia caribea,Harrisia nashii, Tournefortia stenophylla,Caesalpinia sp., Cordia globosa, Boerhavia scan-dens, Turnera diffusa, and Pictetia spinifolia. Withthe exception of C. caribea, most of these species areexpected to eventually disappear with continued habi-tat alteration.

Natural dry forest on slopes. This community occurson the north lake of Lake Enriquillo on foothills 100-400m in areas of stony soil with little organic materi-al. The vegetation is characterized by trees, 30% ofwhich are deciduous, approximately 30 species ofshrubs, half which are thorny, a few herbs, and prolif-ic vines. The 6-1 lm canopy includes Bursera simaru-ba, Guaiacum sanctum, Phyllostylon rhamnoides,Colubrina elliptica, Senna atomaria, Guaiacum offlc-inale, Exostema caribeum, Capparis flexuosa, and C.ferruginea.

Natural dry forest on rocky substrate. This low ele-vation, primarily cactus community occurs in the low-lands bordering the south Lake Enriquillo basin. Thesite is characterized by sandy soil and rocks on shore-lines, becoming more rocky on slopes with little finesoil. Rainfall is erratic (470-600mm), and vegetationconsists of a slow growing shrubby, open tree canopyup to 3-4m. Trees include Acacia scleroxylla,Cameraria linearis, Capparis ferruginea, Guapirabrevipetiolulata, Bursera simaruba, Plumeria subses-silis, Opuntia moniliformes, Lemaireocereus hystrix,Pilosocereus polygonus, and a few Prosopis juliflora.Shrubs include Caesalpinia sp., Cordia spp., Isidorealeonardii, Bursera brunei, Comocladia dodonaea,Harrisia nashii, Cylindropuntia caribaea, Guaiacumsanctum, G. officinale, and Tournefortia stenophylla.

Natural dry forest of the Barahona Peninsula. Thishabitat, occurring south of the Oviedo-Pedernalesroad, and on Isla Beata, Parque Nacional Jaragua,

consists of a mixture of coastal lowland and typicaldry forest with high endemism. Soils are dominatedby dogtooth limestone formations with little accumu-lation of alluvial deposits except for low lying zones,depressions, and rock cavities. Annual rainfall rangesfrom 630-800mm. On the western boundary, vegeta-tion is open and low (5-8m) on limestone rocks, whilein the more humid eastern areas, the same vegetationgrows more densely and reaches 6-12m. Commonplants include Metopium brownei, M. toxiferum,Acacia scleroxyla, Guaiacum sanctum, Burserasimaruba, Plumeria obtusa, Senna atomaria,Capparis cynophallophora, Haitiella ekmanii,Thouinidium inaequilaterum, Coccoloba pubescens,Cameraria linearifolia, Catalpa punctata, Opuntiamoniliformis, Tabebuia ostenfeldi, Phyllostylon rham-noides, Comocladia dodonaea, and Lonchocarpuspycnophyllus.

Semideciduous to transitional semihumid broad-leaved forests. These forests occur along the east andwest coasts of Parque Nacional del Este, and the west-ern portion of Isla Saona. Low coastal forests typi-cally occur on reef limestone, with annual rainfall upto 1,300mm, and 25-60% vegetation cover. Plantspecies include Jaquinia arborea, Coccoloba diversi-folia, Conocarpus erectus, Guapira brevipetiolata,Coccoloba uvifera, Borrichia arborescens, Burserasimaruba, Plumeria obtusa, Pilocereus polygonus,Erythoxylum arcolatum, Widelia calicina, Capparisflexuosa, C. cynophallophora, Guaiacum sanctum,and Metopium brownei. Tall semihumid broadleavedlimestone forest is characterized by a mosaic of forestpatches with varying canopy heights, depending onsoil conditions and depth of the water table.Vegetation cover ranges from 25% to 60%, with acanopy dominated by Clusia rosea, Bucida buceras,Coccoloba diversifolia, Bursera simaruba, Krugio-dendrum ferreum, Celtis trinervia, Metopiumbrownei, Sideroxylon foetidissimun, Swieteniamahogany, Ottoschulsia rhodoxylon, Guaiacum sanc-tum, and Bumelia salicifolia. The forest floor is dom-inated by Zamia debilis, with Peperomia epiphytesand vines. Leaf litter and a layer of humus coversrocks. Iguana localities with more mesic conditionsare known but these are the exception.

Like other rock iguanas, rhinoceros iguanas arediurnal, spending the night in retreats. Rock crevices,caves, burrows dug in soil or sand, and hollow trunksare also used during the day for resting, cooling, orsheltering. Males defend territories containingretreats attractive to females. High trees and exposedrocks are used by males for basking and overseeingdefended areas. Mating takes place at the beginningof or just prior to the first rainy season of the year.

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Females lay from 2 to 34 eggs, with an average clutchsize of 17 (J. Ottenwalder, unpublished data).Females guard nests for several days after laying, andincubation lasts approximately 85 days. Hatchlingsweigh about 51g, with a mean SVL of 104mm andtotal length of 288mm. Females probably becomesexually mature at 2-3 years of age. Rhinoceros igua-nas feed on fruits, leaves, and flowers of a variety ofplants, depending on availability. Additional informa-tion on their ecology and natural history is summa-rized by Schwartz and Henderson (1991).

HabitatIn the Dominican Republic, roughly 35% of rhinocer-os iguana habitat has been lost, and approximately75% of what remains is disturbed. Both figures aremuch higher for Haiti. Only the natural communitiesof Isla Beata have been spared noticeable impacts, andextensive dry forest stills remain in Parque NacionalJaragua. Most of the currently occupied habitat ischaracterized by fragmented forest patches, includingMontecristi, Samana Peninsula, Peninsula de laAltagracia, including Parque del Este and Isla Saona,Llanura de Azua-Bani, Valley de Neiba, and Peninsulade Barahona.

In Haiti, conditions are more critical, and extensiveareas of previously diverse plant associations are nowdominated by disturbed Prosopis juliflora-Acaciamacracantha communities. Large areas of originalforest have been extirpated and desertification is pro-gressing rapidly. Among the localities containinghabitats supporting iguana populations until the late1970s are Tortue Island, Riviere Saline, Plaisance,Mole St. Nicolas, Anse Rouge, Gonaives to St. Marc,Gonave Island, Ile Petite Gonave, Mirebalais,Miragoanne to Jeremie, Les Anglais, Cap St. George,Jacmel to Marigot, Belle Anse, Marigot to Anse-aPitres, and Lake Etang Saumatre in the Cul-de-Sacregion (Ottenwalder and Meylan, unpublished manu-script).

ThreatsHabitat destruction, due to extraction of hardwoodsand fuelwood, charcoal production, agriculture, live-stock grazing, and limestone mining, represents themajor threat to rhinoceros iguanas in both theDominican Republic and Haiti. In the DominicanRepublic, about 13% of the human population (± 1million) occupy dry forest regions. These areas arealso the most economically depressed, and exploita-tion of forest habitats for charcoal and fuelwood rep-resent important sources of income. About 75-80% ofthe total national demand for these products originatesfrom dry forest habitats.

Other important threats are predation by feral dogs,

cats, mongoose, and pigs on adults, juveniles, andeggs, and illegal hunting of subadults and adults forfood and local trade. The use of iguanas for food inHaiti is extreme in rural areas where iguanas are con-spicuous enough that local people are familiar withthem. International trade of wild animals fromHispaniola, a conservation problem until the mid1980s, has been controlled in the Dominican Republicunder CITES since 1987, but no such control exists inHaiti.

Current conservation programsIn the Dominican Republic, most rhinoceros iguanapopulations are either fully or partially protectedinside existing national parks and reserves. Protectedareas supporting iguana populations includeMontecristi National Park, Parque Nacional del Esteincluding Isla Saona, Parque Nacional Jaragua includ-ing Isla Beata, Las Caobas Strict Natural Reserve, ElAcetillar scenic area, Sierra Martin Garcia NationalPark, and Lago Enriquillo National Park, includingIsla Cabritos. However, the foothill regions in the lat-ter two areas remain only partially protected.Management in most protected areas is not intensive,and in some cases is restricted to legislation.

A number of fragmented populations are found out-side protected areas, primarily in the CibaoOccidental Valley, Samana Peninsula (part of the pro-posed Samana Bay Biosphere Reserve), the drycoastal portion of the Altagracia peninsula, Las Tablasof Bani, Peravia Province, west to Llanura de Azua,the eastern half of the Neiba Valley, including thenortheastern slopes of Sierra de Bahoruco aboveCabral Lagoon, the lowlands of Puerto Alejandro, andthe southern slopes of Sierra Martin Garcia near Bahiade Neiba, the drier slopes of the eastern half of Sierrade Bahoruco, and the dry forest region north of thePedernales-Cabo Rojo-Oviedo road.

Compliance with international trade regulations iseffective, aside from occasional smuggling of animalsacross the border with Haiti. Rhinoceros iguanas areprotected nationally by Dominican wildlife regula-tions. Enforcement has improved during the past fewyears, but clearing of the natural habitat for develop-ment is not being prevented, and illegal hunting andpoaching for food and for the local pet market contin-ues. No formal protected areas are known within thepresent distribution of iguanas in Haiti. The status ofprotective legislation is also uncertain, although therhinoceros iguana was included on a list of protectedwildlife by the Ministry of Agriculture during the1980s. Enforcement of any potentially existingwildlife regulations seems unlikely at present.

Rhinoceros iguanas are the most common rockiguana in captivity. A successful breeding program

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existed at the Parque Zoologico Nacional of theDominican Republic (ZooDom) from 1974 to 1994,with an average of 100 young hatching annually.These efforts included experimental reintroductionsof captive-bred young to several protected areas in thesouthwest Dominican Republic. Although a captivecolony of almost 300 iguanas representing all ageclasses was maintained at ZooDom until December1994, the program was adversely affected by adminis-trative changes. In recent years, the captive breedingand conservation program has been gradually and suc-cessfully reactivated.

As of November, 1995, rhinoceros iguanas else-where in captivity included 39.32.36 individuals atabout 20 zoological institutions, with an additional5.3.3 animals of unassigned subspecies, reported byseven American Zoo and Aquarium Association insti-tutions (Christie, 1995). The actual number may behigher considering holdings at some European zoosand many private collections.

Critical conservation initiatives• Strengthening of current regulations and legis-lation protecting iguana populations by increas-ing fines and designating selected areas as criti-cal habitat whether outside or inside existingprotected area boundaries.• Development of educational awareness cam-paigns to promote iguana conservation, particu-

larly to discourage subsistence hunting of igua-nas for food, local trade, and habitat conversionfor charcoal production.• Development of a national conservation andrecovery strategy and working group to includegovernment agencies, non-governmental conser-vation organizations, and iguana researchers.• Establishment of research, management, andmonitoring programs for wild populations andcritical habitats.• Involvement of local organizations and com-munities in all iguana conservation, education,and research activities.

Priority projects1) Assess the current status of wild populations andremaining habitats throughout the species' range.

2) Investigate natural history and ecology, habitat use,and factors limiting numbers in order to develop aconservation strategy and recovery plan for thespecies. Such studies should be concentrated in areaswhere rhinoceros iguanas are sympatric with Ricord'siguanas.

3) Control or eradicate exotic predators and herbivorecompetitors on Isla Cabritos in Lago Enriquillo andIsla Beata.

Fig. 3. Recent distribution of the rhinoceros iguana on Hispaniola. Localities for Haiti consist of survey datagathered between 1977 and 1985 (P. Meylan and J. Ottenwalder, unpublished) and may not represent the fullextent of available suitable habitat existing today.

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Contact personsJose OttenwalderUNDP/GEF Dominican Republic Biodiveristy ProjectUnited Nations Development ProgramPO Box 1424, Mirador SurSanto Domingo, Dominican RepublicTel: (809)534-1134Fax: (809)530-5094E-mail: [email protected]

Angelica EspinalDepartamento ZoologiaParque Zoological Nacional (ZOODOM)Santo Domingo, Dominican Republic

Sixto Inchaustegui and Ivon AriasGrupo Jargua, Inc.El Vergel 33Santo Domingo, Dominican RepublicTel: (809)472-1036Fax: (809) 412-1667E-mail: [email protected]

Departamento de Vida SilvestreSubsecretaria de Rescursos NaturalesSecretaria de Estado de AgriculturaSanto Domingo, Dominican Republic

Mona Island iguanaCyclura cornuta stejnegeri

By Thomas Wiewandt and Miguel Garcia

DescriptionThe Mona Island iguana is a large, robust member ofthe genus. Adult males and females average 517 and475mm SVL, and 6.1 and 4.7kg body mass, respec-tively. Both sexes are ornamented with protrudingfacial scales and a horn-like, conical scale atop thesnout. Also typical of adults are huge, sagging jowlmuscles and two prominent pads of fatty connectivetissue crowning the head. Body coloration is a uni-form gray, olive, or brown in adults. Hatchlings arelight gray or tan with dark bands.

At the conclusion of his three-year study, T.Wiewandt (1977, 1982) chose to retain the name C.stejnegeri for this taxon (Barbour and Noble 1916) onthe basis of significant differences between the repro-ductive biologies of the Mona population and its clos-est living relative on Hispaniola, the rhinoceros igua-na, C. cornuta cornuta. In their 1977 revision of thegenus, Schwartz and Carey renamed the Mona popu-lation C. cornuta stejnegeri based on scale counts of

about a dozen individuals of mixed age and sex.Further investigation of all populations in question isclearly needed before meaningful subspecies/speciesdesignations can be made. M. Garcia is planning adetailed investigation of systematics in the cornutacomplex which should help resolve taxonomy withinthis group.

DistributionThe Mona Island iguana is endemic to the remoteisland of Mona, a low-profile limestone plateau situ-ated midway between Puerto Rico and Hispaniola.The 11 by 7km island lies within a deep sea channelknown as the Mona Passage, and present submarinebanks offer no evidence of former connections witheither Puerto Rico or Hispaniola. Mona is part of theCommonwealth of Puerto Rico, administered as a nat-ural reserve by the Division of Natural Reserves andRefuges within the Puerto Rico Department ofNatural Resources and the Environment (PR-DNRE).Mona Island has been designated as a NationalHistorical Landmark. The U.S. Fish and WildlifeService provides some funding for projects related tohunting, fishing, and endangered species. The entireisland is occupied by iguanas, and the soil-rich coastalterraces and inland sinkhole depressions are essentialfor reproduction (Fig. 4).

Status of population in the wildBased on island-wide surveys conducted from 1972 to1975, T. Wiewandt calculated a mean density of igua-nas on Mona of 0.33/ha and an estimated minimumpopulation size of 2,000. A follow-up census was car-ried out by J. Moreno in late March and early April,1995. Moreno's estimate of 1,155 individuals sug-gested to him that the Mona population had declinedover the past 20 years. However, there were signifi-cant differences in methodology between the two sur-veys. Wiewandt utilized a transect width of 12m,whereas Moreno utilized a transect width of 16m.Had Moreno assumed a 12m transect width, his pop-ulation estimate would rise to 1,540. Conversely, hadWiewandt assumed a 16m transect width, his popula-tion estimate would drop to 1,500. It is important tonote that because these iguanas have greatly staggeredactivity patterns, varying between seasons and indi-viduals, the population could conceivably be twice theestimated size. Meaningful comparisons will requireestablished guidelines for future surveys, defined bylocation, time of day and year, weather conditions,and number of trained observers.

No matter how current census figures are interpret-ed, it is clear that the Mona iguana population isabnormally small. A survey of the similarly-sized rhi-noceros iguana on Petite Gonave Island in Haiti indi-

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cated densities 26 times greater than those found onMona (P. Meylan, personal communication). T.Wiewandt found that immature iguanas were scarceon Mona, representing only 5-10% of the population,and J. Moreno sighted only two juveniles among 118iguanas seen. This contrasts sharply with M. Garcia'sunpublished data for rhinoceros iguanas (C. cornutacornuta) on Isla Beata in the Dominican Republic,where all age classes are abundant and juveniles com-prise approximately one-third of the population (seeGrupo Jaragua, 1994). Low iguana densities and thescarcity of juveniles on Mona suggest a senescent anddeclining population.

Ecology and Natural HistoryMona's climate is dry subtropical (800mm rainfall peryear), supporting an open canopy forest of short, sea-sonally deciduous trees, shrubs, cacti, and bromeliads.Rainwater percolates rapidly through the porous lime-stone substrate, allowing no freshwater streams orponds. Solution channels and sinkholes that penetratethe island's rock topography offer underground shel-ters that are utilized by both male and female iguanas,and retreats attractive to females are vigorouslydefended by males. Some males hold territories year-round, while others defend them only during the briefJune mating season.

Because more than 95% of Mona's surface is rock,females must migrate to scarce soil deposits for nest-ing. The onset of the two-week, mid-summer nestingseason appears to be cued by photoperiod and femalesare especially wary at this time. Most egg laying(74%) occurs in sandy clearings on the island's south-ern coastal terraces, with the remaining 26% in sink-hole depressions (Haneke 1995). Nesting femalesfight over favored nest sites and defend completednests. Mean clutch size is 12 eggs. Surviving eggshatch approximately 83 days after laying, during thelatter half of October. Newly emerged young are largeand only the smallest juveniles are susceptible toindigenous predators. Coloration and behavior ofhatchlings suggests that aerial predators have longbeen a threat to this age class (Wiewandt 1977).

Juvenile iguanas are slow-growing, and femalesrequire 6 to 7 years to reach sexual maturity.Although longevity records are not available, Monaiguanas, like all large rock iguanas, are probablyamong the longest lived lizards in the world.Consequently, populations are slow to recover fromlosses over time.

Mona iguanas are primarily herbivorous, with astrong preference for fruits that fall from native trees.Some animal matter is eagerly taken, especially cater-pillars when available. Trees reach their greatest sizeand diversity in scattered sinkhole depressions, areas

that are of particular importance to the welfare of theiguana population.

HabitatDuring his surveys, T. Wiewandt sighted iguanas onMona's plateau at a density of 0.8/km traversed,except on routes along major escarpments and cliff-side talus slopes, where iguanas were three to fourtimes more numerous. In contrast, iguanas were rareon much of the island's flat, sandy southwesterncoastal terrace, presumably because natural food andshelter are scarce there. Roughly half of the area hasbeen cleared and reforested in mahogany andCasuarina trees, which are of little value to the igua-nas because they shade out native understory and bearno edible fruits. Iguana density rises dramatically onthis terrace during the summer nesting season whenfemales migrate to coastal lowlands in search ofsandy, sunlit clearings (Wiewandt 1977; Haneke1995).

Historically, Mona's iguanas have been adverselyaffected by man for centuries, dating back to land usepractices of pre-Columbian indians and continuing tothe present (Wadsworth 1973). People settling sub-tropical dry limestone islands have traditionally con-centrated their activities near beaches and within soil-rich sinkhole depressions, thereby inadvertently dis-rupting the life cycle of iguanas during nesting andhatching. Although there are presently no permanenthuman residents on Mona, a variety of domestic ani-mals inhabit the island, including feral goats, pigs, andcats.

ThreatsThe most pressing conservation management chal-lenge on Mona today is that of exotic species. Havingevolved in the near absence of predators, insular igua-nas lack the behavioral and demographic attributes tocope with introduced mammals. Feral pigs regularlyplunder iguana nests. Nesting females are unable toprotect their eggs from pigs and will cover an emptynest with soil, not recognizing that their eggs aregone. The extent of pig predation in any given yearappears to be correlated with nest location and totalrainfall during the three months prior to nesting. T.Wiewandt found that along the south coast nest lossranged from 65-100% in the driest year to less than5% in an unusually wet year. Haneke's (1995) com-parison between coastal and inland nest sites revealedcomplete failure of all inland nests surveyed. Coastalnesting attempts were more successful, with the high-est success in areas protected by pig-proof fences.

Feral cats are also present on Mona, and constitutethe most serious threat currently impacting youngiguanas. These elusive predators are extremely diffi-

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cult to study and control. Their dietary preference forsmall reptiles has been established (Wiewandt 1977)and their interest in young Mona iguanas observed(Moreno 1995). The devastating impact of cats on apopulation of Turks and Caicos iguanas was clearlydocumented (Iverson 1978), and there is little doubtthat the present scarcity of juveniles on Mona is dueprimarily to the combined effects of pigs consumingeggs and cats preying on young.

Over 20 years ago, botanist R. Woodbury expressedconcern that most of Mona's sinkhole depression for-est trees appeared unable to propagate successfullybecause of intense browsing pressure by feral goats.A follow-up study of forest regeneration within afenced study plot (Cintron 1976) confirmed theseobservations, noting not only a marked increase in thenumber of native tree seedlings during the first year,but also a 100% increase in accumulated leaf litterwithin the enclosure. Despite higher than normalrainfall that year, recovery of the plant communitywas slower than expected. Cintron and Rogers (1991)further note that successional patterns island-wide arebecoming skewed toward toxic, unpalatable plantspecies. Within depression forest communities,unpalatable shrubs and trees are starting to dominatethe understory and also predominate in secondarygrowth on the plateau in places that were burned orcleared of vegetation during the past 60 years(Wiewandt 1977). Fortunately, Mona's trees are long-lived, allowing them to continue to survive despiteheavy browsing pressure. Mona's history of humanoccupation suggests that goats and pigs were intense-ly hunted for food by island residents as late as 1942(Wadsworth 1973). Consequently, much of the dam-age to vegetation evident today may be relativelyrecent (Wiewandt 1977).

Although lacking permanent settlements, Mona is ahaven for recreational activities, including camping,fishing, swimming, scuba diving, beach combing,exploring, and hunting. Most of these activities areconcentrated along the island's sandy coastal terracesand within sinkhole depressions, areas of criticalimportance for iguana nesting. Haneke (1995)observed that new camping facilities had been recent-ly added in iguana nesting areas at Playa de Pajaros.Mona iguanas are wary and easily disturbed whilenesting, and visitors can unintentionally disrupt theegg-laying process. People and feral animals walkingthrough nest site clearings during incubation maycause nest chambers to capsize, denying oxygen todeveloping eggs. These and other conflicts betweeniguanas and visitors are bound to intensify as recre-ational use of the island continues to expand. Goatsregularly gather in sinkhole depressions on Mona'splateau, and this may partially explain Heneke's

(1995) observation of complete nest failure there.Mona may have already exceeded its carrying capaci-ty for low impact tourist visitation. Better supervisionover visitors, particularly by strengthening education-al programs, will become increasingly important asthe number of people coming to Mona continues togrow.

Another recent concern for conservation of Monaiguanas is the emergence of an undefined disease orparasite that causes blindness. Throughout T.Wiewandt's three-year study, only one animal withcloudy eyes that was obviously blind and emaciatedwas found. Recently, Haneke (1995) observed 15blind adults on Mona, all with opaque, bluish eyes andapparently severely undernourished. Ramos (1964;cited in Kuns et al. 1965) lists 16 species of eye flies(family Chloropidae) occurring on Mona, includingHippelates pusio, which has been incriminated in thespread of catarrhal conjunctivitis in the United States.Studies are urgently needed to identify potentialpathogens and vectors responsible for blindness in theMona iguana population.

Current conservation programsThe Mona iguana is listed as threatened by the U.S.Fish and Wildlife Service and the PR-DNRE. In1984, the U.S. Fish and Wildlife Service approved arecovery plan for the Mona iguana prepared by C.Diaz, PR-DNRE (Diaz 1984). Bringing feral pig andgoat populations down to ecologically tolerable levelsand maintaining them there would require that 50-70% of each population be removed annually (Bakerand Reeser 1972), an extremely costly undertakingthat would be a monumental task in Mona's ruggedterrain. Realistically, these animals will never be trulybrought under control.

During the last 25 years, the PR-DNRE has insti-tuted some important changes. The hunting season onMona has been moved to a time outside the iguananesting and incubation seasons. Together with thelocal herpetological society, Sociedad Chelonia, thegovernment has created several new nesting areas onthe southwestern coastal terrace. A number of clear-ings in the Casuarina forest have been established thatare fenced off from goats and pigs but allow iguanasto pass freely. Iguanas have been observed nestingsuccessfully in the new clearings (Chelonia 1993).Fencing of remote nest sites (two 20m x 15m plots) iscurrently being undertaken by the PR-DNRE, the U.S.Fish and Wildlife Service Caribbean Office, the U.S.Coast Guard, the Sociedad Chelonia, and the ToledoZoo. Researchers at the PR-DRNE and the ToledoZoo have additionally begun to assess the nature ofthe blindness syndrome seen in several adult iguanas.For his graduate research, N. Perez, University of

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Puerto Rico, will be measuring overall populationsize, studying recruitment and survivorship of juve-niles, quantifying egg loss to pigs and rats, and deter-mining the effect of exotic vegetation on incubation ofiguana eggs. A total of 33 blood samples from wildiguanas has been provided to S. Davis for phylogenet-ic analysis. Over the years, feral cats have occasion-ally been trapped or shot on Mona. Currently, PR-DNRE is conducting a long-term study to quantify theimpact of feral cats on Mona Island wildlife.

Critical conservation initiatives• Enforcement of existing laws for protection ofwildlife and other natural resources.• Implementation of an active and long-termeducational campaign about Mona Island and theconservation of its natural, environmental, andhistorical resources.

Priority projects1) Determine the cause of blindness in wild Monaiguanas by pathology examinations of afflicted ani-mals.

2) Monitor and continue to repair existing feral mam-mal control fences, and expand the fencing programby installing new goat and pig exclosures for sinkholedepressions utilized by nesting iguanas. Care must betaken to locate fences in places that will neitherdestroy Taino archeological sites nor mar the intrinsicbeauty of these areas.

3) Continue to evaluate Mona's plant communities inconjunction with construction of pig and goat exclo-sures around sinkhole depressions.

4) Expand educational programs for visitors and mon-

itor their activities on Mona.

5) Make follow-up field assessments in order to allowmeaningful comparisons between past and presentconditions on Mona to be made and to facilitate estab-lishment of a viable population. This work could offereducational opportunities for island personnel.

6) Establish a rigorous procedure for yearly censusingof the iguana population.

Contact personsThomas WiewandtWild Horizons, Inc.PO Box 5118Tucson, AZ 85703 USATel: (520)743-4551Fax: (520) 743-4552E-mail: [email protected]

Miguel GarciaBureau of Fisheries and WildlifePR-DNRE, PO Box 9066600San Juan, Puerto Rico 00906Tel: (787)722-7517Fax: (787) 724-0365E-mail: [email protected]

Jorge MorenoInstituto de Educacion Ambiental (INEDA)Universidad MetropolitanaApartado 21150Rio Piedras, Puerto Rico 00928E-mail: [email protected]

Fig. 4. Map of Mona island showing known nestingareas and major iguana habitat zones.

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Robert Matos, ChiefDivision of Natural Reserves and RefugesPR-DNREPO Box 9066600San Juan, Puerto Rico 00906Tel: (787) 723-6435Fax: (787) 724-0390

Jose Luis ChabertBureau of Fisheries and WildlifePR-DNREPO Box 9066600San Juan, Puerto Rico 00906Tel: (787) 722-7517Fax: (787) 724-0365

Nestor PerezUniversidad de Puerto RicoDepartamento de BiologiaPO Box 22360San Juan, Puerto Rico 00931Fax: (787) 764-2610E-mail: [email protected]

Andros Island iguanaCyclura cychlura cychlura

By Sandra Buckner and David Blair

DescriptionThe Andros Island iguana is a large rock iguana whichattains a total length of close to 1500mm (Auffenberg1976). The subspecies is dark-gray to black, with yel-lowish green or orange tinged scales on the legs, dor-sal crest, and particularly the head. With maturity, theyellow slowly changes to orange-red, especially inlarge males (Auffenberg 1976).

DistributionThis subspecies is found on Andros Island on thewestern edge of the Great Bahama Bank. Andros isthe largest of the Bahamian islands with an area of5,959km2 and a human population of 8,000-9,000concentrated in the eastern coastal region. Androsiguanas are scattered through North Andros,Mangrove Cay, and South Andros, which are separat-ed from each other by the North, Middle, andSouthern Bights. The subspecies range is ill-definedwith only assumptions and speculations available as toits status. North Andros, with extensive pine barrensand blue holes and creeks, is the area where mostsightings of iguanas currently occur. This is the morepopulated area where old logging roads allow access

to the interior. According to Auffenberg (1976),"though historically found over all of Andros, iguanasare now largely restricted to the western two-thirds ofthe island group, with the range becoming generallybroader southward. They reach maximum abundanceand size at the present time in the 'pine-yards,' partic-ularly where they are broken into small islands sepa-rated by extensive low mangrove and marl flats."

Status of populations in the wildWhile estimates put the wild population at 2,500 to5,000 distributed in three or more subpopulations(Hudson et al. 1994), these figures could be much toooptimistic as only occasional animals are observed,and these in scattered locations. Alternatively, due tothe remoteness and difficulty in accessing much of theregion, large subpopulations could be encountered,particularly in the central and southern regions of theisland and in the western reaches of north Andros.

Ecology and natural historyWhile it is expected that the natural history of these igua-nas is similar to that of the other two C. cychlura sub-species, no in-depth research studies have been conducted.

HabitatThe Andros rock iguana is the only iguana in theBahamas that is not now confined to small cays. Onepreferred habitat of this subspecies is under the opencanopy of the pine barrens (Pinus caribaea var.bahamensis), which offers a variety of fruits, flowers,and leaves of plants suitable for consumption by rockiguanas. The karst rock provides suitable retreats.

ThreatsIn the absence of any detailed research, the majorthreat to the Andros Island iguana is the proliferationand expansion of the range of feral pigs. While this isrecognized both locally and nationally, appropriatemethods of control have yet to be determined.Particularly in north Andros, feral pigs pose a veryreal threat to the recruitment of iguanas as they areknown to rout out eggs from iguana nests. Feral anddomestic dogs are also a threat to both juvenile andadult animals. The status and degree of threat posedby feral cats on Andros is unknown. Many local resi-dents are apparently unaware of the protected status ofthe Andros iguanas and may occasionally take themfor human consumption.

Current conservation programsLike all Bahamian rock iguanas, this subspecies isprotected in the Bahamas under the Wild AnimalsProtection Act of 1968. However, no areas have beenspecifically designated for the protection of iguanas

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on Andros and no specific conservation programs arein place.

There are currently no captive programs for thissubspecies. There is one old individual at ArdastraGardens and Zoo in Nassau. No one has been locatedwho recalls the iguana being brought to the zoo and asyet no records have been found. This iguana, firstobserved and photographed by S. Buckner in 1991,was still alive as of June, 1997. One large male, along term captive held by a private resident of SouthAndros, was still alive in 1984. Attempts to breed thisanimal have resulted in the death of at least two otheriguanas, presumably females.

Critical conservation initiatives• Education of local people regarding the pro-tected status of this iguana and its vulnerabilityto introduced mammals, particularly dogs andpigs.• Institutional strengthening of responsible agen-cies to develop enforcement capabilities.• Protection of suitable iguana habitat and possi-ble relocation sites.• Initiation of a national education program fortourists and residents.

Priority projects1) Determine the status of the population and itsrange, including the existence of viable subpopula-tions on south Andros.

2) Conduct ecological studies and collect natural his-tory data, ideally with the involvement of local resi-dents.

3) Establish captive breeding programs.

4) Institute control measures for introduced species.

Note: Conducting comprehensive research on Androswill be both logistically difficult and time consuming.The northern part of north Andros has old loggingroads that would enable access by appropriate vehi-cles. Over the rest of Andros, lack of roads or eventracks, myriads of mangrove islands, swamps andvery shallow waterways make travelling in all but theeastern coastal region extremely difficult and haz-ardous. In terms of personal safety, it is not recom-mended at this time that a solo or even two-personparty attempt such a project in any part of Andros.Research trips might be conducted in conjunctionwith other projects such as ongoing research into theblue holes of Andros. Suitable vehicles, shallow draftboats, and other equipment would be required.

Contact personsSandra BucknerBahamas National TrustPO Box N4105Nassau, The BahamasTel: (242) 393-3821Fax: (242) 393-3822E-mail: [email protected]


Exuma Island iguanaCyclura cychlura figginsi

By Chuck Knapp

DescriptionThe Exuma Island iguana is often regarded as thesmallest of the three subspecies of C. cychlura.Although Schwartz and Carey (1977) list the animalas obtaining a maximum size of 315mm SVL, recentstudies by C. Knapp indicate that individuals occa-sionally reach 470mm and 3.25kg (Bitter Guana Cay)to 542mm and 8.15kg (Leaf Cay). Barbour (1923)describes the Exuma Island iguana as being conspicu-ously different from the other subspecies in havingtiny supranasals usually separated by a small, azygousscale and two pairs of prefrontals, the posterior pair ofwhich is greatly enlarged.

Coloration is variable between populations. Adultsfrom Bitter Guana and Gaulin Cays are dull gray-black with diffuse pale gray spots. The crest scalesare either white or a light red. The head scales areblack tinged with orange on the snout and infralabials(Schwartz and Carey 1977). Adults from Guana Cayare dull black with diffuse pale white ventral and gularcoloration. The upper labial, temporal, parietal,nuchal and ocular scales are light blue, while the dor-sal crest scales are either gray with red tinge or intensescarlet. Schwartz and Carey (1977) describe juvenilesas possessing approximately seven black bands whichbecome slightly diagonal laterally and alternate withpale gray bands. All bands are heavily mottled withsmall pale dots.

DistributionThe subspecies is known from seven small cays scat-

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tered over 80km throughout the central and southernExuma island chain of the Bahamas. Anecdotal infor-mation suggests additional inhabited cays, but verifi-cation is necessary. The determination of rangethrough historic records is problematic due to certaincays sharing multiple names (e.g., Guana = PricklyPear = Noddy). Bitter Guana and Gaulin Cays con-stitute the northern extent of the population. Fourcays, White Bay, Noddy, North Adderly, and LeafCays, all located northeast of Norman's Pond Cay,compose the nucleus of the range. Guana Cay, south-west of Great Exuma, forms the southern boundary ofthe population.

Status of populations in the wildThe exact size of the total population is not known.Formal surveys using standardized transect tech-niques have been conducted only on Guana, Gaulin,and White Bay Cays (Carey, 1976; Windrow, 1977; C.Knapp, unpublished data). The extent of the remain-ing population is based on estimations of iguana den-sities through comparative observations (J. Iverson,unpublished data; C. Knapp, unpublished data).Standardized and subjective survey techniques esti-mate the population to be between 1,000-1,200 ani-mals.

While the majority of subpopulations appear rela-tively stable, some are in need of monitoring. Barbour(1923) refers to Bailey's collecting expedition onBitter Guana Cay, from which the holotype specimenwas procured, noting that "the iguana was foundabundant on the Cay, no less than nineteen beingtaken in an hour or so." Three surveys of Bitter Guanain 1993, 1995, and 1997 yielded only seven total igua-na sightings. Conversations with yachtsmen familiarwith the area confirm that the iguanas are being takenas a food source.

Ecology and natural historyExcept for the Guana Cay population, few formal nat-ural history studies have been conducted. The GuanaCay population was studied in the 1970s (Wilcox et al.1973; Carey 1976; Windrow 1977; Coenen 1995) andis currently being reinvestigated along with the otherremaining populations (Knapp 1995; 1996).

Adult iguanas are herbivorous, and are arboreal aswell as terrestrial feeders. Preferred food items areseasonally dependent and primarily consist of flowers,fruits, young buds, and leaves of Rachicallis ameri-cana, Reynosia septentrionalis, Strumpfia maritima,Jacquinia keyensis, Erithalis fruticosa, Coccolobauvifera, Coccothrinax argentata, Eugenia axillaris,Suriana maritima, and the rotting fruit of Casasiaclusiifolia (Windrow 1977; C. Knapp, unpublisheddata). Coenen (1955) reports the iguanas as

coprophagous. They actively forage for the feces ofthe zenaida dove, Zenaida leucocephala, and thewhite-crowned pigeon, Columba leucocephala.

The iguana populations exhibit an unusual socialsystem for the genus, displaying neither territorial norhierarchical behavior. Carey (1976) suggests that thisrelaxed social structure allows the population toremain dense under conditions of limited resources.He further states that a hierarchical social system onsmall cays would retard genetic variation by restrict-ing prime nesting sites, food supplies, and retreats toa few dominant animals. Adult iguanas have beenseen basking in large aggregations without evidenceof aggression towards conspecifics throughout themajority of their range (C. Knapp, unpublished data).At times, the iguanas demonstrate assertive and/orchallenge displays in the form of headbobs. Theseusually only occur when one lizard violates the spaceof another or during sex recognition. When minorskirmishes do occur over preferred food items, thelargest animal is always victorious (Windrow 1977;Coenen 1995).

Nesting has been observed on Guana Cay, withfemales digging a nest burrow approximately 61cmlong and 8-13cm deep. Gravid females will activelydefend an incomplete tunnel from conspecifics butwill not defend the nest site after oviposition. Theonly excavations of nest chambers revealed three eggseach in two nests (Coenen 1995).

HabitatThe Exuma Island iguana utilizes a variety of habitats,including sandy beaches, xeric limestone devoid ofvegetation, and areas of vegetation with or withoutsand or rock substrates. Limestone crevices and sandburrows are used as retreats at night and in adverseweather conditions. Presently, habitat appears to berelatively secure as cays supporting iguanas are smalland free from human settlement. However, recentobservations on White Bay Cay uncovered trailshacked through the interior and coconut palms plant-ed on the beach. The island is currently for sale andin danger of tourist development.

ThreatsConversations with locals suggest that removal of ani-mals from their home cays for tourist attractions else-where could constitute a significant threat. Althoughsuch activities probably occur on a small scale, theymay reflect the larger problem of smuggling of igua-nas from the Bahamas for illegal wildlife trade. Somecays are visited regularly by locals and yachtsmen,and dog tracks have been observed on Bitter GuanaCay. In addition to possible hunting pressure, preda-tion by dogs may be contributing to the apparent

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decline of that population. In 1981, J. Iverson report-ed the presence of rats on Gualin Cay; this was subse-quently confirmed by C. Knapp in 1995 (unpublisheddata). The effect of rats on this population isunknown, but past research indicates the detrimentalconsequences of rats on island reptiles (Cree et al.1995). Certain cays possess diminutive nesting sitesand the possibility of a season's recruitment beingdecimated by severe weather conditions is genuine.

The isolation of iguana-inhabited cays creates aproblem for consistent population monitoring.Discrete environmental events including hurricanescould endanger certain populations. For example,Hurricane Lily engulfed Great Exuma and her satellitecays on 18 October 1996. The effects of Lily on theGuana Cay iguana population were not observed untilMay, 1997 (S. Buckner, personal communication).

Current conservation programsAll Bahamian rock iguanas are protected under theWild Animals Protection Act of 1968. C. Knapp iscontinuing field surveys to assess current populationsand to better define the geographic distribution of thesubspecies. The Leaf Cay population was newly dis-covered in 1997. Blood samples are being collectedfrom each study population to establish genetic pro-files for different cays. Potential threats unique toeach cay are being documented in order to provide theBahamian government with information that will aidin setting conservation policies. Also, the vegetationand habitat condition on cays not currently supportingiguanas is being investigated for possible transloca-tion programs.

The Bahamas National Trust has erected signs onGualin Cay notifying the public of the protected statusof the iguanas. The Bahamian government currentlydoes not recognize any captive breeding programs,although unsanctioned breeding of these iguanas isapparently taking place in the United States.

Critical conservation initiatives

Priority projects1) Determine the status of the population throughoutits range.

2) Examine the possibility of translocations to othersuitable cays.

3) Carry out genetic studies on all populations.

4) Conduct ecological, behavioral, and natural historystudies on each population.

5) Establish a captive breeding program.

Note: The remoteness and inaccessibility of caysinhabited by iguanas makes field research expensiveand time-consuming. The John G. Shedd Aquarium iscurrently funding research but other avenues for sup-port need to be developed in order to accomplish theresearch goals in a timely manner.

Contact personsChuck KnappJohn G. Shedd Aquarium1200 South Lake Shore DriveChicago, IL 60605 USATel: (312) 939-2426Fax: (312) 939-8069E-mail: [email protected]


Robert EhrigFinca Cyclura29770 Mahogany LaneBig Pine Key, FL 33043 USATel: (305)872-9811Fax: (305) 745-8848E-mail: [email protected]

Allen's Cay iguana

Cyclura cychlura inornata

By John Iverson

DescriptionThe Allen's Cay iguana is a large (to 1000mm total

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• Establishment of additional national parks toafford iguana populations more protection.Additional wardens and funds will need to bemade available to patrol parks and monitor igua-na populations.• Implementation of an education program forlocals and cruising yachtsmen to inform peopleof the rarity of Bahamian iguanas. Such pro-grams should stress the detrimental impact thatdogs, cats, and smuggling exert on small iguanapopulations.• Continuation of efforts to instill in allBahamian citizens national pride regarding theirunique iguanas.

length) subspecies of C. cychlura characterized by alack of horn-like frontal or prefrontal scales, rostralscale in contact with the nasal scales, slightly enlargedprefrontal scales separated from frontal scale by fourscale rows, usually two portmental scales, and dorsumpigmented gray-black with cream, pink, or orangemottling. Pink or orange pigment is most obvious onthe posterior lower labial scales, the preauricularscales, and the enlarged mid-dorsal scale row.

DistributionOnly two breeding populations of this subspecies areknown, on Leaf Cay (4ha) and U Cay (also known asSouthwest Allen's Cay; 3ha) in the northern ExumaIsland chain in the Bahamas. Probably less than sevenadults also occur on Allen's Cay (7ha), but no evi-dence of breeding has been found there during 12years of study.

Status of populations in the wildBased on a 17-year mark and recapture study, approx-imately 130 subadult and adult iguanas (> 8 years old)occur on Leaf Cay and 100 on U Cay. Juvenile popu-lation estimates are not precise, but in March are prob-ably near 100 for each island. The entire wild popu-lation of this subspecies is less than 500 individuals.The populations have generally been stable over thepast 17 years, with recruitment occurring on bothislands every year. However, some removals fromLeaf Cay by poachers and Bahamian zoo and parkpersonnel are known to have occurred over the pastdecade. Although the two main populations are gen-erally stable, the two cays are heavily visited bytourists.

Ecology and natural historyMost of the details of the life history of this iguanaremain unstudied. What is known has been accumu-lated during approximately biennial visits by J.Iverson. During these trips, lizards have been markedand recaptured, primarily for growth and survivorshipstudies. These iguanas can apparently survive on thevery smallest rocky islets as long as sufficient vegeta-tion is present for food; however, areas of sand arenecessary for nesting. Hatched egg shells have beenfound on several occasions, but always in sandy areas.The lack of breeding on Allen's Cay may be due toinsufficient areas of exposed sand above tidal influ-ence.

Recapture studies have shown that Allen's Cayiguanas average about 113mm SVL (157mm taillength, 56g) in March at approximately six months ofage. Average growth rates are over 20mm SVL peryear during the first year, declining to about 15mm peryear by age 5.5 at about 206mm SVL (Iverson and

Mamula 1989; J. Iverson, unpublished). Growth infemales then begins to slow, whereas in males growthcontinues at the same rate until about 300mm SVL.The result is considerable sexual dimorphism in size.The largest known adult male was 476mm SVL andweighed 4.8kg, whereas the largest female was368mm SVL and weighed only 2. lkg. Large adults ofboth sexes usually grow less than 10mm per year.Males and females cannot be sexed externally, but canbe sexed fairly reliably by hemipenal probing. Basedon minimum age for adults first caught in 1980 andstill alive in 1992 and/or 1993, some of these iguanaslive beyond 25 years of age.

Allen's Cay iguanas are active diurnally, spendingthe night in burrows they have dug or in naturalretreats in or under rocks. They are primarily herbiv-orous, feeding on fruits, leaves, and flowers of most ofthe plants present on their tiny islands. They willclimb up into the vegetation to feed. They are alsoopportunistically carnivorous, as evidenced by crabclaws in their feces. In addition, humans regularlyfeed the iguanas (particularly on Leaf Cay) everythingfrom table scraps to fresh produce. The effect of foodsupplementation on the life history of these lizardsremains unknown, but deserves study.

Nothing is known about reproduction in thisspecies, but mating probably occurs in May, with egg-laying commencing in June. Jolly-Seber models ofrecapture data suggest that survivorship of subadultsand adults exceeds 90% per year. During the non-breeding season, these lizards appear to have domi-nance hierarchies rather than strictly defended territo-ries; however, this may be because tourists frequentlyfeed the iguanas on the main beach areas, perhapscausing a breakdown in the natural social system.Their behavior during the breeding season isunknown.

HabitatThe natural habitat of this iguana on Leaf and U Cayshas not been significantly disturbed by human activi-ty, even though a number of introduced ornamentalplants occur on these cays (e.g., Casuarina, lilies,palms). All potential habitats on both Leaf and UCays are occupied by iguanas, including some subop-timal areas of bare, honey-comb limestone.Additional habitat is available on Allen's Cay, butwithout sandy areas for nesting, the island apparentlycannot support a breeding population. Dredging ofsand from the harbor between Allen's Cay and LeafCay to upland areas on Allen's Cay could double thepotential habitat area for this iguana.

ThreatsThe only significant current threat to these popula-

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tions is the removal of iguanas by humans. The prob-lem is exacerbated by the fact that these cays offergood anchorage less than a day's sail from Nassau; forexample, during March, 15-20 yachts and 1-2 nativeboats are anchored there each night. Regular reportsof actual or attempted poaching are made to the war-den of the Exumas Land and Sea Park to the south. Inaddition, iguanas are occasionally removed for exhib-it purposes in Bahamian zoos, parks, and gardens.Illegal exploitation for international trade is undocu-mented, but probably occurs.

Current conservation programsThe Allen's Cays iguanas are protected nationallyunder Bahamian law, but enforcement is difficultwithout a warden present. The warden of the nearbyExumas Land and Sea Park can potentially respond toreports of poaching, but that is not always practical.Fortunately, signs erected on the islands explain thevulnerability of these lizards, and most visitors onyachts radio the authorities if anyone is seen harassingthe iguanas. Unfortunately, visitors also enjoy feed-ing them unnatural foods. Long-term investigationsof growth, survivorship, and population status of theseiguanas are ongoing by J. Iverson, but a study of theirreproductive ecology is urgently needed.

A few captive Allen's Cay iguanas are currentlymaintained at the Ardastra Zoo and Nature CentreDifferent on Abaco. Captive breeding is a goal, butlong-term plans for any offspring produced need to bedeveloped.

Critical Conservation Initiatives• Establishment of regular patrols to enforce pro-tection, prevent exploitation, and discouragefeeding of iguanas.• Initiation of a national education program fortourists and residents.

Priority projects1) Collect age-specific reproductive data on themarked population of Allen's Cay iguanas for whichlong-term growth data already exist.

2) Explore the feasibility of modifying sinkholes onAllen's Cay to create nesting habitat for iguanas.

3) Continued monitoring of the introduced populationon Alligator Cay

Contact personJohn IversonDepartment of BiologyEarlham CollegeRichmond, IN 47374 USATel: (317) 983-1405Fax: (317) 983-1304E-mail: [email protected]

Cuban iguanaCyclura nubila nubila

By Antonio Perera

DescriptionThe Cuban iguana reaches a very large adult size, witha mean SVL of 405mm for males and 320mm forfemales. This subspecies is usually gray in color,stippled or mottled with tan, and has a tan head andtail. Adults are somewhat greenish in color and maybe stippled with yellow. The juvenile pattern consistsof a series of five to ten pale chevrons which expandmid-dorsally to give a longitudinal series of subcircu-lar or subrectangular pale blotches. Between the paledorsal chevrons are black chevrons which form themargins of the lateral pale pattern. In adults, a con-spicuous feature is very high dorsal crest scales(Schwartz and Carey 1977).

DistributionThe Cuban iguana is well distributed around Cuba,mainly in xerophilic coastal areas, but relatively safepopulations are found only on some islets along thenorth and south coasts and in isolated protected areason the mainland. These include GuanahacabibesBiosphere Reserve in the west, Desembarco delGranma National Park, Hatibonico Wildlife Refuge,Punta Negra-Quemados Ecological Reserve, andDelta del Cauto Wildlife Refuge, all in eastern Cuba(Fig. 5). This subspecies has also been introduced toIsla Magueyes, southwest of Puerto Rico. Because ofits wide distribution, accurate information about thenumber of distinct subpopulations of Cuban iguanas iscurrently unavailable, yet it may be present on asmany as 4,000 islets surrounding the Cuban mainland.The population on the U.S. Naval Base atGuantanamo Bay has been estimated at 2,000-3,000individuals (A. Alberts and J. Phillips, unpublisheddata).

Status of populations in the wildNot many decades ago, the subspecies was extremelywidespread on Cuba. However, populations on the

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mainland have decreased dramatically or disappearedentirely in most areas since the end of the last centu-ry. On many islets, populations are still relativelysafe, but this situation is changing with the transfor-mation of many islets for tourist developments.Nevertheless, if strictly protected areas on the main-land and islets continue to remain untouched, 60 to80% of the remaining population will probably besafe. Any population analyses should be carried outwith two distinct components: one for populationsliving on the mainland, and one for populations inhab-iting small islands and islets.

Subpopulations of the Cuban iguana show greatvariation in density according to habitat quality andlevel of protection. On three natural, undisturbedislets, Perera (1985b) found densities of 25.01/ha;9.64/ha, and 4.42/ha. V. Berovides found densities of7.71/ha and H. Gonzalez found densities of between 9and 11/ha on Cayo Rosario. Those authors estimatethe total population of Cayo Rosario to be 10,000individuals. Recently, V. Berovides (personal com-munication) found a density of 40/ha on a rocky islet.The total population of this subspecies in Cuba is esti-mated at between 40,000 and 60,000 individuals.

In general, the population is declining, more quick-ly on the mainland than in other areas. Most disturb-ing is the rapidity of the loss of this subspecies in dis-turbed areas. Iguanas are now absent from the north-eastern Havana coast, the Hicacos peninsula, and KeyLargo, where they were known to be very abundantsome 30-40 years ago. Whereas habitat transforma-tion and disturbance on the mainland seem to beresponsible for local extinctions, populations appearstable on many untouched islands and islets.Mainland populations have probably been declining ata rate of greater than 1 % per year for the last ten years,primarily as a result of habitat alteration and interac-tions with domestic and feral introduced species,including cats, dogs, and pigs.

Ecology and natural historyCuban iguanas can be found in relatively undisturbedxerophilic coastal lands on both mainland Cuba andsurrounding islets, primarily in rocky limestone areaswhere natural refuges and appropriate nesting sites areavailable. Foraging is commonly observed in concen-trations of coastal mangroves. In western Cuba, thereis an isolated population inhabiting an inland karsticmountain area. Apparently, semiarid lands severalkilometers inland from the coast can still supportiguana populations.

The Cuban iguana is a phytophagous generalist,and the diversity of its diet depends on the floristicdiversity and abundance of vegetation in each locality.Perera (1985a) found 25 different vegetation types in

the diet of these iguanas. The most frequent plants(flowers, fruits, or leaves) in the diet wereAndropogon, Avicenia, Canavalia, Capparis,Chrysobalanus, Conocarpus, Eragrostis, Lagun-cularia, Opuntia, Rachilcalis, Rizophora, Sporobolus,Strumpfia, Suriana, and Thrinax. If readily availablewith little effort, Cuban iguanas will also feed on ani-mal matter. The most common animal item in the dietis the crab Cardisoma guandhumi. Some seasonalchanges in diet are evident, especially during the rainyseason when fruits from Opuntia, Chrysobalanus,Strumpfia, and Suriana become available.

Cuban iguanas reach sexual maturity at an age oftwo to three years. Reproductive behavior in this sub-species is similar to that described for other membersof the genus. Males become aggressive, and vigor-ously defend territories in competition for females.Females lay 15 to 30 eggs annually in a single clutchin a nest which they dig in the sand.

HabitatPreviously suitable habitats have been losing the con-ditions necessary to support iguanas since 1900.Many coastal areas with sandy beaches have been pro-gressively assimilated for tourist resort development.Although this process was initially restricted to themainland, in recent years many islets have been ren-dered unsuitable for iguanas for the same reason.Even if habitat is not lost directly, the disturbancesassociated with development appear severe enough tocause iguana populations to disappear in some areas.Fig. 5 shows the area presently occupied by Cubaniguanas. It is possible to identify 12 historical con-centrations of iguanas in the Cuban archipelago:

(1) Guanahacabibes peninsula: No major habitattransformation. The original distribution of iguanasremains basically unchanged, but density hasdecreased as a result of predation by feral dogs, cats,and pigs and local habitat destruction. In general, thearea retains its natural features.

(2) Canarreos subarchipelago, including Isla deJuventad: The best remaining populations are locat-ed in this area, although some local extinctions due tohabitat loss caused by fires or development of touristresorts have been reported on Cayo Largo. On Isla deJuventad, iguanas are still abundant along the southcoast and adjacent inland areas.

(3) Zapata peninsula: No major habitat transforma-tion. Iguanas are still abundant in coastal areas and onsurrounding islets. Density has declined in someareas as a result of predation by feral cats, dogs, andpigs and local habitat degradation.

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(4) South coast and islets of Sancti SpiritusProvince: In mainland coastal areas, iguana popula-tions are highly impacted or extinct. On some islets,iguanas are still very abundant.

(5) Jardines de la Reina subarchipelago: A well-pre-served subarchipelago with healthy populations ofiguanas on some islets.

(6) Delta del Cauto Wildlife Refuge: Iguanas areabundant in sandy areas of the delta as well as onmany islets.

(7) Desembarco del Granma National Park: One ofthe best preserved areas in the country which includesa marine limestone terrace system on which iguanasare particularly abundant.

(8) Santiago de Cuba and Guantdnamo semi-aridcoast: Although density has declined and distributionhas contracted in some areas due to habitat loss andthe introduction of exotic predators, good populationsremain in some protected areas.

(9) Holguin Province coast: As above, although den-sity has declined and distribution has contracted insome areas due to habitat loss and the introduction ofexotic predators, good populations remain in someprotected areas.

(10) Sabana-Camaguey subarchipelago and north-central coast of Cuba: This is the second major con-centration of iguanas. Although some local extinc-tions have occurred due to habitat loss (Hicacospeninsula) and other areas are under pressure fromtourist development, iguana populations are dense inprotected areas.

(11) Northeast Havana coast: Almost all populationsbecame extinct in the last 30 to 40 years as a result ofhabitat loss and transformation.

(12) Vinales: This is the only iguana populationknown to live inland. Iguanas inhabit some karstichills, but their density is very low in this habitat.

ThreatsHabitat transformation and human disturbance repre-sent the main threats to Cuban iguana populations.Other important threats include predation by wild anddomestic dogs on both adults and juveniles, predationby cats on juveniles, and egg predation by pigs.Hunting is not a major threat because there is not awidespread tradition of consumption of iguana meator eggs.

Current conservation programsWith the exception of area 11 above, all of the majoriguana concentrations are either partially or fully pro-tected. Fig. 5 shows strictly protected areas, resourcemanagement areas, and gaps where iguanas are pre-sent but formal protection is lacking. At selectedlocalities within the National System of ProtectedAreas, projects directed toward conservation andreproduction of Cuban iguanas are being carried outby the Centro Nacional de Areas Protegidas in collab-oration with researchers from Havana University.Ecological and systematic studies are being conduct-ed at the Institute of Ecology and Systematics, CubanAcademy of Sciences.

No captive programs currently exist within Cuba,but are a future component of the research-manage-ment program of the Centro Nacional de AreasProtegidas. Although a fairly large captive populationexists within the U.S., a moratorium on breeding hasbeen recommended to provide space for more critical-ly endangered taxa (American Zoo and AquariumAssociation, 1995).

Critical conservation initiatives• Establishment of an integrated research andmanagement program for Cuban iguanas withinthe national system of protected areas.• Education of local people regarding the vulner-ability of iguanas to feral dogs, cats, and pigs.• Construction of facilities for forest guards.

Priority projects1) Conduct field research and surveys to assess thepresent status of the species in the wild, analyze habi-tat requirements, and identify natural and anthro-pogenic factors influencing iguana populations.

2) Undertake natural history studies, including feed-ing ecology, social behavior, and reproduction.Results from these studies have the potential to serveas a valuable model for other, more endangered taxa.

3) Establish an in situ captive breeding program,including development of methods for artificial andseminatural egg incubation.

Contact personsAntonio PereraCentro Nacional de Areas ProtegidasCalle 18A No. 4114 e/41 y 47Miramar PlayaCiudad Habana, CubaTel/Fax: (537) 240798E-mail: [email protected]

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Amnerys GonzalezCentro Nacional de Areas ProtegidasCalle 18A No. 4114 e/41 y 47Miramar PlayaCiudad Habana, CubaTel/Fax: (537) 240798

Vincente BerovidesFacultad de BiologiaUniversidad de la HabanaCalle 25 esq. , VedadoCiudad Habana, CubaE-mail: [email protected]

Orlando GarridoMuseo Nacional de Historia NaturalCapitolio Nacional, La Habana, Cuba

Pedro PerezInstituto de Ecologia y SistemáticaAcademia de Ciencias de CubaCarretera de Varone km 3 1/2Ciudad Habana, Cuba

Allison AlbertsCenter for Reproduction of Endangered SpeciesZoological Society of San DiegoPO Box 120551San Diego, CA 92112 USATel: (619) 557-3955Fax: (619) 557-3959E-mail: [email protected]

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Fig. 5. Distribution of the Cuban iguana and protected areas that cover iguana populations.

1)2)3)4)5)6)7)8)9)10)11)12)13)14)15)16)17)18)

El Veral Nature PreserveCabo Corrientes Nature PreserveCayos de San Felipe Wildlife RefugeCayo Campos Wildlife RefugeCayo Cantiles Wildlife RefugeCayo Rosario Wildlife RefugeLas Salinas Wildlife RefugeTunas de Zaza Wildlife RefugeDelta de Cauto Wildlife RefugeDesembarco del Granma National ParkEl Retiro Nature PreserveHatibonico Wildlife RefugeBaitiquirí Nature PreserveImías Nature PreservePan de Azucar Nature PreserveTacre Nature PreservePunta Negra-Quemados Ecological PreserveCayo Caguanes National Park

Resource management areas which coveriguana populations:

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Strictly protected areas which coveriguana populations:

A)B)

C)

D)E)

Guanahacabibes Biosphere ReserveSubarchipielago de los Canarreos Multiple UseAreaSubarchipielago Jardines de la Reina MultipleUse AreaSierra Maestra Great National ParkSubarchipiélago Sabana Camagüey MultipleUse Area

Lesser Caymans iguanaCyclura nubila caymanensis

By Glenn Gerber

DescriptionLesser Caymans iguanas are very large iguanas (to1360mm total length) with pronounced sexual sizedimorphism. Maximum recorded SVL and mass ofadult males and females are 570mm and 8.5kg, and472mm and 5.2kg, respectively (G. Gerber, unpub-lished data). Mean (± SD) SVL and mass of the 10largest males and females captured on Little Caymanwere 544 ± 14mm and 7.6 ± 0.6kg, and 440 ± 18mmand 3.9 ± 0.7kg, respectively. Based on these data,adult females average 81 % of the SVL and 51 % of themass of adult males.

Coloration is also variable. Typically, adult malesare light gray with tan on the head, tail, limbs, anddorsal mid-line of the body. The dorsal crest scalesand head often have a light-blue or reddish-pink hue.Diagonal black bars partially ring the body and tail,but frequently fade with age. The chest and belly aresometimes burnt-orange or rust colored. Females areless brightly colored, lack any blue or red colorationon the head, and frequently have a greenish wash tothe entire body. Adults of both sexes have blackforefeet. Juveniles are tan or brown with 5-10 paledorsal chevrons, bordered by black, which break uplaterally to form ocelli.

Scale counts distinguishing Lesser Caymans igua-nas from other subspecies of C. nubila are given inSchwartz and Carey (1977), and recent molecularstudies (S. Davis, personal communication) haverevealed genetic differences between the subspecies.

DistributionThe Lesser Caymans iguana is native to two islands:Cayman Brac (38km2) and Little Cayman (28.5km2).The islands are 7.5km apart and are well isolated fromother land masses. Grand Cayman is 100km to theWSW, and Cuba and Jamaica are over 200km to theNE and SE, respectively. The Cayman Islands, com-posed of carbonate rock, are emergent sections of theotherwise submerged Cayman Ridge (Jones 1994).Little Cayman is low-lying with a maximum elevationof 14m, whereas Cayman Brac steadily rises from sealevel in the west to 43m in the east. The climate issub-humid tropical with distinct wet (May-November) and dry (December-April) seasons(Burton 1994a). Vegetation is similar to that whichoccurs on other limestone formations in the WestIndies (Brunt 1994). Both islands have been continu-ally inhabited since the early 1800s. Current humanpopulations for Cayman Brac and Little Cayman are

approximately 1,000 and 200, respectively.

Status of populations in the wildIn 1938, iguanas were abundant on Cayman Brac andLittle Cayman. At that time, C. Lewis (in Grant 1940)reported that iguanas "are found all over the Brac andLittle Cayman" and (in Lewis 1944) that "the coloniesof Cyclura on these two islands are reproducing, gen-erally flourishing and are in no danger of extinction."However, in contradiction to the previous statements,Lewis also reported (in Grant 1940) that "the popula-tions are rapidly being reduced by dogs, which theselizards seem unable to escape." Since that time, pop-ulations of Lesser Caymans iguanas have declinedand are clearly in danger of extinction, particularly onCayman Brac.

In 1965, Lesser Caymans iguanas were abundanton Cayman Brac only along a relatively small sectionof the southwest coastline (Carey 1966). Today, thesubspecies is nearly extinct on Cayman Brac. Overthe last four years, F. Burton (personal communica-tion) has seen only two iguanas on Cayman Brac(both juveniles) and received only two reports ofsightings (both adults; Fig. 6). Based on these results,the population probably numbers fewer than 50 indi-viduals.

Presently, Little Cayman still supports a widely,although patchily, distributed iguana population (G.Gerber, unpublished data). The population is repro-ducing and all age classes are represented, althoughjuvenile mortality is very high due to predation byferal cats. During nine months of field work on LittleCayman in 1993, over 200 iguanas were captured andmarked (Fig. 6). However, due to the inaccessibilityof much of the interior of the island and the patchydistribution of iguanas, good population estimates arenot available; mature iguanas possibly numberbetween 750 and 1,500. The population appears notto have declined significantly since the 1970s(Townson 1980, Stoddart 1980) and 1980s (Blair1983), and may even be larger today. Nonetheless,dense concentrations of iguanas which occupied themid-northern (B. Ryan, personal communication) andmid-southern (Grant 1940) coasts of Little Cayman50+ years ago no longer exist, and a growing popula-tion of feral cats and increasing human developmentseverely threaten the long-term survival of iguanas onLittle Cayman.

Ecology and natural historyLike other rock iguanas, Lesser Caymans iguanasrequire suitable forage plants, basking areas, retreats,and nesting sites. On Little Cayman, these require-ments are met in a variety of coastal and interior habi-tats, and iguanas are widely dispersed. Maximum

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densities occur in dry evergreen bushlands and thick-ets (sensu Brunt 1994) growing on exposed and high-ly weathered limestone or dolomite. These habitatsprovide a diverse assemblage of forage plants, a mosa-ic of sun and shade for thermoregulation, and an abun-dance of solution holes in the rock substrate whichiguanas of all sizes use as retreats. However, suitablenesting sites in these habitats are restricted to shallowpatches of soil that accumulate in small depressions.Consequently, many females migrate to coastal areaswith relatively deep sandy soils to nest.

The diet of all age classes consists almost entirelyof leaves, flowers, and fruits; however, iguanas occa-sionally scavenge on animal carcasses (e.g., landcrabs) or prey on slow-moving insects (e.g.,Lepidopteran larvae). Over 40 plant species havebeen identified in the diet of iguanas on Little Cayman(G. Gerber, unpublished data). Leaves of Bauhiniadivaricata, Capparis flexuosa, C. cynophallophora,Stylothanthes hamata, Ipomea pes-caprae, I. vio-lacea, and Canavalia rosea form a significant portionof the diet year-round. When available, flowers ofTabebuia heterophylla, Ipomea sp., and Canavaliarosea, and fruits of Picrodendron baccatum,Hippomane mancinella, Cordia sebestena,Myrcianthes fragrans, Guapira discolor, Coccolobauvifera, and Citharexylum fruiticosum are consumedin great quantities. However, many of these fruits aretoo large to be eaten by hatchling iguanas. Adult igua-nas (primarily female) sometimes congregate in areaswith fruiting Coccoloba uvifera or Hippomanemancinella trees.

Courtship and mating occur in April and early May,coinciding with the end of the dry season when tem-peratures and photoperiod are increasing. Mating ispolygynous and copulation takes place in male terri-tories. Males compete intensely for territories whichare occupied in all seasons. The largest males holdterritories in the best habitats and acquire the mostmatings. Male territories are large, on the order oflha, and during the breeding season as many as 10females may temporarily reside within a single terri-tory. The smallest, youngest males do not hold terri-tories and during the breeding season move from oneterritory to another attempting to court females andavoid detection by resident males. They sometimesmove several kilometers in the process and probablyacquire few copulations. Females typically occupysmaller home ranges than males, although they fre-quently leave their home range to mate or nest, andappear to be territorial only when nesting. The adultsex ratio appears to be skewed toward females.

Females lay a single clutch of 7-25 eggs (mean 15)annually, between late-May and mid-June, coincidingwith the beginning of the wet season. Mean SVL of

all reproductive females is 385mm (range 308-472).The clutch is deposited in a chamber excavated by thefemale 10-50cm below the surface. Females nesteither in small soil patches within the rocky interior orin large sandy tracts along the coast, and may migrateconsiderable distances to nest sites. After closingtheir nest, some females guard the site for periodsranging from one day to several weeks. Guardingappears to be correlated with availability of other suit-able nesting sites in the area, and thus the probabilitythat another female will attempt to nest in that loca-tion. Females that migrate to large coastal tracts ofsand to nest rarely guard, whereas females that nest insmall soil patches almost always guard.

Hatchling emergence occurs from early August toearly September and incubation averages 72 days(range 63-80). The median percentage of fertile eggsper clutch is 97.5 (range 35-100), and the median per-centage of hatchlings emerging from each nest is 91.5(range 0-100). The sex ratio of hatchlings is unity.Hatchlings average 107mm SVL (range 97-121) and50g (range 33-69). Juveniles disperse from nest sitessoon after emerging and may move long distancesbefore settling. Most juveniles marked after emer-gence from nests were never seen again, but one waslater located 5.2km away. Compared with other rockiguanas, juvenile growth is rapid, averaging approxi-mately 100mm SVL per year during the first twoyears (G. Gerber, unpublished data). The smallestfemale observed nesting was 308mm SVL and in hersecond year.

HabitatLittle Cayman contains large areas of undisturbedhabitat where Lesser Caymans iguanas are still wide-ly distributed, although much less abundant than inthe past. Many areas appearing to support prime igua-na habitat have few if any iguanas. In addition, thepace of development on Little Cayman is acceleratingand native habitats are being destroyed and fragment-ed at an unprecedented rate, especially along the coastwhere many iguanas nest. Cayman Brac, due to alarger human population, has much less undisturbedhabitat than Little Cayman and the population there isnearly extinct. On both islands, populations are farbelow carrying capacity.

ThreatsThreats to Lesser Caymans iguanas include habitatdestruction from road construction, commercial andresidential real estate development, livestock grazing(on Cayman Brac) and farming practices, predation byferal cats and domestic dogs (and possibly introducedrats), disturbance of sensitive nesting areas, and roadcasualties. Since the construction of a municipal

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power generating station on Little Cayman in theearly 1990s, habitat destruction associated with roadconstruction and real estate development haveincreased dramatically and the human population,although still small, has increased several fold. Underthe present socioeconomic conditions this pattern canbe expected to accelerate. Plans to replace the exist-ing, grass airstrip on Little Cayman with a new, pavedairstrip are underway. Proposed sites for this projectoverlap areas of prime iguana habitat on the west endof the island. Aside from the loss of habitat, such anairstrip will significantly increase human visitation tothe island and promote further development. The con-tinued destruction and disturbance of coastal nestingareas on Little Cayman is of particular concern asnesting opportunities for iguanas in the interior appearto be limited due to the paucity of suitable soil patch-es. Also, the increasing number of feral cats on LittleCayman pose an immediate threat to populationrecruitment.

Current conservation programsIguanas are protected within the Cayman Islands bythe Animals Law of 1976 (Davies 1994), but protec-tion of native habitats is lacking. The Developmentand Planning Law of 1971 provides a legal mecha-nism to prevent the destruction of terrestrial habitatsin the Cayman Islands, but has never been implement-ed (Davies 1994). Currently, the only protected areason Cayman Brac and Little Cayman are the CaymanBrac Parrot Preserve (a 65ha tract of potentiallyimportant iguana habitat) and the Little CaymanRamsar Site (an 82ha preserve encompassing BoobyPond and surrounding mangroves; Fig. 6).

The National Trust for the Cayman Islands has hadan active iguana conservation program since 1990;however, due to limited resources, efforts have large-ly concentrated on the Grand Cayman iguana. Anintensive field study of Lesser Caymans iguanas wasconducted on Little Cayman in 1993 by G. Gerber.Plans to continue this research await further funding.

A captive breeding program does not exist for thissubspecies, but may be warranted for the CaymanBrac population if it is genetically distinct from theLittle Cayman population. This possibility needs tobe investigated. No pure Lesser Caymans iguanas arepresently held in zoological institutions (B. Christie,personal communication).

Critical conservation initiatives• Acquisition and protection of terrestrial habi-tats on Little Cayman and Cayman Brac.• Development and enforcement of strict regula-tions to control domestic and feral animals.• Control of real estate development, road build-ing, and use of motor vehicles.• Increased commitment to environmental issuesamong governmental and private sectors.

Priority projects1) Eradicate or control feral cats.

2) Conduct field surveys to determine the status ofiguanas on Cayman Brac, identify more local subpop-ulations and nest areas in need of protection on LittleCayman, and obtain accurate population estimates forboth islands.

3) Carry out molecular studies to determine theamount of intra- and inter-island genetic variation.

4) Asses feasibility for construction of small supple-mental nest areas on Little Cayman. This may providea simple and cost-effective means of bolsteringrecruitment against increasing habitat losses.

5) Undertake long-term field studies on Little Caymanto quantify reproductive and other life history para-meters. Radiotelemetry will help determine whereand how far females travel to nest, dispersal patternsof hatchlings and juveniles, and movements of youngmales prior to establishing territories.

Contact personsGlenn GerberDepartment of Ecology and Evolutionary BiologyUniversity of TennesseeKnoxville, TN 37996 USATel: (423) 974-3065Fax: (423) 974-3067E-mail: [email protected]

Fred BurtonNational Trust for the Cayman IslandsPO Box 31116 SMBGrand Cayman, Cayman IslandsTel: (345) 949-0121Fax: (345) 949-7494E-mail: [email protected]

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Fig. 6. Map of the lesser Cayman Islands showing town centers (solid circles), primary roads (dotted lines),airstrips (solid rectangles), ponds (shaded), protected areas (crosshatched), iguanas sighted on Cayman Bracsince 1992 (asterisks), and numbers of iguanas marked on Little Cayman in 1993 (numbers; those aroundperimeter indicate coastal localities).

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Grand Cayman iguanaCyclura nubila lewisi

By Fred Burton

DescriptionThe Grand Cayman iguana was originally describedby Grant (1940). Although its distinction from theother two subspecies was based at that time only on itsstriking blue body coloration and caudal spinelengths, its status as a unique form has been upheld byrecent genetic studies (S. Davis, unpublished data).Minor differences in scalation, particularly in the sub-ocular region, are evident but of limited diagnosticvalue. The Grand Cayman iguana is a large form,similar in size range to the Lesser Caymans iguana,although size statistics have not been obtained fromlarge numbers of animals due to their rarity.

DistributionIguanas now survive as three or possibly four partial-ly fragmented subpopulations scattered over approxi-mately 5km2 in eastern Grand Cayman. However,reports dating from the early 1980s suggest that at thattime a small population still survived in the LowerValley and Spotts area of Grand Cayman. A localnewspaper report detailed the death of an adult in theextreme northwest of the island in the late 1940s, andMorgan (1994) found fossil remains of iguanasthroughout Grand Cayman. Taken together, thesereports suggest that the Grand Cayman iguana wasdistributed widely in dry habitats over the entire islandbefore the advent of human settlement. The presentcontraction in range to the eastern districts is probablya reflection of human activities impacting primarilythe western districts, as 78% of the island's humanpopulation lives on this half of the island.Unfortunately, the remaining iguana habitat is alsosome the best of Grand Cayman's generally poor agri-cultural land, making its protection socially and polit-ically difficult.

Status of population in the wildBased on observations made in 1938 by B. Lewis,who stated "the species is nearly extinct, and I doubtwhether more than a dozen individuals still exist onthe island. In past years they are said to have beennumerous in the interior of the east and north...Eastend people say that since 1925 the 'guanas' havebecome so scarce that is no longer worthwhile to huntthem," the population appears to have persisted in thelow hundreds over the last 70 years. The total wildpopulation is currently estimated to be no more than100 to 175 individuals (0.2 adults/ha in suitable

areas), orders of magnitude below what the habitatappears able to support (Burton and Gould, in prepa-ration). Although this taxon is strictly protected underthe Animals Law enacted in 1976, it faces increasingthreats and appears to be at high risk of extinctionover the next 20-30 years.

Ecology and natural historySimilar to other rock iguanas, the Grand Caymaniguana is almost exclusively herbivorous, occupiesrock hole retreats, and nests in inland deposits of redsoil. This subspecies is known to consume at least 45different plant species in 24 different families, with anemphasis on the Fabaceae and the Rubiaceae.Particularly important species include leaves ofRhynchosia minima, Chamaecrista nictitans, andStylosanthes hamata, whole plants of Spermacoceconfusa, and seedlings of Waltheria indica (Burtonand Gould, in preparation). All are herbaceous weedswhich thrive in disturbed, open areas. When avail-able, iguanas have also been observed to gorge them-selves on fruits of plants usually inhabiting stands ofprimary vegetation, including Picrodendron bacca-tum, Hippomane mancinella, and Myrcianthes fra-grans. Iguanas appear to exploit both primary anddisturbed habitats to obtain the variety of foods theyconsume, indicating that their present diet is probablysignificantly different from what it was prior to humanintervention.

Scat analysis conducted by F. Burton and K. Gouldrevealed that iguanas consume approximately 80%leaf material and 20% fruits. During the dry seasonwhen fruits are unavailable, leaves are consumedexclusively. Because iguanas feed mostly on theleaves of weeds and fruits falling from wild trees, itappears that their purported damage to farmer's cropshas been exaggerated. Exceptions to strict herbivoryinclude observations of iguanas feeding on fungus,crabs, and cicadas, although the latter two instanceswere more likely examples of scavenging rather thanactive predation. Coprophagy and soil ingestion havealso occasionally been observed.

Iguanas on Grand Cayman occur at such low densi-ty that it is difficult to assess the degree to which indi-vidual spacing patterns are attributable to the avail-ability of suitable retreats rather than territorial behav-ior or other factors. Whereas males show little long-term fidelity to individual retreats, females appear tooccupy small, fixed territories centered on one or twofavored retreats. The abundance of suitable refugiamay be important in controlling female distribution,while male density may be regulated primarily byintraspecific territorial interactions (Burton andGould, in preparation).

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HabitatGrand Cayman iguanas are usually observed in dryevergreen thickets and bushlands, as well as tradition-al agricultural and other man-modified habitatsderived from these vegetation communities (Burtonand Gould, in preparation). Rather than being con-fined to a single habitat type, individual iguanasappear to utilize a mosaic of natural and semi-dis-turbed habitats in response to thermoregulatoryopportunity, food, nesting substrate, predator pres-sure, and human interference.

The interaction between traditional agriculturalpractices and iguanas is complex, having both benefitsand disadvantages. Small scale clearings providegood basking spots and abundant edible herbaceousvegetation, and the mosaic of habitats resulting fromsmall scale agricultural activity likely provides agreater habitat diversity than existed previously. It ispossible that these factors to some degree balance theimpacts of exotic predators and grasses, trapping, andcattle grazing that accompany agricultural land use(Burton and Gould, in preparation).

At present, inland red earth deposits provide theonly natural nesting substrate for iguanas on GrandCayman. These deposits are essentially restricted todry evergreen thickets, dry evergreen bushlands, andthe agricultural lands derived from these formations.Nesting attempts have not been observed in soil areasconverted to grasslands.

ThreatsAll sites where iguanas are known to occur are subjectto human-related threats, including predation by wildand domestic cats and dogs, conversion of land to cat-tle grazing or intensive farming, habitat destructionfor real estate development, road casualties, and trap-ping or shooting by farmers who perceive iguanas asa threat to their crops. In particular, the intensity oflarge scale deforestation and new road constructionhas increased enormously in the eastern districts overthe last decade, and under present socioeconomicconditions this trend is expected to accelerate.

Current conservation programsAn integrated conservation program for the GrandCayman iguana is being implemented by the NationalTrust for the Cayman Islands. This project incorpo-rates research, habitat protection, captive breeding,reintroduction/restocking, and conservation educa-tion. Iguanas feature prominently in the annualNational Trust Fair, where 2,000 to 3,000 school chil-dren have the opportunity to learn about this and otherendangered species. The ultimate goal of the Trust'siguana program is to secure and protect a stable,breeding wild population capable of surviving indefi-

nitely without ongoing human intervention. In addi-tion to the direct goal of preventing the extinction ofthe iguana, the Trust views this program as a flagshipspecies approach to its more fundamental mission ofprotecting the unique natural environments of theCayman Islands.

To help insure a future for the Grand Cayman igua-na in the wild, a nature reserve plan for eastern GrandCayman is in the early stages of development. Todate, the National Trust has acquired conservationland through grants of Government land, throughdonations by U.S. citizens owning land in the CaymanIslands, and by direct purchase using funds raised bypopular appeals. At present, the most promising pos-sibility for future introductions appears to be theSalina Reserve in the northeastern part of the island, a253ha area which contains a small but viable amountof iguana habitat (approximately 2ha). Althoughthere is currently no evidence of wild iguanas in thisarea, trial translocations indicate that it may be suit-able for supporting a limited number of iguanas. Thearea has subsequently been mapped, its vegetationcatalogued, and a low-impact trail network estab-lished. The Queen Elizabeth II Botanic Park, a 26haproperty jointly managed by the National Trust andthe government, has also shown considerable poten-tial as iguana habitat, and is a strong candidate forrestocking efforts.

Field research designed to elucidate the status andecology of Grand Cayman iguanas in the wild hasbeen underway since 1991 in collaboration with theFriends of the National Zoo (Washington, D.C.).Work to date includes assessment of the diet of wildand released captive iguanas, acclimatization to thewild and territorial interactions among released cap-tives, population distribution and habitat utilization,and limited studies of nesting behavior.

A captive breeding program was initiated at theNational Trust in 1990. The original breeding stockconsisted of animals already in captivity on GrandCayman, animals donated to the National Trust by theLife Fellowship Sanctuary (Seffner, Florida), and afew wild hatchlings which had roamed into developedareas with traffic and feral predators. As a result ofgenetic studies undertaken by S. Davis, animals bredin 1990 and 1991 from Life Fellowship were subse-quently found to have hybrid ancestry involvingLesser Caymans iguanas, C. nubila caymanensis.These animals were surgically sterilized to excludethem permanently from the breeding program.Additional analysis of captive Grand Cayman iguanasin both the Cayman Islands and U.S. captive collec-tions has shown that genetic variation is low by com-parison with Jamaican iguanas and Lesser Caymansiguanas from Little Cayman.

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The in situ captive program is intended to functionas an integral part of conservation efforts in the wild,and includes release of captive-bred iguanas into pro-tected areas. Sterilized hybrids outfitted with radio-transmitters have proven to be an important means forevaluating release protocols for iguanas into variouscandidate habitats. By tracking and studying releasedhybrids, a small area within the Trust's existing SalinaReserve capable of supporting at least one breedingfemale has been identified. These studies have alsoverified the ability of captive born and reared iguanasto adapt naturally, without pre-release conditioning, tolife in the wild. On the basis of these studies, a pair ofgenetically pure adults was released into the area in1994.

With funding from the Zoological Society ofMilwaukee County and the Foundation for WildlifeConservation, the National Trust recently constructeda new captive facility where iguanas can be bred andreared for eventual release back into their native habi-tat. The facility will house up to 12 adults and 32juveniles.

Critical conservation initiatives• Establishment of sufficiently large protectedand managed areas remote from habitation,where exotic predators and adverse human inter-ference can be effectively controlled and a largebreeding population restored.• Implementation of program for farmers to dis-courage iguana trapping, shooting, and the prac-tice of allowing domestic dogs and cats to roamfreely in areas where iguanas are known to occur.

Priority projects1) Enhance habitat at the Queen Elizabeth II BotanicPark.

2) Institute feral predator control, particularly for catsin remote agricultural areas of eastern GrandCayman.

3) Conduct field research and monitoring of the wildpopulation.

4) Produce an educational poster for Grand Caymaniguanas and red-footed boobies.

5) Acquire habitat, particularly agricultural land thatcould support iguanas and thickets with potential nat-ural iguana habitat adjacent to the Salina Reserve andthe Queen Elizabeth II Botanic Park.

Contact personsFred BurtonNational Trust for the Cayman IslandsPO Box 31116 SMBGrand Cayman, Cayman IslandsTel: (345) 949-0121Fax: (345) 949-7494E-mail: [email protected]

Richard HudsonDepartment of HerpetologyFort Worth Zoo1989 Colonial ParkwayFort Worth, TX 76110 USATel: (871) 817-7431Fax: (871) 817-5637E-mail: [email protected]

Anegada Island iguanaCyclura pinguis

By Numi Mitchell

DescriptionThe Anegada Island iguana is a relatively large, stoutmember of its genus. Males have been recorded withSVL reaching 560mm and may grow larger. Juvenilesare faintly or boldly patterned with wide gray to mossgreen bands interspersed with wide gray to black ante-riorly directed chevrons. The bands fade and are gen-erally lost as the animals mature. Adults are grayishor brownish-black dorsally with varying amounts ofturquoise on the dorsal spines, tail base, fore and hindlegs. Occasionally the bluish coloration extends uponto the sides of the individual, particularly in males.Females tend to be relatively dull in color, exhibitingless brilliant blue if any. Ventral coloration of juve-niles and adults varies from a solid buffy white to lightgray. Sclera of eyes are dull yellow when animals arecalm, but flush pink to red with increasing levels ofagitation.

DistributionThe common name of the Anegada Island iguana ismisleading, as the animal was once distributed overthe entire Puerto Rico Bank. Fossils are known fromSaint Thomas and Puerto Rico. The iguanas werelikely extirpated when localities became densely set-tled by humans. Vulnerability to predation by humansand their dogs and cats may have resulted in a con-traction of its distribution to Anegada. The numerousescape holes coupled with a large expanse of undevel-oped land supporting few non-native predators may

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have allowed the iguana population to persist there.The distribution of iguanas on Anegada today is close-ly tied to porous limestone habitats.

Status of populations in the wildPopulation density in 1968 was estimated at 2.03/ha(Carey 1975). In 1991, this figure had dropped to0.36/ha in comparable habitat. Extrapolation of den-sity estimates, distribution, and relative habitat quali-ty yields a population estimate for Anegada of 164individuals (Mitchell, in review). A small restoredpopulation also exists on Guana Island with eightfounding adults (Goodyear and Lazell 1994), fromwhich three juveniles have been translocated toNecker Island. The total population, including indi-viduals on Anegada, Guana, and Necker, probablyconsists of fewer than 200 individuals.

Ecology and natural historyEstimates in the late 1960s (Carey, 1975), madebefore the introduction of domestic livestock, showedsmall home ranges for both sexes (<0.1 ha), one prin-cipal burrow per animal, a 1:1 sex ratio, and habitsthat indicated monogamy (apparent pairs inhabitedseparate but proximate burrows in a joint home rangeisolated from other pairs). The current populationstructure is quite different. While previous studiesmay not have been sensitive to long range movements,it now appears that home ranges are quite large onAnegada: males average 6.6ha (range 2.2-12.3) andfemales average 4.2ha (range 2.8-5.6). Home rangesbroadly overlap and have one or two centers of activ-ity. For males, activity centers may be associated withhome ranges of females; one male may have two cen-ters almost a kilometer apart. In 1991, the sex ratiohad dropped to 1 female:2 males. Thus male compe-tition for limited females may be responsible for thehigh degree of home range overlap.

Burrows of both sexes may be located on the oldlimestone reef-tract or in sandy areas adjacent to it. Ifavailable, iguanas will use additional holes or crevicesas emergency retreats. Female centers of activity areusually associated with one or several principal bur-rows. Whereas degraded vegetation may provide formale subsistence, it may not provide females with suf-ficient energy to allow them both to produce eggs andcompete with other animals for forage to support theirown growth and metabolism. Reproducing females mayhave low survivorship, resulting in the present skewedsex ratio. Females usually lay one clutch of about 12-16 eggs per year in late spring or early summer.

Although largely facultative herbivores, all age-groups of these iguanas are opportunistic carnivores.Invertebrates (beetles, caterpillars, centipedes, roach-

es) form <1% of the natural diet, although this may bea result of limited availability. The bulk of the dietconsists of leaves and fruits.

HabitatOver the past 20 years, since domestic livestock werereleased to breed freely island-wide, grazing pressureby goats, sheep, burros, and cattle has radicallychanged the vegetational composition of Anegada.Not surprisingly, the diet of the iguana is now com-posed of plant species the feral animals reject. Almost30% of the iguanas' diet consists of a plant containingsecondary compounds (Croton discolor) apparentlytoxic to ungulates. Over 55% of the diet is composedof fruits (Byrsonima, Coccoloba, Eleaodendron,Eugenia) that the livestock ignore.

ThreatsAreas on Anegada that once contained dense popula-tions of iguanas now support few or none. Researchindicates that this is due to three major causes, includ-ing competitive grazing pressure from free-ranginglivestock, predation by feral dogs, and predation ofjuveniles by feral cats.

Current conservation programsA major grant has been received from theEnvironment, Science, and Energy Department of theUK Foreign and Commonwealth Office to facilitateconservation activities on Anegada. Goals of this pro-gram are to 1) implement a cat eradication/controlfeasibility study, 2) expand the current headstart facil-ity, 3) train Senior Terrestrial Warden Rondel Smith iniguana husbandry and facility maintenance, 4) con-duct population censusing and mapping at nestingsites and other potential sites where adults may befound, and 5) develop environmental education mate-rials to raise public awareness of the importance andvulnerability of iguanas on Anegada.

In the 1980s, eight iguanas were moved fromAnegada to Guana Island, British Virgin Islands, tostart a second population in part of the species' formerrange (Goodyear and Lazell 1994). This is not a lime-stone island, and does not provide as many naturalretreats as Anegada. In the absence of introducedpredators, however, the iguanas appear to do well andreproduce in areas that are free of sheep (the only feralgrazing competitor present). Currently, approximate-ly 20 adult iguanas are estimated to inhabit Guana.Offspring have been seen each year since 1987, butrecruitment is very low over much of the island.Guana Island Wildlife Sanctuary continues to try torid the island of sheep, which may improve the habi-tat for iguanas.

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Critical conservation initiatives• Creation of a national park to protect iguanason Anegada, and maintenance of a reservoir ofbreeding animals on Guana whose offspring maybe used to restock depleted areas on Anegada.Although a national park has been approved inconcept by the Anegada Lands Committee, landtitle issues must be resolved before this projectcan move forward.• Livestock purchase and removal from designat-ed protected areas, including Guana Island.

Priority projects1) Construct livestock exclosure fences around desig-nated protected areas.

2) Assess status and density assessment of iguanasthroughout Anegada.

3) Examine the physiology of the declining femalepopulation.

4) Conduct vegetation recovery experiments to assesspotential for restoration.

5) Expand the headstarting program on Anegada toproduce hatchlings for release into restored areas.

6) Carry out genetic studies on both Anegada andGuana Islands.

7) Organize a PHVA workshop to raise local, national,and international awareness.

Contact personsNumi MitchellThe Conservation AgencyBranch Office, 67 Howland Avenue

Jamestown, RI 02835 USATel: (401) 423-0866Fax: (401) 423-0199E-mail: [email protected]

James LazellThe Conservation Agency6 Swinburne StreetJamestown, RI 02835 USATel: (401) 423-2652Fax: (401) 423-2396E-mail: [email protected]

Joseph Smith AbbottNational Parks TrustMinistry of Natural ResourcesBox 860, Road Town, TortolaBritish Virgin IslandsTel: (284) 494-3904Fax: (284)494-6383E-mail: [email protected]

Glenn GerberDepartment of Ecology and Evolutionary BiologyUniversity of TennesseeKnoxville, TN 37996 USATel: (423) 974-3065Fax: (423) 974-3067E-mail: [email protected]

Richard HudsonDepartment of HerpetologyFort Worth Zoo1989 Colonial ParkwayFort Worth, TX 76110 USATel: (871) 817-7431Fax: (871) 817-5637Email: [email protected]

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Fig. 7. Distribution of iguana habitat on Anegada Island. Historical (1930-1979, left of arrow) and present den-sities (1980-1993, right of arrow) of Cyclura pinguis on Anegada. In locations showing single estimates (thosewithout arrows) densities have not changed. H=high, M=medium, L=low, O=occasional individuals, N=no indi-viduals, a=adults, j=juveniles, b=both.The 12.5-ha study area in which animals were captured, marked, andreleased by Mitchell (1999) is shown.

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Ricord's iguanaCyclura ricordi

By Jose Ottenwalder

DescriptionRicord's iguana is a large (SVL to 495mm in males,430mm in females) iguana that can be readily distin-guished by greatly enlarged and spinose scales at eachcaudal verticil in both adults and juveniles. Color pat-terns show little individual or ontogenetic variation,consisting of five to six bold pale gray chevrons alter-nating with dark gray to black chevrons, of which fivecontinue as bold but narrow lines diagonally onto theventer. In adults, the dark chevrons are less contrast-ing than in juveniles.

DistributionRicord's iguana is known only from southwesternDominican Republic, where it is restricted to the aridValle de Neiba and the most xeric portion of thePeninsula de Barahona coastal lowlands (Fig. 8). Thetwo populations are separated by the mesic Sierra deBahoruco (Massif de la Selle in Haiti), with threepeaks exceeding 2000m that form an extensive eco-logical barrier. Past drier Pleistocene climates mayhave allowed genetic exchange between the two sub-populations. Throughout their range, Ricord's igua-nas are sympatric with rhinoceros iguanas.

The Neiba Valley population includes Isla Cabritos,a 12 by 2km island in Lago Enriquillo, a hypersalinelake that undergoes extreme reductions every 15-30years due to severe droughts and high evapotranspira-tion. In the past, this has caused the island to becomeconnected with the southwestern lakeshore, producinga peninsular effect and allowing two-way populationexchange of Ricord's iguana and rhinoceros iguanasinhabiting the lake periphery. Return to previousinsular conditions occurs during years of unusuallyheavy rainfall. The 1979-1980 cyclic episode result-ed in lake levels rising more than 3m. Following atwo-year period of increased drought and reducedrainfall, as of March, 1997, Isla Cabritos againbecame connected with the mainland, at the south-western portion of the lake's shoreline near Jimani. J.Ottenwalder suspects that one-way migration fromIsla Cabritos to the lake's south shore allows for dis-persal between cyclic peninsular events. Over-waterdispersal of iguanas could be aided by water surfacecurrents generated by strong daily winds from NeibaBay through the Neiba Valley, together with increasedbuoyancy provided by hypersaline water. BothRicord's iguanas and rhinoceros iguanas will float andswim in fresh water (J. Ottenwalder, personal obser-vation).

In the Barahona Peninsula range, the distribution ofRicord's iguana has yet to be accurately established.Areas of occupancy include lowlands to the north,northeast, and east of the Cabo Rojo region, below thelower foothills of Sierra de Bahoruco, and on thewestern side of the Parque Nacional Jaragua. The old-est known occurrence inside the park is the north-western corner at Tru Nicola, although the preciseextent to which the species distribution continues eastand south is insufficiently known. However, parkwardens have recently observed Ricord's iguanas inthe eastern and southwestern portions of the park,including the Oviedo Lagoon, where the speciesinhabits limestone areas of the shoreline and severalsmall cays inside the lagoon.

The presence of Ricord's iguanas in the Haitianextension of the Neiba Valley plain has been pre-sumed (Schwartz and Carey 1977). However, thespecies has never been recorded from the Lake EtangSaumatre basin or the dry coastal fringe extendingfrom Anse-a-Pitres to Marigot across the Dominicanborder at Pedernales.

Status of populations in the wildAll available data indicate that the historical range ofRicord's iguana was small and disjunct. Several fac-tors indicate that the population is currently declining,including direct observation, reduction in the extentand quality of available habitat, and documentation ofthe negative effects of introduced species. Research-ers and local inhabitants agree that until the mid-1970s, population densities of mature individualswere much higher than they are at present. Lackingmore accurate data, a current population estimate of2,000 to 4,000 is probably conservative but fair.

Ecology and natural historyCompared to rhinoceros iguanas, Ricord's iguanas arequite specialized. Several key environmental factors,including soil depth and texture, landform, bedrockparental material, and climate seem to determine theirpresence. Ricord's iguanas inhabit the most aridregions of the Dominican Republic, where the climateis highly seasonal. Representative localities includeDuverge (annual rainfall 470.6[178.4-812.8]mm, 46.6days/year; 28.8[23.1-33.0]°C) and Pedernales (annualrainfall 633.3[160.2-1922.8]mm, 34.7 days/year;27.9[21.5-34.1]°C). Annual precipitation is distrib-uted in two rainy periods, May-June and September-October, while December-March is exceedingly dry.

Ricord's iguanas are strongly associated with thornscrub woodlands, particularly with the thorn scrub-dry forest ecotone. Typical habitat can be found northof Cabo Rojo inside the fork of the Oviedo-Pedernalesand Cabo Rojo-Acetillar bauxite mine roads. The

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topography of the area consists of a series of broad,flat plains punctuated by rocky steps and marine ter-races with very fine soil over exposed dogtooth lime-stone. The plant community is disturbed and not verydiverse, consisting of only about 35 species of tra-cheophytes (18% endemic) (Fisher-Meerow 1983;Fisher-Meerow and Judd 1989). Members of theCactaceae, Fabaceae, and Euphorbiaceae are com-mon. A single species, Acacia macracantha, com-prises 50% of the cover. Other common trees areCapparis ferruginea, Guaiacum offtcinale, Haitiellaekmanii, Metopium brownei, Opuntia moniliformis,and Phyllostylon brasiliense. Common shrubsinclude Croton origanifolius, Croton discolor, andLipia alba. Among the succulents, Agave brevipetala,Cephalocereus polygonus, Harrisia nashii,Melocactus communis, Cylindropuntia caribea, andOpuntia dillenii predominate. Trees and shrubs arewidely spaced, without forming a closed canopy.Further north, only rhinoceros iguanas are present at asecond, higher elevation site, with similar temperaturebut greater rainfall. This area consists of a marginalsubtropical dry forest community on eroded dogtoothlimestone and gently sloping terrain with occasionalstep cliffs and terraces. Here, plant diversity is high-er (45 species, 9% endemic), and Malvaceae,Euphorbiaceae, and Fabaceae are the most abundantfamilies in number of species and individuals.Capparis ferruginea, Zizyphus rignoni, Camerariaangustifolia, Cordia buchii, and Plumeria obtusa arecommon, although some species are restricted tolimestone outcrops. Shrubs include Abutilon abu-tiloides, Comocladia dodonea, Croton ciliato-glan-dulifera, Cryptorhyza haitiensis, Guaiacum sanctum,Hybanthus havanensis, Lantana camara, and Turneradiffusa. Vines are very common, as is the herbCallisia repens. Plants with spines are nearly absentfrom less disturbed areas, while vegetation approach-es thorn woodland in the most disturbed areas. Theseare generally dominated by open-canopy legumes,including Acacia macracantha, Prosopis juliflora,and Senna atomaria. Acacia-dominated areas proba-bly represent secondary reductions of more diversepast communities. In the the transition zone betweenthese two sites, both iguana species are present, shar-ing the more diverse edge habitat.

On Cabritos Island, where Ricord's iguanas havehistorically outnumbered rhinoceros iguanas based onfrequency of sightings by visiting researchers, theplant community is a succulent-dominated 5-6m dryforest on white sandy soil with low topography.Ricord's iguanas occur on north and south gentleslopes as well as on the central plateau, where soilconditions are favorable for their extensive burrows.

Among other shrubs, Cylindropuntia caribea is com-mon. On the south mainland shores, Ricord's iguanasoutnumber rhinoceros iguanas by a factor of nine inthe flatlands surrounding Laguna del Medio near ElLimon, considered the driest area in the country. Thesoil is very fine, porous, and from dark to whitish graycolor, without rock exposure. Savanna vegetationcover is about 25%, dominated by Jacquinia (twospecies), Piscidia ekmanii, Maytenus buxifolia, andthe less common Prosopis juliflora; shrubs includeMimosa sp., Pictelia spinifolia, Crossopetalum decus-satum, Turnera diffusa, Croton discolor, Malpighiasp., and Lantana decussatum; grasses includePortulaca sp., Evolvulus sericeus, Stylosanthes hama-ta, and members of Poaceae (DVS/SEA 1990).Ricord's iguanas feed on a wide variety of plants andplant parts, depending on local availability, includingConsolea, Opuntia, Croton, Prosopis, Melocactus,Cordia, and Guaiacum. Insects and crustaceans arealso taken opportunistically.

Seemingly optimal habitats are characterized byalluvial powdery-clay soils bordered by marine sedi-ments and low forested hills with high plant diversity.Flat topography, low precipitation, and local soil con-ditions (e.g. fine texture, slow permeability, low flood-ing risk, good drainage) allow for low erosion ratesand maximum soil stability. While rhinoceros iguanasmake extensive use of limestone crevices in additionto soil burrows, Ricord's iguanas prefer to dig soilburrows which they continue to expand over time.Hollow tree trunks and rock cavities are also used forretreats when soil is unavailable. Retreat entrancesare generally dug under dense thorny vegetation,shrubs, stumps, or exposed rocks.

Nesting sites are separate from retreats, in finesandy soils. Egg laying is highly synchronized withthe first rainy period (May-June). Females lay 2-18eggs per clutch (mean 11.1 ± 4.2). Egg chamberdepth is about 40cm, with a stable temperature of 30-31°C. Incubation lasts 95-100 days, and hatching issynchronized with the second rainy season(September-October). Average SVL and mass ofhatchlings is 87.4mm and 30g. Females reach sexualmaturity at about 2-3 years of age. In captivity, firsttime clutches are usually very small (2-4) and ofteninfertile. The social behavior of Ricord's iguana gen-erally resembles that of other rock iguanas, althoughwild males defend females much more aggressively incaptivity than do wild male rhinoceros iguanas main-tained at lower densities in comparable enclosures.Although of major research interest and significantconservation importance, little is known of interspe-cific interactions between Ricord's and rhinocerosiguanas.

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HabitatThe total range of Ricord's iguana in the DominicanRepublic is under 100km2, and less than 60% of thehistorical range is occupied, most of it showing vari-ous levels of disturbance. Suitable habitat has beenseverely reduced by clearing, fragmentation, andtransformation, including some of the oldest and bestknown iguana sites. The area along the south shore ofLake Enriquillo between Du vergé-Las Baitoas and ElLimon has suffered considerable habitat loss as aresult of agricultural development, free-ranging live-stock, charcoal production, fuelwood extraction, anddrainage of a lagoon and small seasonal wetlands.The Isla Cabritos range, which used to be intensivelyexploited for hardwood cutting, charcoal, and live-stock grazing (up to 500 goats, 200 burros, and somecattle), has experienced extensive natural regenerationduring the past 15 years. Since 1992, protective manage-ment has improved, and present conditions are stable.

The distribution of Ricord's iguana in the BarahonaPeninsula range is insufficiently known due to theimpenetrable, dense nature of the vast dry forest thatextents inside Parque Nacional Jaragua. Confirmedareas of occurrence include relatively small patches oflowland thorn scrub and thorn scrub-dry forest eco-tone in the Cabo Rojo region north of the Oviedo-Pedernales road, lowlands 150m to the north andnortheast of Cabo Rojo at the base of lower foothillsof Sierra de Bahoruco, and on the western side of thepark. Inside the park boundaries, Ricord's iguanas arebest documented from the northwestern corner andfrom the Oviedo Lagoon area. As penetration of theforest along this section is extremely difficult due tothick thorny forest and uneven dogtooth limestone ter-rain, the extent to which the species range continues tothe east and south is still uncertain. Outside the park,iguana habitats are being reduced by conversion tofarmlands, limestone mining, charcoal production,fuelwood collection, hardwoods extraction, and graz-ing livestock. Habitat protection inside the park hasimproved, although similar human impacts on forestcommunities supporting iguanas still occur inside andalong buffer zones areas.

ThreatsThe major threats to Ricord's iguanas are from humanactivities resulting in habitat reduction and degrada-tion (clearing of vegetation for agricultural use, char-coal production, harvesting of fuelwood and hard-woods, overbrowsing by free-ranging livestock, min-ing of limestone, illegal collection of live cacti forlocal and international trade), in combination withlocal subsistence hunting for food and predation fromintroduced carnivores (dogs, cats, and mongooses).Competition from mammalian herbivores probably

also occurs. Hunting of Ricord's iguanas for food andtrade has increased gradually since the mid 1970s,both for local consumption as well as at a few orientalrestaurants in Santo Domingo where iguanas wereoffered as a specialty dish. In the past, some huntersused to set up to 100 snare traps per day at theentrance of retreats, with 30-50% trapping success.Although current populations no longer support thenumbers harvested 15 years ago, iguanas continue tobe captured opportunistically in all areas with remain-ing populations, except on Isla Cabritos where lawenforcement is presently effective.

Current conservation programsAside from occasional smuggling of animals acrossthe Haitian border, compliance with internationalCITES trade regulations is effective. Enforcement ofnational protective legislation in the DominicanRepublic has improved during the past few years, buteffective control is adversely influenced by a numberof factors. Clearing of natural habitat for develop-ment is not being prevented nor regulated and illegalhunting for food and the local pet market continues.

Ricord's iguana is partially protected in two areas.In the Neiba Valley, about 60% of the area supportingiguanas, including Isla Cabritos and a section of thesouth shore of Lake Enriquillo, is protected within therecently created Lago Enriquillo National Park. TheIsla Cabritos population has been protected within IslaCabritos National Park since 1974.

In the Barahona Peninsula range, two protectedareas, Parque Nacional Jaragua and the AcetillarScenic Reserve, cover most of the remaining distribu-tion of the species to the north and east of Cabo Rojo.Ricord's iguanas are only known from the park'swestern boundary, where conflicts with limestonemining concessions on both sides of the park bordercontinue to be unresolved. Until now, no formal man-agement has been established in the Acetillar reserve,and the habitat is impacted by a variety of activities.

As of November, 1995, the total captive populationof Ricord's iguana was 5.9 individuals in two collec-tions (Indianapolis Zoo and one private collection; B.Christie, personal communication). Successful cap-tive breeding has been achieved in both, but survivor-ship of young has been low (J. Ottenwalder and B.Christie, unpublished data). The only other signifi-cant captive breeding program was developed at theParque Zoologico Nacional (ZooDom). Althoughadversely affected by institutional problems, the pro-gram lasted for a number of years with comparablesuccess. There are plans to re-establish new breedingcolonies at both ZooDom and the Indianapolis Zoo, aspart of a collaborative program between the two insti-tutions. ZooDom recently completed a breeding

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exhibit to house a founder group once ongoing popu-lation surveys indicate it is safe to remove animalsfrom the wild.

Critical conservation initiatives• Effective enforcement of current regulationsprotecting populations.• Strengthening of current regulations and legis-lation protecting iguana populations by increas-ing fines and designating selected areas as criti-cal habitat whether outside or inside existingprotected area boundaries.• Development of educational awareness cam-paigns to promote iguana conservation, particu-larly to discourage subsistence hunting of igua-nas for food and local trade, and habitat conver-sion for charcoal production.• Development of a national conservation andrecovery strategy and working group to includegovernment agencies, non-governmental conser-vation organizations, and iguana researchers.• Establishment of research, management, andmonitoring programs for wild populations andcritical habitats.• Involvement of local organizations and com-munities in any iguana conservation, education,and research activities.

Priority projects1) Conduct status surveys of the Parque NacionalJaragua-Cabo Rojo and Lake Enriquillo iguana popu-lations.

2) Carry out field studies on natural history and ecol-ogy, and assessments of population trends and threatsin order to develop a recovery strategy.

3) Immediately eradicate cats from Isla Cabritos.

4) Establish local and national educational programs

in order to reduce current causes of mortality, raiseawareness concerning threatened status, and promotesupport for proposals to expand boundaries of existingprotected areas.

5) Re-establish a captive breeding and research pro-gram at ZooDom, while continuing to strengthen theongoing program at the Indianapolis Zoo.

Contact personsJose OttenwalderUNDP/GEF Dominican Republic Biodiversity ProjectUnited Nations Development ProgramPO Box 1424, Mirador SurSanto Domingo, Dominican RepublicTel: (809) 534-1134Fax: (809) 530-5094E-mail: [email protected]

Bill ChristieIndianapolis Zoo1200 W. Washington StreetIndianapolis, IN 46222 USATel: (317) 630-5172Fax: (317) 630-5153E-mail: [email protected]

Sixto Inchaustegui and Ivon AriasGrupo Jaragua Inc.El Vergel 33Santo Dominigo, Dominican RepublicTel: (809) 472-1036Fax: (809) 412-1667E-mail: [email protected]

Departamento de Vida SilvestreSubsecretaria de Rescursos NaturalesSecretaria de Estado de AgriculturaSanto Domingo, Dominican Republic

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Fig. 8. Present distribution of Ricord's iguana in the Dominican Republic. The solid circles represent the cur-rent known distribution. The open circles indicate areas where the presence of populations is suspected butcurrently uncertain and in need of confirmation.

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San Salvador iguanaCyclura rileyi rileyi

By William Hayes

DescriptionSchwartz and Carey (1977) concluded that the SanSalvador iguana is the largest subspecies of C. rileyi,with a maximum size of 307mm SVL. More recentstudies (Hayes et al., unpublished) indicate that manyindividuals of the San Salvador iguana on Low Cay, asatellite of San Salvador Island, exceed 350mm SVL,and attain a size of up to 395mm SVL (890mm totallength). Although iguanas on Guana Cay within SanSalvador's Great Lake also average over 300mm SVL,those on other cays rarely do.

The species is characterized by the absence of azy-gous scales in the prefrontal suture, rostral scalealways in contact with nasals, first prefrontal never incontact with precanthal, dorsal crest scales on theneck always higher than on the body, body crest scalesalmost never higher than postsacral crest scales, and avariety of other scale-count features (Schwartz andCarey 1977). Characters that distinguish SanSalvador iguanas from the other two subspeciesinclude several features of facial scalation and poorlydefined postsacral crest scales.

Dorsal coloration of San Salvador iguanas is strik-ing but variable. Dorsum colors of red, orange, yel-low, green, or brown are usually punctuated by darkermarkings and fine vermiculations. Males generallyexhibit more color (red, orange, or yellow) and con-trast than females, especially at warmer body temper-atures. Juveniles are solid brown or gray, often with aslightly paler middorsal band having faint longitudi-nal stripes or indistinct darker areas near the middor-sal crest. Juveniles lack the brighter coloration andvermiculations of adults, as well as the dorsalchevrons or pale diagonal markings present on juve-niles of other taxa.

DistributionFossil remains found by Olson et al. (1990) indicatethat San Salvador iguanas once occurred throughoutthe island of San Salvador (area 150km2). Today,however, sightings on the mainland are exceedinglyrare, occurring most often on the eastern side betweenGreat Lake and Storrs Lake. Although the LucayanIndians may have hunted iguanas in earlier centuries,the extensive agricultural practices and other humanactivities of the last 100 years likely represent thegreatest contribution to the iguana's demise. At pre-sent, San Salvador iguanas appear to be restrictedlargely to five tiny offshore cays (Gaulin, Goulding,Green, Low, Manhead) and two cays within Great

Lake (Guana and Pigeon; Hayes et al. 1995). Theywere presumably extirpated on at least six additionalcays, with two extinctions occurring in recent decades(discounting an unconfirmed sighting on High Cay in1991). The seven inhabited cays range in size from 1-12ha and total approximately 26ha of marginal toexcellent habitat.

Status of populations in the wildRecent censuses by Hayes et al. (1995) suggested thatapproximately 500-600 individuals remain. However,they suspected that juveniles were underestimated intheir surveys, and have since learned that a moderatepopulation thrives on Pigeon Cay, the one known pop-ulation they had not yet visited. Nevertheless, thissubspecies likely numbers fewer than 1,000.Populations on the isolated cays vary from perhaps asfew as 10 (Gaulin Cay) to as many as 250 (GreenCay). Several populations are threatened by human-related causes and appear to be declining.

Ecology and natural historyThe habitat on cays presently occupied by iguanasvaries greatly. Vegetation on offshore cays is similarin varying degrees to coastal rock, sand strand and seaoat, and coastal coppice plant communities describedon the mainland (Smith 1993). However, for cayswithin inland lakes, the vegetation resembles theblacklands coppice (Guana Cay) and mangrove(Pigeon Cay) communities on the mainland. Habitatson the mainland of San Salvador are highly diversifiedand suitable enough to harbor large iguana popula-tions, but feral animals are numerous in many areas.

The number of plant species on each cay variesfrom ten on Green and Gaulin Cays to more than 40on Guana and Low Cays (Moyroud and Ehrig 1994;Hayes et al., unpublished data). Mean and maximumbody sizes of iguanas vary significantly from cay tocay, and are positively correlated with plant diversity,suggesting nutritional constraints on body size (W.Hayes et al., unpublished data). Iguanas are largest onLow Cay and smallest on Manhead Cay. Previouslyreported measurements of body size (Schwartz andCarey 1977) were limited to samples from cays hav-ing low plant diversity. Thus, prior recognition of C.rileyi as the smallest of the rock iguanas may be anartifact of historical extinctions resulting in extantpopulations being confined today largely to the mostinaccessible cays having minimal plant diversity.

Iguanas are locally most common in the vicinity oflimestone rock outcrops and/or patches of sea grape(Coccoloba uvifera). On some cays they are numer-ous in patches of buttonwood (Conocarpus erectus)where they ascend into the foliage to browse. OnPigeon Cay they are frequently encountered basking

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on the limbs of mangrove trees, often several metersor more above the ground. The iguanas share theirhabitat with nesting seabirds on several cays, mostnotably on Gaulin Cay where brown noddies (Anousstolidus) and sooty terns (Sterna fuscata) are extreme-ly dense (100+ nests/ha).

Aspects of feeding and reproductive ecologyremain unstudied but are likely similar to other rockiguana species. Adult males appear to be territorialthroughout the year. As in other Bahamian taxa,courtship and mating probably occur in May, followedby nesting and egg-laying in June or July.Copulations have been observed by investigators vis-iting the cays during the last week of May (W. Hayes,unpublished data). Stejneger (1903) reported a clutchthat numbered five eggs. Hatchlings probably emergefrom nest burrows in September or October. Likeother rock iguanas, San Salvador iguanas presumablyrequire sandy areas for nest construction. Such habi-tat appears to be limited on Guana Cay, but the pres-ence of several juveniles in 1994 is indicative of suc-cessful nesting there.

HabitatOn most cays, iguanas range widely throughout allavailable habitats. However, on Low Cay iguanas arelargely restricted to areas of sea grape that comprise arelatively small portion of the island. Although a man-made structure is under construction on High Caywhere iguanas are thought to be extirpated, none ofthe other cays are inhabited and, at present, are sel-dom visited. On several cays where iguanas have dis-appeared the habitat appears suitable for reintroduc-tion; however, these cays may harbor feral rats thatcould be incompatible with reintroduction effortsunless they are first extirpated.

Considerable habitat has been lost on the mainisland of San Salvador. Nevertheless, extensive areasof excellent but very remote habitat remain whichcould support large populations of iguanas if develop-ment on the island could be halted (which appearsunlikely). Thus, while habitat availability does notpresently limit the mainland population, it may wellhinder the prospect of increasing the total populationsize via future reintroductions.

ThreatsAlthough remote and relatively difficult to access,populations on the cays are still threatened by human-related causes (Hayes et al. 1995). All size classes ofiguanas are readily seen on Goulding, Green,Manhead and Pigeon Cays, which suggest the pres-ence of healthy, stable populations. However, juve-niles are conspicuously scarce on Guana and LowCays, and possibly absent on Gaulin Cay. The scarci-

ty of juveniles on Low Cay is probably attributable tothe presence of feral rats only recently detected there(Hayes et al. 1995). The iguana population consistsalmost entirely of large, aged adults. More recently,rats have also been seen on Guana, High, and PigeonCays. Considering the apparent impact of rats oninsular populations of the tuatara (Sphenodon puncta-tus), an iguana-sized burrow-nesting reptile in NewZealand (Cree et al. 1995), rats probably pose a seri-ous threat to survival of iguanas on several cays andneed to be exterminated soon. Rats may also impactiguana populations indirectly by affecting vegetation,especially on cays with low plant diversity.

The once dense population on Guana Cay(Ostrander 1982) has become greatly reduced inrecent years. A mysterious die-off occurred in spring1994, as evidenced by the discovery of eight adult car-casses and an estimated surviving population of only24 individuals (Hayes et al. 1995). Because the car-casses all appeared to be in similar states of decay,they may have died within a narrow time frame fromsimilar, but unknown, causes. Although natural dis-ease is a possible cause, so too might be mosquitocontrol efforts, recently implemented for the benefitof the growing tourism industry. The ticks whichinfest these iguanas have not been found on any othercay, and may have rendered the lizards more vulnera-ble to the agent(s) causing their deaths. Juvenile igua-nas may also be scarce as a consequence of the die-off; their carcasses may have decayed quickly orescaped detection. However, nesting habitat appearsto be restricted, which could limit the numbers ofjuveniles and affect future recruitment. Nesting habi-tat is also limited on Pigeon Cay and nesting failure isinevitable in wet years when lake surface level inun-dates the nests. It is unclear why the population onGaulin Cay is so low (possibly fewer than 10) andjuveniles appear to be absent. This small, potentiallyinbreeding-depressed population may no longer beviable.

The larvae of a moth (Cactoblastis cactorum) intro-duced decades ago to the West Indies are now rapidlydevastating prickly-pear cacti (Opuntia stricta), animportant food source for iguanas, on several cays.The dense population of lizards on Green Cay is espe-cially vulnerable, particularly since destruction of thecacti will be nearly complete within a matter of years,there are no known means of controlling the moth,and the remaining vegetation (nine plant species) rep-resents a meager diet compared to other rock iguanaspecies (Auffenberg 1982). The impact of this eco-logical disturbance needs to be closely monitored.

Rapid development on the island of San Salvadorwill undoubtedly threaten the populations further.Feral dogs and cats are already numerous in local

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areas, but will increase as more resorts and housingtracts are constructed. This would seriously jeopar-dize any possible reintroductions of iguanas to themainland, unless protected areas of considerable sizecould be set aside. Pollution of Great Lake due toenvironmentally unsound landfill practices maythreaten the fragile mangrove community that harborsa moderate iguana population on Pigeon Cay.Eventually, tourists may discover the attributes of theiguanas themselves, which could increase potentiallydetrimental human-iguana contacts.

Current conservation programsAt present, W. Hayes and R. Carter are collectingbaseline data on all populations of C. rileyi to aid con-servation management decisions. Initial effortsinvolve population surveys, assessment of threats tosurvival, and genetic sampling. Genetic analyses areessential to resolve the taxonomic identities of thenominate taxa, to assess the degree of divergenceamong individual populations, and to evaluate het-erozygosity (which may reveal inbreeding depres-sion). Divergence may be sufficient that the geneticidentity of most or all populations will need to bemaintained.

Further steps include concentrated searches for iso-lated colonies on the mainland and on the southern-most lakes, as well as reintroductions of iguanas topreviously inhabited cays. For San Salvador iguanas,candidate cays for reintroduction (and source animals)include Barn Cay (from Guana Cay), Cato Cay (fromGreen Cay), Cut Cay (from Manhead Cay), and HighCay (from Low Cay). However, further research isnecessary to determine the suitability of each cay, andto assess what corrective actions would be necessaryto render each suitable for reintroduction (e.g.,removal of feral rats or supplementation of nestinghabitat). Reintroduction of iguanas on the mainlandshould be undertaken only if protection of a large areacan be assured. Excellent mainland areas presentlyuninhabited by humans include the land bridge east ofStorrs Lake (where a major resort and marina areplanned), the area between Storrs Lake and GreatLake, and the peninsula east of Pigeon Creek.Additional comparative research planned for the iso-lated populations of this taxon includes vegetationanalyses and studies of reproductive strategies, sea-sonal dietary shifts, and behavioral ecology.

At present, no legal captive breeding programsexist outside the Bahamas. The Bahamian govern-ment has wisely refused to issue export permits forany rock iguana taxa. However, Ardastra Gardens inNassau (New Providence Island, Bahamas) currentlyholds two juveniles and plans to implement an in situprogram. Captive programs could be highly valuable

for repatriation efforts, particularly if the geneticintegrity of individual populations needs to be pre-served.

A public relations campaign is planned to heightenawareness and appreciation among island residentsfor their endemic iguana. Brochures have the poten-tial to provide basic information and to promote theneed for complete protection of the cays on which theiguanas live. Residents should be alerted to the pro-tected status of the iguanas and urged to report toauthorities anyone seen visiting the cays. Bringingferal animals to any cay should be legally forbidden.If possible, especially if the tourism industry contin-ues to escalate, the Bahamas National Trust shoulddeclare the cays a land and sea park and hire a wardento patrol the region.

Critical conservation initiatives• Limitation of access to cays, particularly to dis-courage feeding of iguanas by tourists.• Further protection of the cays by incorporationinto a national park by the Bahamas NationalTrust. As some of the cays are privately owned,this will require working with landowners.• Institutional strengthening of responsible agen-cies to develop enforcement capabilities.• Initiation of a national education program fortourists and residents.

Priority projects1) Continue to sample and survey individual popula-tions on an annual or biannual basis.

2) Eradicate rats on infested cays.

3) Monitor the impact of the Cactoblastis moths andrats on vegetation.

Contact personsWilliam HayesDepartment of Natural SciencesLoma Linda UniversityLoma Linda, CA 92350 USATel: (909) 824-4300 ext. 48911Fax: (909) 824-4859E-mail: [email protected]

Ronald CarterDepartment of Natural SciencesLoma Linda UniversityLoma Linda, CA 92350 USATel: (909) 824-4300 ext. 48905Fax: (909) 824-4859E-mail: [email protected]

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Little Cayman iguana, Cyclura nubila caymanensis; Little Cayman Island;first-year juvenile. Photo by Glenn P. Gerber

Grand Cayman or Blue iguana, Cyclura nubila lewisi; Grand Cayman Island;adult male. Photo by Glenn P. Gerber

Lesser Antilles iguana, Iguanadelicatissima; St. Eustatius,Lesser Antilles; adult male. (Left)Photo by Glenn P. Gerber

Anegada Island iguana, Cyclura pin-guis, Anegada, British VirginIslands; adult male. (Right)Photo by Glenn P. Gerber

Anegada Island iguana, Cyclura pinguis; Anegada, British Virgin Islands; adult female.Photo by Glenn R Gerber

Anegada Island iguana, Cyclura pinguis; Anegada, British Virgin Islands,recently emerged hatchling. Photo by Glenn P. Gerber

Ricord's iguana, Cyclura ricordi; Isla Cabritos, Dominican Republic; adult male.Photo by Bill Christie

Ricord's iguana. Cyclura ricordi; adult male.Photo by Jeff Wines

San Salvador Island iguana, Cyclura rileyi rileyi; vicinity of San SalvadorIsland; adult male. Photo by D. S. Lee/Tortoise Reserve

San Salvador Island iguana, Cyclura rileyi rileyi; vicinity of San SalvadorIsland; adult male. Photo by Glenn P. Gerber

White Cay iguana, Cyclura rileyi cristate; White (Sandy) Cay, Bahamas; adult male.Photo by Bruno Dittmar

Grand Cayman or Blue iguana, Cyclura nubila lewisi. Grand Cayman Island;adult male. Photo by Frederic J. Burton

Lesser Antilles iguana, Iguana delicatissima; St. Barthelemy, Lesser Antilles;adult male basking in tree. Photo by Mark Day

Green iguana, Iguana iguana; St. Lucia; adult male.Photo by Mark Day

Lesser Antilles iguana, Iguana delicatis-sima; St. Eustatius, Lesser Antilles; first-year juvenile. (Left)Photo by Glenn P. Gerber

Green iguana, Iguana iguana; Saba,Lesser Antilles; partially melanistic adultmale displaying. (Right)

Photo by Glenn P. Gerber

Turks and Caicos iguana, Cyclura carinata carinata; Chalk Sound, Turks andCaicos Islands; adult males fighting. Photo by Glenn P. Gerber

Turks and Caicos iguana, Cyclura carinata carinata; Chalk Sound, TCI; adult malebasking in tree. Photo by Glenn R Gerber

Bartsch's iguana, Cyclura carinata bartschi; Booby Cay, Mayaguana; hatchlingPhoto by Glenn R Gerber

Bartsch's iguana, Cyclura carinata bartschi; Booby Cay, Mayaguana; adult female.Photo by Glenn P. Gerber

Rhinoceros iguana, Cyclura cornuta cornuta; adult female.Photo by Glenn P. Gerber

Mona Island iguana, Cyclura cornuta stejnegeri; Mona island; adult female.Photo by Glenn P. Gerber

Jamaican iguana, Cyclura collei; adult male; Hellshire Hills, Jamaica.Photo by Peter Vogel

Jamaican iguana, Cyclura collei; adult female digging nest; Hellshire Hills, Jamaica.Photo by Glenn P. Getter

Jamaican iguana, Cyclura collei; at nest site, Hellshire Hills. Jamaica; adult female.Photo by Glenn P. Gerber

Allen's Cay iguana, Cyclura cychlura inornata; Allen's Cay, Exuma Islands,Bahamas; adult male. Photo by John Iverson

Exuma Islands iguana, Cyclura cychlura figginsi; Central Exuma Islands,Bahamas; adult male. Photo by Chuck Knapp

Andros Island iguana, Cyclura cychlura cychlura; Andros Island, Bahamas;adult male. Photo by Chuck Knapp

Andros Island iguana, Cyclura cychlura cychlura; Andros Island, Bahamas; juvenile.Photo by Chuck Knapp

Cuban iguana, Cyclura nubila nubila; Guantanamo Bay, Cuba; adult male.Photo by Glenn P. Gerber

Cuban iguana, Cyclura nubila nubila; Guantanamo Bay, Cuba; adult males fighting.Photo by Glenn R Gerber

Little Cayman iguana, Cyclura nubila caymanensis; Little Cayman Island;adult male basking. Photo by Glenn P. Gerber


White Cay iguanaCyclura rileyi cristata

By William Hayes

DescriptionThe White Cay iguana is smaller than the SanSalvador iguana (up to 280mm SVL), and can be dis-tinguished by a combination of several scale features,including well-defined postsacral crest scales(Schwartz and Carey 1977). The dorsum of adults isusually gray with brown to orange-brown vermicula-tions. The dorsal crest scales, forelimbs, and portionsof the head and face are typically highlighted inorange. Juveniles resemble young San Salvador igua-nas, but lack a dark area in the pale zone of the mid-dorsum.

DistributionThis subspecies occurs on only a single island, White(Sandy) Cay, in the southern Exumas of the Bahamas.This island is small, comprising about 25ha (Schwartzand Carey 1977). The iguanas were probably muchmore widely distributed during the last ice age whenmany of the Exuma Cays were presumably connecteddue to lower sea levels. They possibly occupied addi-tional adjacent cays in recent centuries, but if so havevanished without a trace.

Status of population in the wildThe single population is confined to only one island,which can support only a limited number of iguanas.According to Lincoln-Peterson surveys conducted in1997, the size of the population has been estimated at150 to 200 individuals.

Ecology and natural historyExcept for informal visits mainly to collect speci-mens, this isolated subspecies has been largelyignored by scientists. Essentially nothing has beenpublished about its ecology or natural history.

HabitatThe vegetation of White Cay is fairly typical of thecoastal rock habitat described by Smith (1993). The

northwestern portion of the cay, where iguanas areleast common, is comprised of a dense forest of thatchpalm (Thrinax morrisii). The remainder of the cay isdominated by Strumpfia maritima and sea grape(Coccoloba uvifera) interspersed among rock andsand. Introduced Australian Pine (Casuarina litorea)is well-established along the low dunes of the south-ern shoreline. Seven-year apple (Casasia clusiifolia)dominates the sand dunes of several smaller cays tothe south that are separated from White Cay by a nar-row tidal flat that iguanas presently do not cross. In1997, the vegetation appeared to be unaffected byHurricane Lily, which scored a near-direct hit inOctober 1996. Iguana density is greatest along theperiphery of the cay where rocky crevices are mostnumerous.

ThreatsIllicit smuggling and the possibility of introduced ani-mals are likely the greatest threats to this population.From photos that appeared in the April 1994 issue ofa popular reptile magazine, it is clear that at leastsome C. rileyi, potentially from White Cay, have beenrecently smuggled. At least eight individuals of C.rileyi, presumably of this subspecies, were discreetlyexhibited in the showrooms of several Florida reptilewholesalers in 1993 (R. Ehrig, personal communica-tion), which suggests that more than a trivial numberof animals were taken. Another potential threat isinbreeding depression, due to centuries or longer ofeffective isolation.

In 1996, S. Buckner, R. Carter, J. Iverson, and W.Hayes observed footprints of a raccoon on White Cay.It may have dispersed there on its own after severalwere formerly introduced to nearby Hog Cay.Although that animal has since been confirmed dead,it appears to have predated a significant proportion ofthe iguana population, particularly juveniles andfemales. Black rats formerly threatened the iguanapopulation, but have since been removed from the cay.

Current conservation programsA grant from the Chicago Zoological Society hasfacilitated eradication of black rats from White Cay.The project was a collaborative effort of the WestIndian Iguana Specialist Group, the BahamasNational Trust, the Bahamas Department ofAgriculture, Fauna and Flora International, LomaLinda University, and Zeneca Agrochemicals, Inc.,which donated the rodenticide used in the eradication.Two cays that appear promising as potential sites forestablishment of a second wild population of theWhite Cay iguana have been identified. Althoughthey have yet to be surveyed on the ground, both lookappropriate from the air, both are Crown land, and

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both have active seabird nesting colonies, a good signthat introduced predators are absent. W. Hayes and R.Carter visited White Cay in 1996 to obtain blood sam-ples and other measurements from the iguanas and toevaluate their status.

Critical conservation initiatives• Acquisition of White Cay within the park sys-tem of the Bahamas National Trust. The islandis remote enough that local policing of the cay isunlikely.• Institutional strengthening of responsible agen-cies to develop enforcement capabilities.• Education programs discouraging visitors to thecay from dumping garbage and feeding iguanas.

Priority projects1) Maintain a program of rat control.

2) Assess the current status of the population, and con-sider candidate cays for establishing a secondary pop-ulation. It might be wise to consider a distant location(such as in the Land and Sea Park of the northernExumas) as a safeguard against extinction resultingfrom weather.

3) Conduct annual or biannual censuses of the popu-lation.




Sandra BucknerBahamas National TrustPO Box N4105Nassau, The BahamasTel: (242) 393-3821Fax: (242) 393-3822Email: [email protected]

Acklins iguanaCyclura rileyi nuchalis

By William Hayes andRichard Montanucci

DescriptionThe Acklins iguana can be distinguished from the SanSalvador and White Cay iguanas by a combination ofseveral scale features, including four rows of scalesbetween prefrontals and frontals, three rows of lore-als, and eight supercilliaries (Schwartz and Carey1977). As in San Salvador iguanas, the caudal verti-cils in Acklins iguanas are not as enlarged as in WhiteCay iguanas and the enlarged postsacral scales form ashorter row. In addition, recent data suggest that theAcklins iguana has significantly more femoral poresthan the other two subspecies (W. Hayes and R.Carter, unpublished data). Like the other subspeciesof C. rileyi, adult Acklins iguanas are strikingly hand-some, resembling San Salvador iguanas withorange/yellow highlights on a darker gray to brownbackground. Juveniles are also similar to those ofyoung San Salvador iguanas.

DistributionNatural populations of Acklins iguanas are found onlyon Fish Cay and North Cay in the Acklins Bight,Bahamas. They formerly occurred on at least Long(Fortune) Cay, and probably once roamed other caysin the vicinity, including the much larger Crooked andAcklins Islands. An additional introduced populationwith five founding individuals became established ona small cay in the early 1970s.

Status of populations in the wildThe two remaining populations in the Acklins Bightappeared to be reasonably healthy when visited by D.Blair in 1991 (Blair 1992a). All size classes were wellrepresented on Fish Cay, but fewer juveniles wereseen on North Cay. In May, 1997, R. Carter and W.Hayes estimated iguana populations on North andFish Cays to be approximately 3,000 and 10,000 indi-viduals, respectively. R. Ehrig and R. Montanuccivisited the introduced population in 1993. They esti-

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mated 140 to 180 individuals present on the cay, pre-sumably all descendents of five founder animals fromthe Acklins Bight (S. Buckner, personal communica-tion). By 1997, the introduced population wasassessed by R. Carter and W. Hayes to consist of 300individuals. The total population is currently estimat-ed at 13,000 or more iguanas.

Ecology and natural historyOnly anecdotal information on the natural history ofthis subspecies is available. Like other rock iguanas,male Acklins iguanas appear to be highly territorial.Males have been observed in jousting matches involv-ing open-mouthed territorial displays, and will chaseother males out of defended areas. Scars in the formof bite marks have been observed which probablyresult from these activities.

HabitatHabitat on Fish and North Cays has not been ade-quately evaluated. The introduced population is prob-ably at or near carrying capacity. Vegetation on thiscay appears to be in excellent condition as determinedby R. Moyroud.

ThreatsNo evidence of feral animals or other threats havebeen identified in the Acklins Bight populations.Introduced hutia (Geocapromys ingrahami) may beaffecting the vegetation on the cay adjacent to thatharboring the introduced population, although theyhave not yet crossed the channel separating the twocays. Further, with only five founder animals, genet-ic heterozygosity of this population may be compro-mised. On all cays, the potential for illegal poachingremains a threat.

Current conservation programsW. Hayes and R. Carter are currently evaluating bodysize and genetic relationships among the three popu-lations. They visited the Acklins Bight in 1996, aswell as the introduced population, in order to obtainblood samples and measurements from the iguanasand to evaluate their status.

Critical conservation initiatives• Acquisition of North and Fish Cays as a parkby the Bahamas National Trust. Both islandswill need to be purchased, as they are privatelyowned.• Institutional strengthening of responsible agen-cies to develop enforcement capabilities.• Initiation of a national education program.

Priority projects1) Accurately census the three extant populations todetermine population size.

2) Assess current threats to each population. Shouldthey become a problem, introduced hutia will need tobe controlled.

3) Explore the potential for restocking vacant cays inthe Acklins Bight with iguanas.

4) Conduct genetic studies similar those being carriedout for the San Salvador iguana. In particular, theintroduced population should be examined.



Richard MontanucciDepartment of Biological Sciences132 Long HallClemson UniversityClemson, SC 29643 USATel: (803) 656-3625Fax: (803) 656-0435E-mail: [email protected]

Robert EhrigFinca Cyclura29770 Mahogany LaneBig Pine Key, FL 33043 USATel/Fax: (305) 872-9811E-mail: [email protected]


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Sandra BucknerBahamas National TrustPO Box N4105Nassau, The BahamasTel: (242) 393-3821Fax: (242) 393-3822Email: [email protected]

Lesser Antillean iguanaIguana delicatissima

By Mark Day, Michel Breuil,and Steve Reichling

DescriptionThe Lesser Antillean iguana attains a smaller overallsize than its only congener the common iguana (I.iguana), with males reaching 430mm SVL (3.5kg)and females 390mm SVL (2.6kg, gravid). LesserAntillean iguanas are relatively stout, and in combina-tion with body color and some convergent behavior,bear a superficial resemblance to rock iguanas. TheLesser Antillean iguana can be readily distinguishedat any age from the common iguana by the absence ofan enlarged subtympanic plate. The two species canalso be distinguished by dark barring on the tail ofcommon iguanas, absent on the tail of LesserAntillean iguanas. The only exceptions are hybridsfound on Les Iles des Saintes and Basse Terre,Guadeloupe. The genus Iguana is distinguished mor-phologically from Cyclura by the presence of gularspikes on the dewlap, and its continuous dorsal crest,which in Cyclura is divided into distinct nuchal, dor-sal, and caudal regions.

Adult Lesser Antillean iguanas exhibit sexualdimorphism in a number of characters. Males possessenlarged dorsal crest scales, especially in the nuchalregion, enlarged gular spikes on the dewlap, andgreater development of the occipital scales. Alldimorphic features give an exaggerated lateral profilewhich is accentuated fully during territorial disputes.In dominant males, both body and tail are dark gray.When males become reproductively active, the jowlsflush pink and the fleshy occipital scales develop apale blue color. Observations of captive individualsindicate that when two males are kept together as partof a group, one will become dominant. If the domi-nant male is later removed, the subordinate male willthen acquire the dimorphic and dichromatic character-istics typical of dominance. Sexual dichromatism isdistinct in the more mesic southern part of the species'range, but is much less pronounced in the xeric sub-populations on limestone islands where large females

eventually develop an overall gray color.Hatchlings and juveniles are bright green. White

flashes on the jaws and shoulders are linked, and thesetogether with usually three vertical white bars on theflanks form disruptive coloration. Dorsal chevrons ofjuveniles darken in response to stress and improvecamouflage, and as a result body color ranges fromgreen to green with brown flashes. Ontogeneticchanges result in the gradual loss of white flashes, anda significant reduction in color change ability. Headcoloration lightens until both sexes have pale headsand uniform green bodies. Early in development, thetail begins to turn brown at the tip and becomes pro-gressively darker rostrally.

No subspecies are recognized. Analysis of geo-graphic variation using multivariate statistical andmolecular genetic techniques is ongoing. Preliminaryresults indicate a low level of geographic variation,but patterns that correlate with island banks.

DistributionUnless indicated, populations refer only to mainislands, and do not imply additional offshore popula-tions on islets (Fig. 9).

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1)2)3)4)

5)6)

7)8)

AnguillaSt. MartinSt. EustatiusSt. Barthelemy, including Ilet au Vent, east of IleFourchueAntiguaGuadeloupe, including Basse Terre, LaDésirade, Iles de la Petite Terre, and Les Iles desSaintes (possibly extinct)Commonwealth of DominicaMartinique, including Ilet Chancel

Historically, this species is believed to have existedthroughout the northern Lesser Antilles, fromAnguilla to Martinique, from sea level up to 300m, inxeric scrub, dry scrub woodland, littoral woodland,and lower altitude potions of transitional rainforest.

Status of populations in the wildInsufficient data currently prevent accurate estimationof population size for the Lesser Antillean iguana.Formal surveys using standardized transect tech-niques have only been conducted for Ilet Chancel(population estimate 200-300) and Terre de Bas (LesIles de la Petite Terre, population estimate 4,000-6,000). Rough population estimates for the remainingislands are based on limited surveys designed pre-dominantly to locate iguanas for morphometric andgenetic data collection. These population estimatesare based subjectively on comparisons of observeddensity of iguanas and the extent of their range with-in each island. In qualitative terms, the

Commonwealth of Dominica is believed to supportthe largest single population due to the extent of avail-able coastal habitat and known distribution, while LesIles de la Petite Terre support the highest populationdensity. However, many populations have beenreduced to extremely low levels in very limited areassuch that their long-term viability is questionable.

Les Iles de la Petite Terre represent the only stablepopulation throughout the species' range. In LaDesirade and the Commonwealth of Dominica wherepopulations are sizeable, there are localized decreasesas a result of habitat loss and hunting, but at presentthese pressures affect a small percentage of the rangewithin each island. In all other cases, populations arebelieved to be decreasing due to a combination ofhabitat loss and fragmentation, introduced predators,browsing competitors, or hybridization with commoniguanas. Museum specimens and publications indi-cate that Lesser Antillean iguanas existed historicallyon Barbuda, Grande Terre (Guadeloupe), IleFourchue, Ile Frégate and Ile Chevreau (St.Barthélemy), Marie Galante, Nevis, and St. Kitts,although precise extinction dates are unknown.

Overall population status appears Vulnerable atpresent due to an estimated population decline ofgreater than 10% per generation for the last two gen-erations and the fact that only two populations exceed5,000 individuals. Populations are critical on Antigua,Anguilla, Ilet au Vent, Les Iles des Saintes, St.Eustatius, and St. Martin. Populations on Basse Terre,Ilet Chancel, Martinique, and St. Barthelemy areendangered, estimated at between 250 and 2,500 indi-viduals. Although populations are somewhat largeron Dominica, Iles de la Petite Terre, and La Desirade,they are still considered vulnerable due to habitatalteration and/or the threat of introduction of commoniguanas.

Ecology and natural historyThe Lesser Antillean iguana occupies islands of thenorthern Lesser Antilles from sea level to approxi-mately 300m elevation, and appears to be limited bythermal requirements. The species exists in xericscrub, dry scrub woodland, littoral woodland, andmangrove, as well as lower altitude portions of transi-tional rainforest. The condition of these habitatsvaries from island to island, with Lesser Antilleaniguanas able to survive in extremely xeric degradedhabitats (< 1,000mm annual rainfall) to mesic forests(3,000 to 4,000mm annual rainfall), in the absence ofintroduced predators or competitors.

Upon emergence from nests, hatchlings disperseinto surrounding vegetation. Both hatchlings andjuveniles live predominantly among bushes and lowtrees, usually in thick vegetation offering protection,

basking sites, and a wide range of food. With age,they climb higher and utilize larger trees. Sexualmaturity appears to be reached at approximately threeyears, although breeding in males is unlikely to beginat this time due to inability to achieve dominance anddefend a suitable territory.

Longevity studies have yet to be conducted, butreliable observations of a population acclimated tohumans include individuals at least 15 years old.Natural predators of juveniles include snakes(Alsophis spp., Boa constrictor nebulosa), birds(Buteo spp., Falco sparverius), and possibly opos-sums (Didelphis marsupialis). Teiid lizards (Ameivafuscata) have been observed predating eggs fromnests, although it is unclear if they actively dig toexpose them. No known natural predators of adultiguanas have been identified.

The Lesser Antillean iguana is a generalist herbi-vore, feeding primarily in the morning, with a diet thatincludes leaves, flowers, and fruits of a wide range ofshrubs and trees including Capparis, Eugenia,Hippomane, Ipomea, Opuntia, Solanum, andTabebuia. Hippomane possesses toxic compoundsthat render it unpalatable to birds and mammals, butdo not appear to affect iguanas. Seasonal variation infeeding ecology exists, with folivory during the dryseason shifting to florivory and frugivory during thewet season. Feeding is selective with fresh leafgrowth, flower buds, and ripe fruits preferred. Seeddispersal by iguanas may be significant for a numberof coastal forest plant species, especially those withlarge or unpalatable fruits which are not dispersed bysmall birds or bats. Differences between populationsin feeding ecology exist, reflecting local variation inplant species composition (either natural or as a resultof introduced browsers). Like its congener the com-mon iguana, the Lesser Antillean iguana has beenobserved by some to be opportunistically carnivorous(Lazell 1973).

Adult males actively defend small territories, atleast during the reproductive period. Most territorialdefense consists of headbobbing and laterally com-pressed profile displays. When in close proximity,side-walking displays give way to head-to-head push-ing contests accompanied by arching of the tail.Fighting occurs infrequently, although severe head,limb, and crest damage has been recorded. Courtshipis limited and mating is typical of other large iguanids.The Lesser Antillean iguana exhibits a polygynousmating system, with male/female sex ratios rangingfrom 1:1 to 1:7. Adult females occupy larger homeranges than adult males, and do not defend them.Female home ranges overlap other females and some-times multiple males. Anecdotal observations suggesta hierarchical structure among females associated

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with a dominant male. In the wet season, groups ofindividuals converge upon certain fruiting trees, orthose with fresh leaves. In these cases, juveniles ofboth sexes feed communally, whereas adults feedtogether only if a single dominant male is present.

Reproduction is timed to maximize hatchlings'ability to feed on nutritionally-rich wet season plantgrowth and grow rapidly prior to the onset of the dryseason. In xeric habitats where seasonal conditionsare most marked, reproduction appears to be roughlysynchronous (e.g., Petite Terre), whereas more mesicpopulations are much less synchronous (e.g., in theCommonwealth of Dominica, gravid females can befound from February to August). The breeding seasonis so prolonged in the Commonwealth of Dominicathat more than one clutch per year may be possible.Females migrate to nesting sites outside their normalhome range, travelling a mean distance of 460m, up toa known maximum of 900m. As migrating femalesoften pass other active nest sites, natal homing mayoccur in this species. Nest sites occur in sandy, well-drained soil exposed to prolonged sunlight, with sim-ple lm long excavated tunnels ending in a chambersufficient for the female to turn around. Clutch size,which may vary geographically, ranges from 8-18(mean egg mass 25g), and is strongly correlated withfemale size. Anecdotal evidence suggests an incuba-tion period of approximately three months.

As Lesser Antillean iguanas occur in several differ-ent habitats with variable environmental conditions,differences between populations in ecology and natur-al history exist. In particular, xeric conditions areassociated with low-lying coralline limestone islandswhereas more mesic conditions occur on mountainousvolcanic islands. Xeric scrub is structurally less com-plex and reaches a lower canopy height than dry scrubor littoral woodland. In these habitats, iguanas exhib-it terrestriality frequently, and will readily drop to theground to escape if disturbed. Terrestrial refugiabetween rocks or in limestone caverns are used forboth escape and sleeping. In more mesic habitats,iguanas are almost exclusively arboreal, feeding intree crowns 30m or more above the ground and mov-ing by jumping between tree crowns.

HabitatDue to extensive habitat alteration, particularly sinceEuropean colonization, for agriculture, timber extrac-tion, and housing, little to no coastal habitat remainsin its primary state in the Lesser Antilles. The onlypossible exception is the proposed ReserveBiologique Dominiale de la Montagne Pelée inMartinique. Nevertheless, rapid natural regenerationis characteristic of hurricane-adapted vegetation, suchthat significant areas of habitat capable of supporting

iguanas still exist. Localized clearance or disturbanceof land for timber extraction or charcoal productionmay result in initial displacement of iguanas, withsubsequent recolonization accompanying recovery ofthe vegetation. Lesser Antillean iguanas cannot toler-ate large scale clearance. Continuous degradation byfree-ranging goats and other herbivores has a slow butserious effect due to the shift in species compositiontowards a high proportion of plants which are eithertoxic or unpalatable (Croton, Lantana, Agave). Areassubjected to browsing pressure support significantlylower iguana populations than comparable habitatswhich are free of introduced browsers.

Suitable habitat is currently shrinking, mostly dueto development. Exclusion or removal of introducedpredators and/or herbivores as part of an ecologicalrestoration program would permit a significantincrease in the amount of habitat available. Les Ilesde la Petite Terre now support the highest known pop-ulation density of Lesser Antillean iguanas despite thefact that the islands experienced extensive cultivationand grazing until the early 1960s.

ThreatsHabitat loss and fragmentation were historically mostextensive on the least mountainous islands, whichhave been systematically cleared for agriculture, espe-cially sugarcane. On these islands, the LesserAntillean iguana has either become extinct (e.g., St.Kitts, Nevis) or remains only in tiny remnant popula-tions (e.g., Basse Terre, St. Eustatius). As tourism hassuperceded agriculture in importance, coastal devel-opment has further reduced the remaining habitat andsignificantly affected already-limited communal nestsites.

Lesser Antillean iguanas are impacted by a range ofintroduced predators. Feral and house cats arebelieved to be significant predators of juvenile igua-nas on Anguilla. On St. Barthelemy, feral predatorsare few, but adult iguanas are known to be killed byguard dogs that run free within fenced property com-pounds where iguanas move to feed. Indian mon-gooses (Herpestes javanicus [=auropunctatus]) wereintroduced to many islands with the intention of erad-icating rats and snakes. Hatchlings and juveniles fallwithin the prey range of mongooses, and on all islandswhere mongooses occur, the Lesser Antillean iguanais either extinct or highly threatened. However, it isunclear how significant the impact of the mongoose iscompared to other factors.

Free-ranging and feral browsing competitors existalongside almost all iguana populations, with thenotable exceptions of Iles de la Petite Terre and mostof the Commonwealth of Dominica. Goat and sheeppopulations are particularly large, and of most con-

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cern on Anguilla, Ilet Chancel, La Desirade, and St.Eustatius, where extensive overbrowsing continues tocause a shift in plant species composition and habitatstructure. Lazell (1973) reported that "huge coloniesswarm on the Ile Fourchue, Les Iles Fregate, and theIle Chevreau, or Bonhomme." Subsequently, massiveoverbrowsing by introduced goats in combinationwith a series of droughts resulted in the extinction ofthese St. Barthélemy offshore populations by the early1990s.

Historically, hunting occurred throughout the rangeof the Lesser Antillean iguana since the time of theAmerindians. Hunting is now illegal throughout thespecies' range. However, St. Eustatius has recentlyexperienced dramatic rises in iguana hunting, causinga crash in the population. Increased hunting waslinked to the influx of construction workers for theexpansion of oil storage facilities on the island, andeconomic problems caused by changes in EuropeanCommunity regulations. Despite recent local legisla-tion, iguana meat continues to be sold locally andtransported to restaurants in nearby St. Martin.Hunting also remains locally prevalent in parts of theCommonwealth of Dominica, where certain popula-tions have experienced rapid unsustainable exploita-tion.

Hybridization between Lesser Antillean iguanasand common iguanas has now been confirmedthrough both molecular genetic and morphometricanalyses from samples taken in Basse Terre(Guadeloupe) and Les Iles des Saintes. The processappears to occur rapidly. In Les Saintes, Lazell(1973) estimated qualitatively that the two specieswere equally abundant in the 1960s, and concludedthat they occurred sympatrically. Morphometricanalysis of specimens collected at that time by Lazellshow that in fact hybridization was already progress-ing. By 1995, less than 10 individuals recognizable asLesser Antillean iguanas could be located, all ofwhich exhibited intermediate species characteristics.In contrast, the common iguana remains extremelyabundant and has extended its range within the archi-pelago. Invasive displacement through competitionand hybridization appears to be the dominant factor inthe disappearance of Lesser Antillean iguanas fromLes Iles des Saintes, due to the absence of other iden-tifiable environmental changes. The same situationhas been documented in Basse Terre (Guadeloupe)and St. Barthelemy, although in both cases it is lessadvanced. Deliberate introduction and subsequentexpansion of common iguanas in Antigua,Martinique, and St. Martin have also been recorded.At present, these are not known to have led tohybridization in Antigua and Martinique, where thetwo species' distributions remain discrete. In St.

Martin, the situation is unclear. Hybridization andaggressive displacement of Lesser Antillean iguanasby common iguanas should be considered potentiallyserious threats to all remaining populations. In 1995,as a result of Hurricane Luis, at least 12 commoniguanas believed to have originated from theGuadeloupe Bank washed up in Antigua, Barbuda,and Anguilla, although most either subsequently diedor were killed for food. Nevertheless, this demon-strates that overwater dispersal of iguanas betweendifferent islands banks may occur.

Road casualties occur regularly along coastal roadswhich bisect iguana habitat in the Commonwealth ofDominica, Basse Terre (Guadeloupe), La Desirade,and St. Barthelemy. In the Commonwealth ofDominica, casualties peak late in the dry season whennumerous gravid females are killed while migrating tocoastal nest sites and early in the wet season whenhatchlings disperse from nests.

Current conservation programsThe Lesser Antillean iguana is legally protected fromhunting throughout its range, but enforcement of theseregulations is extremely difficult and therefore limit-ed. Currently, only a single protected area, the CabritsNational Park (Commonwealth of Dominica) containsa small population. Five additional areas, Les Iles dela Petite Terre (Guadeloupe), the Quill and the Boven(St. Eustatius), and Ilet Chancel and the ReserveBiologique Domaniale de la Montagne Pelée(Martinique), are presently proposed as naturereserves which will protect Lesser Antillean iguanas.Additionally, a number of satellite islets aroundAnguilla, Antigua, Guadeloupe, Martinique, and St.Barthelemy offer significant potential as protectedareas. Following suitable legislative protection andecological restoration, a number of additional islandswould be feasible for translocation or reintroduction.

M. Day is undertaking doctoral research(University of Aberdeen and University College ofNorth Wales) on the population biology of iguanasthroughout the Lesser Antilles. Aspects of theresearch include geographic variation using moleculargenetic and multivariate statistical techniques,hybridization, home range and habitat use, diet, andectoparasites. M. Breuil is undertaking ecologicalresearch on both species in Guadeloupe, Martinique,St. Barthelemy, and St. Martin. In collaboration withAssociation pour l'Etude et la Protection desVertebrés des Petites Antilles, he has begun surveys ofthe proposed nature reserves within the French WestIndies, and is gathering data required for developmentof a conservation management plan for the proposedprotected areas in Guadeloupe and Martinique. A.Alberts is conducting research on variability in the

65

Priority projects1) Implement a series of comprehensive populationsurveys for all populations. The first of these wasundertaken in Anguilla in 1997, with support from the

U.K. Foreign and Commonwealth Office.

2) Assess the potential of additional satellite islands tobecome protected areas for maintaining or establish-ing populations of the Lesser Antillean iguana throughreintroduction and/or habitat restoration (Anguilla,Antigua, Guadeloupe, Martinique, St. Barthelemy, St.Martin).

3) Carry out a long-term ecological study of the xericadapted Lesser Antillean iguana population on les Ilesde la Petite Terre, which, because it is free from ongo-ing habitat destruction, feral predators, and competi-tors, represents the most dense and least threatenedremaining population.

4) Develop regional and national education programsfor schools, other residents, and visitors, utilizing abroad range of media to illustrate the plight of theLesser Antillean iguana and its importance to forestecosystems. National (Breuil, in press) and regional(Malhotra and Thorpe, in press) herpetological guidescan assist in these efforts.

Contact personsMark DayFauna and Flora InternationalGreat Eastern HouseTenison RoadCambridge, CB1 2DTUnited KingdomTel: 44-1223-578464Fax: 44-1223-461481E-mail: [email protected]

Michel BreuilLaboratoire des Amphibiens et ReptilesMusee National d'Histoire Naturelle de Paris25 Rue Cuvier75005 ParisFranceTel/Fax: 33-(0)-1-4305-9043E-mail: [email protected]

Steve ReichlingHerpetarium/AquariumMemphis Zoo and Aquarium2000 GallowayMemphis, TN 38112 USATel: (901) 725-3400Fax: (901) 725-9305E-mail: [email protected]

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protein composition of femoral gland secretions ofLesser Antillean iguanas and common iguanas at theinterpopulation level.

Captive Lesser Antillean iguanas are currently heldat the Durrell Wildlife Conservation Trust (1.1.1),Memphis Zoo (2.2), and the San Diego Zoo's Centerfor Reproduction of Endangered Species (1.1). Allindividuals originate from the Commonwealth ofDominica. Mating has been observed and eggs laid ateach institution. Although most eggs have been infer-tile or non-viable, a single individual was successful-ly hatched at the Durrell Wildlife Conservation Trustin 1997. As the Dominican population is presentlyhealthy, these individuals and their future offspringshould remain in captivity in order to gather hus-bandry expertise, as well as growth and reproductivedata. The long term aim is to gain captive breedingexpertise which can then be applied in situ. Captive-bred individuals could be used for reintroduction tooffshore islands and other protected areas known tohave supported Lesser Antillean iguanas historically,or for restocking depleted populations. Due to con-siderations of geographic variation, reintroductionshould utilize iguanas from the same population orisland bank whenever possible.

Critical conservation initiatives• Implementation of protected areas managementplans for designated nature reserves on les Ilesde la Petite Terre, Ilet Chancel, and ReserveBiologique Domaniale de la Montagne Pelée.• Identification and development of protectedareas at key sites on major islands which remain,or have the potential to be restored to, importanthabitat for Lesser Antillean iguanas.• Development of an inter-governmental agree-ment, including production of accompanyingpublicity materials for airports and ports, toreduce or prevent further introduction of com-mon iguanas onto islands supporting LesserAntillean iguanas.• Development of a species conservation plan forthe Lesser Antillean iguana which would resultin the coordinated implementation of bothregional and national conservation initiatives.The plan would incorporate, but not be limitedto, the priority projects outlined below.

Fig. 9. Present distribution of the Lesser Antillean iguana, indicating the island distribution (but not the distrib-ution on each island) as of March, 1999.

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Chapter 3. Action Plan

Summary of Recommendations

Priorities for recommended conservation action onbehalf of West Indian iguanas are summarized inTable 5. In the subsections that follow, specific guide-lines for implementation are outlined. For the major-ity of taxa, further survey work is required in order todesign effective management and recovery plans. Forsome taxa, existing data are outdated, while for othersonly a limited part of the range has been adequatelydocumented. In other cases, populations are known tobe declining, but quantitative data on rates of popula-tion change and their demographic effects are lacking.For all taxa, population monitoring in the form ofstandardized annual or biannual surveys is critical toupdating conservation priorities and to detecting pop-ulation declines before they have significant demo-graphic impacts and while management interventionis still a viable option.

Many West Indian iguanas remain without ade-quate protection, either because no habitat has offi-cially been set aside for them or because existing leg-islation is only sporadically enforced. To insure thesurvival of all taxa, at least enough suitable habitat tosupport a minimum viable population should be pro-tected by national law in each country of origin.Because the biology of these iguanas varies consider-ably across taxa, particularly in terms of social struc-ture and reproductive ecology, as does the carryingcapacity of the islands they inhabit, the amount ofhabitat required for adequate protection will need tobe determined on a taxon-by-taxon basis.

Control of introduced mammalian predators andlivestock removal are two activities which are crucialto the survival of many West Indian iguanas. Foralmost all taxa inhabiting larger islands, dogs and catsare having devastating consequences, particularly forjuveniles. The recent introduction of black rats to sev-eral iguana-inhabited cays in the Bahamas is alsocause for great concern. Because these iguanas haveevolved in the absence of mammalian predators, theyhave no natural defenses against them and populationdeclines can occur with alarming rapidity. On at leastsome islands, browsing by feral livestock has radical-ly affected the vegetation structure and altered thediversity and palatability of food plants available toiguanas. In addition, trampling of nest and burrowsites by livestock is a serious problem.

Basic research is critical to many if not all of theproposed conservation initiatives for West Indianiguanas. In order to conserve and potentially augment

wild populations, it is necessary to have enough lifehistory data from wild populations to predict the long-term effects of management strategies before they areimplemented. Such data are critical to assessing thecarrying capacity of proposed reserve sites, and todetermining if and when reintroduction or transloca-tion is warranted and feasible. Population modeling,particularly to estimate minimum viable populationsizes and to explore the effects of headstarting, is cru-cial to designing practical conservation strategies thatwill have a high probability of success. Behavioralstudies are needed to understand the conservationimplications of variation across populations and toassess the influence of human impacts. Finally, acomplete study of phylogenetic relationships amongWest Indian iguanas, including both molecular genet-ic and morphological data, is a necessary beginning inorder to adequately rank priority projects and conser-vation initiatives. The availability of such data willcontribute toward a better understanding of adaptivetrends within the group and permit informed extrapo-lations from one taxon to another to be made.

For virtually all taxa of West Indian iguanas, publiceducation is essential. Without effective education atthe local, national, and international levels, other con-servation initiatives are likely to prove futile. ForWest Indian iguanas, educational needs range fromdiscouraging people from feeding, hunting, and trans-porting iguanas between islands, to inspiring local andnational pride for these impressive lizards and theirunique habitats. Raising public awareness regardingthe vulnerability of iguanas to dogs, cats, pigs, andlivestock is critical to preventing their intentionalintroduction to new islands.

Captive breeding programs are recommended forfive of the West Indian iguanas ranked as CriticallyEndangered. Because these taxa have experiencedsignificant population reductions, documented lowpopulation size or a severely restricted range, or anextinction probability of at least 20% within five gen-erations, a captive reservoir is imperative as insurancein the event of extinction in the wild. While such pro-grams have already been undertaken for two CriticallyEndangered taxa (Jamaican and Grand Cayman igua-nas) and are in the planning stages for a third(Ricord's iguana), they still need to be implementedfor two others. A captive program to gain husbandryexpertise has also been recommended for the LesserAntillean iguana. For those taxa for which reducedjuvenile recruitment due to unnatural causes is knownto be a severe threat to survival of the wild population(Jamaican, Grand Cayman, and Anegada iguanas),

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headstarting programs, in conjunction with rigorouspredator control, are recommended as an interim mea-sure to allow for population recovery.

Priority Projects

Based on the degree of endangerment, immediacy ofneed, taxonomic uniqueness, feasibility, and applica-bility of results to other taxa, the following list of pro-jects requiring immediate action has been developed.In the absence of these activities, extinction may beimminent. Additional high priority projects essentialto long-term population viability or the assessment ofsuch are listed within individual taxon accounts. Eachof these projects is critical to the survival of the taxonin question and should be initiated as soon as possible.

Each of the projects below is coded to indicate thegroups which would probably take primary responsi-bility for the recommended actions (1 = GovernmentAgencies, 2 = Non-Governmental Organizations, 3 =Protected Area Managers, 4 = ProfessionalResearchers, 5 = Local Communities). However, forany given project, ideally all of the above groupswould be active participants. Cost estimates are avail-able on request. Projects that are currently underwayare denoted by †.

• Management of the wild population of the Anegadaiguana, including feral animal control, headstarting,and public education (2,4,5) †

• Protection of the Hellshire Hills and extended man-agement of the wild population of the Jamaican igua-na, including release of headstarted individuals andcontrol of invasive predators (1,2,4,5) †

• Protected area planning and habitat acquisitionadjacent to present protected areas for the GrandCayman iguana (1,2,5)

• Maintenance of the Hope Zoo headstart and captivebreeding program for the Jamaican iguana (1,2,4) †

• Initiation of control programs for cats and rats onGrand Cayman, Little Cayman, and Cayman Brac (1,2,4)

• Rat eradication on islands supporting San Salvadoriguanas and continued monitoring of the White Caypopulation (1,2,4) †

• Replacement and extension of pig and goat exclo-sure fences at nest sites of the Mona Island iguana(1,2,3) †

• Mitigation of the Big Ambergris Cay development,including the establishment of a reintroduction pro-gram for the Turks and Caicos iguana (1,2,4)

• Implementation of a long-term field monitoring pro-gram for wild and released Grand Cayman iguanas(2,4,5) †

• Field surveys and ecological studies of Ricord'siguana in the wild, including cat control on IslaCabritos in Lago Enriquillo (1,2,3,4)

• Genetic and taxonomic studies of West Indian igua-nas, especially populations in immediate danger ofextinction (4) †

• Feasibility studies for establishing satellite popula-tions of the Jamaican iguana (1,2,4,5)

• Enhancement of captive facilities and populationsurveys for the St. Lucia iguana (1,2,4)

• Development of a feral animal control program forthe Turks and Caicos iguana (2,4)

• Establishment of protected areas to conserve theLesser Antillean iguana in Anguilla, including feralpredator and livestock control programs (1,2,4,5)

• Establishment of satellite populations of the WhiteCay iguana on suitable restored cays (1,2,4,5)

• Goat removal, rat eradication, and monitoring of thepopulation of Bartsch's iguana on Booby Cay(1,2,4,5) †

• Field surveys to determine population status, range,and extent of poaching of the Andros Island iguana(1,2,4) †

• Implementation of a model public awareness andenvironmental education program using the LesserAntillean iguana as a flagship species for dry forestconservation (1,2,4,5)

• Initiation of a cat control program for Mona Island(1,2,3)

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Table 5. Summary of Recommended Conservation Action for Cyclura and Iguana.

Taxon


Surveys

••

•

••

••

••••••

Protectedareas

•••

•

•

••••••••

Predatorcontrol

•

•••

••••••

Livestockcontrol

•••••

•

•

Fieldresearch

••••

••••••••••

•

Geneticstudies

••

•

•

•

••••

Education

••••••••

••••••

Captive Breeding/Headstarting

••

•••

•

Reintroduction Guidelines

By Richard Hudson

Relocation, repatriation, and translocation (RRT) pro-grams involving reptiles have become an extremelypopular conservation strategy to mitigate the loss ofhabitat, individuals, or populations in areas that haveexperienced declines or extirpations (Dodd and Seigel1991). However, few reptile RRT programs have beensuccessful or properly monitored to determine successor failure. Some notable exceptions include the intro-duction of captive-reared gharials, Gavialis gangeti-cus, to areas where they had been reduced or elimi-nated (Choudhury and Choudhury, 1986); the releaseof over 600 headstarted Orinoco crocodiles,Crocodylus intermedius, in Venezuela (Thorbjarnar-son, 1997); the restoration of Galapagos land iguanas,Conolophus subcristatus, and Galapagos tortoises,Geochelone elephantophus, to areas of former abun-dance (Cayot et al 1994); and the reintroduction ofAnegada iguanas to part of their former range(Goodyear and Lazell 1994). Preliminary observa-tions by Tolson (1996) indicate a successful restock-ing of Virgin Islands tree boas, Epicrates monensisgranti, to an island rendered free of introduced preda-tors, and J. Behler (personal communication) reportssuccessful reintroduction of a group of 76 Gopher tor-toises, Gopherus poylphemus, to St. Catherine'sIsland, Georgia. While representatives from mostreptilian orders have been successfully repatriated

with encouraging results, the outcomes of other well-publicized headstart/release efforts, [e.g. Kemp's rid-ley, Lepidochelys kempi, and other sea turtles(Jacobsen 1993; Bowen et al., 1994) and the PuertoRican crested toad, Peltophryne lemur (Johnson1994)], have proved difficult to monitor and remainquestionable.

While various authors disagree as to what consti-tutes a successful reintroduction (Burke 1991), it isclear that the fledgling science of conservation biolo-gy, including restoration ecology and RRT, cannotstand still while these issues are rectified. Given theenormous loss of biodiversity today, wildlife man-agers need to be willing to consider RRT programs asviable strategies to combat the impending extinctioncrisis. Although by no means a panacea, RRT pro-grams should be considered an option in any recoveryeffort (Burke 1991). However, the technology needsto be refined and improved if these programs are tobecome widely utilized. The methodology and resultsof both successful and unsuccessful RRT experimentsneed to be presented in detail to ensure that futureefforts benefit from past experience (Dodd and Seigel1991).

For West Indian iguanas, it is apparent that at leastthree taxa, the Jamaican iguana, the Anegada iguana,and the Grand Cayman iguana, will require assistancefrom captive headstart/release programs if their wildpopulations are to recover and survive into the future.Both taxa have been reduced to critically low numbersand, given current circumstances and rates of decline,

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appear headed for extinction unless immediate actionis taken.

General ConcernsConservation biology has been described as a crisisscience (Soulé 1985) and as such may not always besubject to the same statistical standards as other sci-entific fields (Burke 1991). Likewise RRT programs,an integral part of conservation biology, are in theexperimental stages. Unfortunately, for some taxa theneed to undertake active recovery strategies, includingRRT programs, is urgent and little time remains forexperimentation. There are few tested standards onwhich to rely, but this alone must not thwart well-con-ceived RRT plans. Bold actions, though exercisedwith due caution, must be taken within the next sever-al decades if several of the more highly endangeredlarge iguanas are to be preserved. Throughout thisprocess, establishment of feedback loops to alter deci-sions based on new and changing data is critical.

Dodd and Seigel (1991) have addressed a numberof topics that should be considered prior to advocatingor undertaking RRT projects, including known causesof decline; biological, habitat, demographic, and bio-physical constraints; population genetics and socialstructure; and disease transmission. Reinert (1991)has expressed concern regarding genetic as well associal considerations, citing examples of aberrantbehaviors in translocated snakes. Burke (1991) ques-tions whether RRT programs are cost effective forimproving species survival, and both Reinert (1991)and Dodd and Seigel (1991) stress the importance oflong-term monitoring to ascertain success. Prior toany reintroduction, the original threats to the popula-tion must be understood and potentially controlled.

The potential to introduce exotic pathogens intonaive natural populations through release of captivereptiles is widely recognized. This route of transmis-sion has been implicated in an epizootic outbreak ofupper respiratory tract disease (URTD) in wild deserttortoises, Gopherus agassizii, in the Mojave Desert ofCalifornia (Jacobsen et al. 1991). Jacobsen (1993,1994) stresses that while reptiles can harbor an arrayof pathogens, the ability to screen for those few thatare known to be significant is crude at best. Theimportance of developing pre-release health screeningprotocols and methods has been emphasized by anumber of workers (Beck 1992; Dodd and Seigel1991; Jacobsen 1994; Raphael 1994). Whenever fea-sible, in situ rearing and headstarting facilities arepreferable to reduce the chances of introduction ofexotic pathogens.

One of the factors that can inhibit the success ofRRT programs is the potential inability of the proge-ny of captive populations to withstand the rigors of

natural environments (Murphy and Chiszar 1989).Chiszar et al. (1994) defined competent offspring asthose possessing the behavioral, anatomical, andphysiological characteristics necessary for survival innatural habitats. The ability of captive-raised animalsto find food and mates, avoid predation, locate refu-gia, and select appropriate microhabitats oncereleased should be investigated (Chiszar et al. 1993).At least in part, deficits in competence may accountfor the lower success rate of reintroductions involvingcaptive-born rather than wild specimens (Griffith et al.1989). Stressing that factors such as strength,endurance, and immunological function are crucial tothe success or failure of RRT programs, Murphy andChiszar (1989) strongly advocate research that rigor-ously assesses competence. In some cases, releasinglarger numbers of animals can at least partially com-pensate for reduced fitness and/or competence of cap-tive-reared specimens (B. Johnson, personal commu-nication).

Although it is commonly assumed that naturalbehaviors are innate in amphibians and reptiles andtherefore present in healthy specimens regardless ofrearing history, no research exists verifying that effec-tive coping skills exist in captive-raised individuals(Chiszar et al. 1993). However, it appears that certainspecies of reptiles can, in the absence of any pre-release training, adapt, survive, and even reproducefollowing release into natural habitat. A recent exam-ple is the monitored release of captive Virgin Islandstree boas onto Cayo Ratones (Tolson 1996). Morethan half of the released snakes survived their firstyear, and at least four of these were neonates. Onefemale released as an adult was recently recapturedgravid.

Several recent conservation programs for iguanasin the Galapagos and West Indies suggest that largeiguanid lizards may be genetically hard-wired formany critical natural behaviors and should be consid-ered viable candidates for reintroduction and popula-tion supplementation.

1) The release of 710 Galapagos land iguanas into thewild over a 10-year period was initiated in 1976 fol-lowing the near extirpation of populations on Isabellaand Santa Cruz by wild dogs (Cayot et al. 1994). Athird island, Baltra, had not supported iguanas sinceWorld War II. The majority of repatriated iguanaswere captive-bred from adults collected from declin-ing populations and reared under captive and semi-captive conditions. The Baltra breeding stock wastaken from a previously relocated population experi-encing poor recruitment. The success of this programhas been impressive, with nearly 400 juveniles and 21adults repatriated on Isabella since 1982. Annual

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monitoring indicates a growing population. In 1991-92, 59 5-year old iguanas were established on Baltra,the first to have existed there in over 40 years. Thesuccess of these programs is encouraging and is close-ly linked to active predator control efforts. Dogs wereeradicated prior to releasing iguanas, and cats are poi-soned semi-annually (Cayot et al 1994).

2) The reintroduction of a group of wild-caughtAnegada Island iguanas to Guana Island in the BritishVirgin Islands has resulted in the successful establish-ment of a second population reservoir for this endan-gered lizard (Goodyear and Lazell 1994). Between1984 and 1987, three males and five females, two ofwhich were gravid, were released on Guana. Onefemale apparently nested successfully, as subadultswere subsequently seen in 1987 and are believed torepresent some of the adults seen in 1991-92. Areproducing population is now established, and a 1992census estimates that about 20 adults and several juve-niles now inhabit the cay. Although still preliminary,these results bode well for re-establishing iguanaswithin their former range. As on the Galapagos, thisproject has entailed the elimination of feral cats.

3) In 1990, the National Trust for the Cayman Islandsinitiated an integrated conservation program for thehighly endangered Grand Cayman iguana, with thelong-term goal of securing wild, reproducing popula-tions in protected areas without the need for constanthuman intervention. The program includes five com-ponents: field research, captive breeding, public edu-cation, habitat protection, and supplementation of thewild population. All components are now in progress,including the first releases, which have proved suc-cessful (Burton 1994b). Although no evidence wasfound of wild iguanas at the potential release site, theSalina Reserve, the area supports suitable habitat. Thefirst three releases were captive-bred, sterilized hybridmales with internal radiotransmitters. The releasesoccurred in June and July 1993, and the lizards weretracked at regular intervals. Although one animal waskilled by a dog outside the reserve, the remaining twoindividuals were still well established at the study sitein December, 1993. These results are encouraging inthat naive captive-bred iguanas demonstrated a sur-prising ability to adapt to life in the wild, locate foodand retreats, and exhibit characteristic territorialbehavior. These results indicate that captive-brediguanas can be successfully re-established in the wildprovided adequate protected habitat can be secured.

Criteria for RRT programsAccording to the IUCN (1995), translocation is thedeliberate and mediated movement of wild individuals

Cayman Islands National Trust iguanaheadstarting facility at the Queen Elizabeth IIBotanic Park, Grand Cayman.

to an existing population of conspecifics. Reintro-duction is an attempt to establish a species in an areathat was once part of its historical range, but fromwhich it has been extirpated or become extinct. Re-enforcement/supplementation is the addition of indi-viduals to an existing population of conspecifics.Conservation/benign introductions are attempts toestablish a species outside its recorded distribution,but within an appropriate habitat and eco-geographi-cal area. These latter introductions should be attempt-ed only when there is no remaining area within aspecies' historical range and enhanced survival of thespecies will result. Although reintroduction is oftenused to describe the release of animals into presentlyoccupied habitat, the term translocation may be moreappropriate in such circumstances. Kleiman et al.(1984) emphasize that the origin of released animals(wild versus captive) may have a major impact on thepotential success of translocation efforts. TheReintroduction Advisory Group of the American Zooand Aquarium Association has prepared a comprehen-sive set of guidelines pertaining specifically to ani-mals born or held in captivity (Beck 1992).

According to the Guidelines for Re-introductionsprovided by the IUCN/SSC Reintroduction SpecialistGroup (IUCN 1995), the objectives of reintroductionare to: a) enhance the long-term survival of a species,b) re-establish a keystone species (in the ecological orcultural sense) in an ecosystem, c) maintain and/orrestore natural biodiversity, d) provide long-term eco-nomic benefits to local people and/or national econo-my, or e) promote conservation awareness. The suc-cess of any RRT effort should be measured in terms ofits goals and objectives. In most cases, success isdefined as a stable, self-sustaining, viable populationat the reintroduction site (Kleiman et al 1984; Doddand Seigel 1991). Burke (1991) discusses concerns

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regarding the point at which a population can becalled self-sustaining and how stability can be objec-tively determined.

Currently, recovery efforts are underway for twoCritically Endangered West Indian iguanas, theJamaican iguana and the Grand Cayman iguana. Forboth taxa, headstarting and supplementation of thewild population are among the primary goals, and pre-liminary releases have already been attempted.

The Cayman Islands National Trust program for theGrand Cayman iguana has multiple objectives, one ofwhich is to generate sufficient offspring for releaseinto suitable habitat. Unfortunately such habitat isbecoming scarce on Grand Cayman, and feral preda-tors are an increasing problem. Establishing a stablepopulation on protected property is critical, and theproposed Salina Reserve site is promising in thisregard. A Trust-owned property, the Queen ElizabethII Botanic Park, is protected and may provide suitableiguana habitat as evidenced by the presence of a resi-dent male over the past three years and a successfulpilot release in 1994. Park development has improvedhabitat suitability in recent years, and the area lacksonly nesting sites and associated retreats. It is hopedthat the release of females within the park will attractroaming males, which usually maintain extensivehome ranges, from outlying areas, thus providing asecond area from which to repopulate other sites.While it is apparent that recovery of Grand Caymaniguanas will require a multi-faceted approach, reintro-duction clearly constitutes a necessary component ofthis program.

A similar situation exists for the Jamaican iguana.Considered extinct for nearly half a century, theJamaican iguana was rediscovered in 1990 and hassince become the subject of intense conservation andresearch efforts. Existing only in the dry limestone

A group of headstarted iguanas at the Hope Zooin Kingston, Jamaica.

forests of the Hellshire Hills region of southeastJamaica, a remnant population of perhaps 100 animalssurvives. Two active nesting sites were discovered in1991, and field work has focused on protecting thesesites and deterring hunters and charcoal burners fromcore iguana areas. High juvenile mortality associatedwith mongoose predation is widely recognized as thesingle most important factor keeping this populationat low levels. A 1993 Population and Habitat ViabilityAssessment workshop indicated that without reducingjuvenile mortality through headstarting, this smallpopulation was headed for extinction within 50 years.The recovery strategy includes guarding nests andharvesting 50% of the hatchlings for headstarting atthe Hope Zoo in Kingston. Headstarted iguanas willbe released after 4-5 years, when presumably they willbe large enough to avoid mongoose predation.Control of feral dogs and mongooses will need to beimplemented concurrently to increase survival of thereleased iguanas.

Pre-release considerationsIn preparation for the eventual release of headstartedJamaican iguanas into the wild, a pre-release medicalscreening protocol was developed in 1994 to assessthe health status of the captive colony at the HopeZoo. Cloacal cultures and fecal exams were conduct-ed to screen for abnormal internal parasites and bacte-rial pathogens, and blood chemistry panels were per-formed to establish normal values. Attempts to sam-ple the wild population in order to correlate captivevalues with those of free-ranging counterparts alsoneed to be made. Similar health screening programsshould be incorporated into pre-release preparationsfor any iguana species destined for release to the wild(Alberts et al., 1998). This is especially important ifiguanas have been in captivity for a long period oftime, or have lived in colonies that have experiencedany health problems or disease. An Amphibian andReptile Veterinary Advisory Committee, establishedunder the American Zoo and Aquarium Association,has published recommended protocols for quarantineand pre-release health screening. This group is avail-able to assist with this process, and information can beobtained from: Bonnie Raphael, D.V.M., AnimalHealth Center, Bronx Zoo/Wildlife ConservationPark, 2300 Southern Boulevard, Bronx, New York,10460 U.S.A., Tel: (718) 220-7104.

Other forms of pre-release conditioning may benecessary as well. The original release strategy forJamaican iguanas called for a hardening facility to bebuilt in the Hellshire Hills for acclimating headstartediguanas to wild forage and local conditions. Due tofinancial and logistical constraints, this idea was tem-porarily abandoned in order to assess the survival rate

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of iguanas taken directly from the Zoo. After fiveyears of headstarting, the first pair of iguanas was fit-ted with radiotransmitters and released at their hatchsites in March 1996. Experiences from 1995 hadshown that radiotagged hatchlings released near thenest site tended to remain in the same vicinity, and itwas hoped that older iguanas would display a similarsite fidelity. Results were mixed, with both animalsexperiencing some initial weight loss and the malelosing his transmitter. Whether this was related toweight loss is unknown; the female also lost consider-able weight and was recaptured so that her transmitterattachment could be secured. She was released again,and was apparently feeding and doing well soon after-ward (N. Mitchell, personal communication). Sixadditional iguanas released in 1997 all appear to haveadapted well.

Radiotracking released iguanas in the HellshireHills, Jamaica.

Significant differences exist in the feeding regimesof the Grand Cayman and Jamaican iguana headstartprograms that may have serious implications for thesurvival of released iguanas. Captive Grand Caymaniguanas are raised almost entirely on commerciallyavailable alfalfa-based livestock pellets. Because theyare unfamiliar with fruits and vegetables, they may bemore inclined to feed on native vegetation oncereleased. In contrast, Jamaican iguanas are primarilyfed commercially available fruits and vegetables.This diet is highly palatable to the iguanas, and theyconsume it readily and grow rapidly. However, itshigh moisture content may predispose iguanas to sub-stantial water weight loss following release.Furthermore, ingestion of a highly palatable fruit dietas a primary food source may cause iguanas to adapt

more slowly to native vegetation. Given this, accli-mation of headstarted iguanas to natural foods prior torelease may be advisable.

Financial considerationsBased on limited experiences with iguanaheadstart/release programs on both Grand Caymanand Jamaica, it is apparent that practical financial con-siderations must be evaluated prior to developing arelease strategy. Depending on the length of the pro-gram, the headstarting process itself represents a sub-stantial monetary commitment, although this isreduced somewhat if done within the range country.Although over $20,000 was raised in the United Statesto fund the new iguana management facility at theHope Zoo, the 2-year old facility is at capacity andneeds expansion. The National Trust's new iguanafacility cost a total of $14,700, donated from a singleoutside source. In addition to the expenses of pre-release conditioning and health screening, facilityconstruction alone can impose a considerable finan-cial burden on local conservation efforts.

Expenses do not end once animals have beenreturned to the wild. In fact, the most costly aspect ofheadstart/release programs may be field monitoring,which is critical to all RRT programs. If radioteleme-try is utilized, and this certainly appears to be the mosteffective method of gauging short-term survival, thencosts increase considerably. Even after the initialexpenses of equipment purchase, the annual cost ofthe Jamaican iguana field project is estimated at aminimum of $10,000 U.S., excluding an additionalfull-time employee. According to Kleiman et al.(1984), the most effective and successful RRT pro-grams have been comprehensive efforts involving alarge multidisciplinary team and considerableresources. These authors discuss 13 criteria thatshould be considered prior to implementing a reintro-duction (Table 6).

RRT technology and its application to iguana con-servation is in its infancy, and there is much to belearned as this process moves forward. But is it onlyby moving forward that we will begin to gain theexperience and insights necessary to make thesestrategies successful. In particular, radiotelemetrytechniques must be further developed and openlyshared. Conservation strategies must be developedwhile time remains to refine the methodology and per-fect the techniques that will ultimately prove to be anessential component of recovery strategies not onlyfor endangered iguanids, but other taxa as well.

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Table 6. Translocation/Reintroduction of Grand Cayman and Jamaican iguanas: Do appropriate conditionsexist? (Scale 5 = best).

Recommended reintroduction/translocation? Yes Yes

† Although the causes of decline have not been eliminated, they have been researched and plans to mitigate themare underway.

‡ Key habitats for both taxa have been identified but have yet to achieve formal protection.

Translocation to Unoccupied Habitat

By James Lazell

West Indian iguanas seem in general to be a resilientgroup of organisms able to survive in depauperateecosystems and arid situations. These large lizardsseem not to have been affected by Holocene climaticchanges that arguably contributed to historical extinc-tions of rodents, monkeys, sloths, and tortoises. Eventhe arrival of Amerindians three or four thousandyears ago seems not to have exterminated any taxa.European colonizations, however, and especially theexotic species accompanying them, have been devas-

tating. Nevertheless, West Indian iguanas have beensuccessfully introduced to many areas now dominatedby human disturbance. The prospects for restorationof iguanas to previously occupied portions of theirranges seem quite sanguine. In selecting sites fortranslocation, the following issues should be consid-ered.

Historical presenceMuseum specimens, literature records, fossil and sub-fossil remains, and local testimony can all serve toindicate previous presence, and this is the best initialevidence for at least potential habitat suitability. Itcan probably be presumed that iguanas occurred

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11.

12.13.

Reintroduction technology known/in developmentKnowledge of species' biologySufficient resources exist for program

33

Yes

33

Yes

Biological and other resources

7.8.9.10.

No negative impact for local peopleCommunity support existsGOs/NGOs supportive/involvedConformity with all laws/regulations

YesYesYesYes

YesYesYesYes

Biopolitical conditions

4.5.6.

Causes of decline removed †Sufficient protected habitat ‡Unsaturated habitat

NoNoYes

NoNoYes

Environmental condition

1.2.3.

Need to augment wild populationAvailable stockNo jeopardy to wild population

YesYes

?

YesYes

Condition

Grand Cayman iguana Jamaican iguana

?

throughout the coastal lowlands of any island bankthat has an island on it where iguanas demonstrablyoccur or occurred in the recent past. Given glacialmaximum low sea levels as recently as 10,000 yearsago, there appears to be little that would have deterrediguana dispersal. Tiny islands, of course, might fail tosustain populations following post-glacial rise in sealevels. For example, rock islets like Monito mightprovide no suitable nesting soils or even sufficientvegetation to feed a viable iguana population. Still, itis expected that iguanas would have originally beenpresent on most islands on occupied banks down to atleast 100ha in area. The propensity of West Indianiguanas to survive, often in abundance, on very smallcays is heartening.

Exotic predators and competitorsThe different species of iguanas show a spectrum ofabilities to deal with predators, especially mammaliancarnivores. Some forms, like the rhinoceros iguana onHispaniola or the Cuban iguana now introduced toPuerto Rico, seem able to survive and reproduce insympatry with dogs, cats, mongooses, and even peo-ple who eat them. Other forms, like cornuta onchiop-sis of Navassa and pinguis on Puerto Rico, wentextinct so rapidly after European colonization thattheir existence has been very scantily recorded. Siteswhich are free of exotic predators, especially dogs,cats, and mongooses, hold the greatest promise for re-establishing populations.

Goats are the most efficient and detrimental ofcompetitors, and it is often very difficult to extirpatethem. Because goats are so versatile and opportunis-tic in their diets (to the extent of climbing trees anddevouring plants often toxic to other species) iguanaswould probably be unable to establish populations onislands with saturated goat populations. That iguanapopulations dwindle in the presence of introducedlivestock is evidenced by the situation on Anegada inthe British Virgin Islands. Although active reproduc-tion is occurring and seemingly healthy hatchlings canbe found, lack of available plant food may precludejuveniles from ever adopting a diverse and healthyherbaceous diet. The presence of young iguanas can-not be taken as evidence of a healthy populationbecause exotic competitors may prevent them fromever reaching maturity.

Other iguana species, such as the now widely intro-duced common iguana, may be very effective com-petitors. Further, introgressive hybridization mayoccur between an introduced iguana species and thepreviously incumbent native, as seems to have hap-pened in Les Iles des Saintes. In sympatry, it general-ly appears that one iguana taxon either out-competesor genetically swamps another. Therefore, attempts to

establish sympatry should be avoided.

Microhabitat conditionsIguanas have to be able to dig holes to lay eggs. Manyspecies utilize beach berms, while others excavateinland soils. The requirements of each must beaccommodated. Very small islands are especiallylikely to lack potential nesting sites.

Iguanas seem to do best in places where the sunreaches them early in the morning, particularly on flatislands, ridge tops, and east-facing slopes. On GuanaIsland, Goodyear and Lazell (1994) found that evenlarge males climb trees in the evening, seemingly tobe in good positions for early insolation. This maymean that densities on hilly islands with west-facingslopes will be lower (other factors being equal) thanon flat islands. Circumstantial evidence on GuanaIsland indicates that hatchlings move from their nestsites principally into areas with early morning directsun. This may limit dispersal on hilly islands to east-facing slopes that rise west of suitable nest sites.Evidence on these points is scanty at best, but theirconsideration can only improve restoration prospects,and suggest valuable lines of future research.

Potential for human interactionsGenerally, human interactions with wild iguanas arenegatively perceived. Traditionally, people havekilled iguanas in the West Indies to eat them, orbecause they viewed them as agricultural pests, orbecause they fear any large wild animal, or for sport.All of these reasons are potential causes for concernover the fate of translocated iguanas, and should beamong the most obvious factors considered in suchplanning. On the other hand, human interactions cansometimes also be very beneficial. Many people,including tourists, are enthusiastically fond of igua-nas. They will go out of their way to see and photo-graph iguanas, and delight in the antics of semi-tameindividuals. On Anegada, at least a few iguanas didwell despite dogs, cats, goats, and usually hostilehumans because one individual liked them enough toset up a feeding station.

While a dim view of subsidizing wild animals isusually taken because this is not regarded as being intheir long-term interest, feeding stations may beappropriate during the early stages of translocation.Also, the popularity of iguanas at a particular site maybe a factor in their protection (e.g., from dogs), andmay help insure that new populations are monitored atleast informally.

Genetic considerationsMuch has been made of inbreeding depression andgenetic problems associated with small numbers of

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founders. However, it is a certainty that many naturalpopulations of West Indian iguanas were derived fromone or a few founders, and subsequently did quitewell. Different taxa vary in their reproductive capac-ity, but all are relatively fecund. Although a greaternumber of founders is preferable, it is probably thecase that even a single healthy, gravid female canestablish a successful population. From a dispersalistpoint of view, this is most likely the way all knowntaxa of West Indian iguanas originated.

ConclusionsIn summary, iguanas are apt to do very well on smallislands, provided these islands have been cleared ofgoats, mongooses, and other detrimental exotics, andthat the vegetation either remains in or has recoveredto a near-natural state. Islands with tourist presencemay be especially suitable because feral livestock areoften removed from them and interested people willtend to mitigate deleterious acts, such as killing bydogs or humans, and help to monitor iguana numbers.

Marking Techniques

By William Hayes, Ronald Carter,and Numi Mitchell

Iguanas can be marked for research purposes eithertemporarily or permanently using a variety of method-ologies. Some techniques allow for individual identi-ty, while others indicate only whether the animal hasbeen sampled or not. Further, while some methodsrequire recapture to determine individual identity, sev-eral techniques allow recognition of individuals with-out the need for recapture. The importance of choos-ing an appropriate marking technique is illustrated bythe experience of workers at the Hope Zoo in Jamaica(Hudson 1994). Captive-hatched Jamaican iguanaswere initially marked with paint and photos weretaken of head scalation patterns. Over time, however,the paint markings vanished and the scalation patternsproved unreliable. As a result, the identities of indi-viduals had to be verified later by genetic analyses.

Selection of marking method depends on the natureof the study, and should take into consideration thenumber of times animals will be sampled, whetherdata from individuals are important, and constraints oftime and money. Also important is whether a particu-lar marking system might compromise collection ofcertain data. For survivorship studies, conspicuousmarks could increase risk of predation, particularlyfor juveniles. In addition, the regulating agency grant-ing permission for the work may object to or favor

certain techniques, especially when endangered taxaare involved.

Temporary marksPainting and tagging are commonly used techniqueswhich permit recognition of previously sampled indi-viduals over the short term. Moreover, they can beused for individual recognition without the need forrecapture. For example, J. Iverson (personal commu-nication) and C. Knapp (1995) applied fingernail pol-ish or enamel paint to the dorsum of Allen's Cay igua-nas and Exuma Island iguanas in the field to recognizeand avoid recapturing animals. Wiewandt (1977),using a plastic dart gun, and Iverson (1979), employ-ing a squirt gun-like syringe, painted the dorsum ofiguanas from a distance to individually mark andstudy the behavior of Mona Island iguanas and Turksand Caicos iguanas without the need for disruptivecapture and handling. Alphanumeric characters paint-ed on the dorsum have been used in the field to rec-ognize individuals of Exuma Island iguanas (Coenen1995), desert iguanas (Glinski and Krekorian 1985),chuckwallas (Smits 1985) and marine iguanas (Laurie1989; Wikelski and Trillmich 1994). In general,enamel paint will remain on the integument of iguanasfor months, usually until the animal sheds. Henderson(1974) used a felt-tip pen to mark numbers on the dor-sum of common iguanas but the marks faded afterseveral weeks. As a general rule, red marks shouldprobably be avoided because iguanas are highlyattracted to this color and will bite at it persistently (J.Lazell and N. Mitchell, personal observation).

Tags of various sorts can also be employed formarking purposes. For example, Minnich andShoemaker (1970) marked desert iguanas with col-ored cloth tape around the base of the tail, Henderson(1974) tied small bells to the necks of common igua-nas with fishing line, and Rao and Rajabai (1972)tagged agamid lizards with different shapes of coloredaluminum rings placed around the thigh. Leg bandsare used routinely for marking birds and could alsowork well for iguanas.

Permanent marksAlthough many permanent marking systems requirerecapture of study animals to establish individualidentity, some allow for recognition of free-rangingindividuals without the need for recapture. Toe-clip-ping is the most widely used technique for perma-nently marking lizards (Ferner 1979), and has beenemployed in long-term field studies of Allen's Cayiguanas (J. Iverson, personal communication). Usinga coded system, the number of individuals that can beuniquely marked is substantial (Ferner 1979). Whileconcerns about pain and potential harmful effects

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resulting from missing toes exist, toes are frequentlylost naturally and no studies to date have shown thattoe loss compromises survival of lizards (Dodd 1993).When toe-clipping is the only method used, animalsmust be recaptured to confirm individual identities,and confusion may result if additional toes are lostsubsequent to marking. Branding the integument ofanimals with unique marks can be accomplished byheat or freezing (Ferner 1979; Honneger 1979). M.Wikelski and D. Werner (personal communication)have used heat branding to mark alphanumeric codeson marine and common iguanas with no ill effects.These brands can be read only at close distances, butcan be combined with more visible but temporarypaint marks.

Affixing colored glass beads to the nuchal crest hasrecently become popular among investigators study-ing large iguanas (Rodda et al. 1988; van MarkenLichtenbelt et al. 1993; G. Gerber and A. Alberts, per-sonal communication; W. Hayes and R. Carter,unpublished studies). This method, developed foriguanas by Rodda et al. (1988), can be applied notonly to adult iguanas but also to juveniles, as the num-ber and sizes of beads affixed to the crest can beadjusted for animal size. Pain and ill effects associat-ed with the procedure appear to be minimal.Occasional loss of the beads has been noted (Rodda etal. 1988; W. Hayes and R. Carter, unpublished obser-vations), most likely resulting from degradation ofbeads (especially if plastic) and suture material (usu-ally monofilament line), or biting of the beads by con-specifics. Glass beads not only retain their color bet-ter than plastic beads, but are also superior in resis-tance to crushing. Suture material should be selectedfor resistance to degradation by ultraviolet light. Thebeads are fairly visible from a distance, especiallywith the aid of binoculars, making this technique valu-able for mark-recapture studies.

A potential drawback to color-coded beads is thattheir conspicuousness may render marked animalsmore visible to predators. This evidently was not aproblem for common iguanas on the mainland (Roddaet al. 1988), and the adults of large insular taxa such asrock iguanas are generally under reduced predationpressure. Because iguanas are inclined to taste ortongue-touch brightly colored objects, juvenilesmarked by this method could potentially be injured orkilled by curious adults. Conceivably, the brightlycolored beads could also influence mate choice, as hasbeen demonstrated for colored leg bands in certainbirds (Harvey 1986). Finally, visitors to natural igua-na populations may find the color markers to be ofinterest, as evidence that someone cares enough tostudy the animals, or as an unattractive distraction.More study of the consequences of colored bead

Color-coded glass beads attached to the crestare being used increasingly for permanentmarking of iguanas.

marking is needed to adequately evaluate their effec-tiveness.

Passive integrated transponder (PIT) tags havereceived attention recently as a means of permanentlymarking animals for unambiguous individual identifi-cation. PIT tags contain a unique magnetic signaturepackaged within a tiny glass capsule, and a virtuallyunlimited number of codes are available. They areusually inserted by syringe just beneath the surface ofthe skin. For larger animals, insertion into the thigh isrecommended, while for hatchlings and smaller juve-niles, the inguinal region is preferred. Upon recap-ture, a hand-held, battery-powered transponder ispassed within a few centimeters of the animal toobtain a reading of the tag's unique identificationcode. Although this technique has primarily beenused in captive recovery programs (e.g., GrandCayman and Jamaican iguanas, R. Hudson, personalcommunication), J. Iverson, F. Burton, P. Vogel, andA. Alberts have begun to use the method in the field.PIT tags have the added advantage of offering lawenforcement officials the possibility of proving smug-gling charges should animals having implants appearin the international wildlife trade. All field investiga-tors of endangered taxa should consider adopting thistechnique, at least as a secondary marking system.Unfortunately, some of the more sophisticated animalsmugglers and dealers have become alert to the possi-ble presence of PIT tags, and purchase their ownreceivers to detect and remove them.

RadiotelemetryRadiotelemetry has proven to be a useful tool in eval-uating aspects of West Indian iguana ecology andmanagement strategy. It has provided information

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about home range and social structure for iguanas onAnegada Island and in the Lesser Antilles, and isbeing used to monitor the reintroduction of headstart-cd Jamaican iguanas, released as subadults into theHellshire Hills region.

Two-stage external transmitters have been mosteffective for studies of wild iguanas because they cansupport relatively large antennas (e.g., 1/4l whips)which give greater range of reception. This is impor-tant for species with large home ranges or those usingunderground refugia. External tags may also be fittedwith larger batteries than internal tags, which decreas-es the frequency of battery replacement and handlingof animals. Externally mounted tags, however, aremore apt to be damaged by sun or battered in rockyhabitats than internal tags.

Transmitters have been mounted successfully onneck collars (M. Day, personal communication), waistbelts (N. Mitchell, 1999), and shoulder harnesses (R.Hudson, personal communication). For moreapproachable animals, two-stage tags with small wireloop antennas (originally designed for rats) have beenimbedded in paraffin, coated by a thin layer of dentalacrylic, wrapped in chicken skin, and placed in loca-tions where iguanas will encounter and ingest them.This technique has yielded four to seven days of dataafter which the tag is expelled with the feces(Goodyear and Lazell 1994). An advantage of thismethod is that the animal need not be handled.Animal positions have been determined by triangulat-ing remotely using receivers at fixed telemetry sta-tions or by directly approaching the animal andrecording its location using a global positioning sys-tem. Collapsible yagi antennas used with smallreceivers work well in the dense scrub and forest habi-tats occupied by many iguanas.

Population Monitoring

By William Hayes and Ronald Carter

A first step in developing conservation plans to protector restore remaining iguana populations is to assessthe status of populations in the wild. Once a conser-vation plan has been implemented, continued popula-tion monitoring is essential to evaluate the effective-ness of the program. Despite the recent attentiongiven to several taxa, information as basic as popula-tion size is still lacking for many West Indian iguanas(Blair 1991a, 1994). For some taxa, the only dataavailable are subjective impressions based on only afew hours of observation (Blair 1991b, 1992a,b;Ostrander 1982). Some estimates of abundance aredecades old, whereas others urgently need to bereassessed due to recent threats to the population.Although rough estimates are important when nothingelse is available, they are of limited value for estab-lishing priorities and developing long-term survivalplans.

Population estimates based on rigorous samplingare sorely needed, not only to update the endangeredstatus of many taxa but also to monitor the success ofconservation efforts. While numbers at or near carry-ing capacity suggest a healthy population, decliningnumbers or the absence or scarcity of certain sizeclasses may be indicative of deteriorating habitat, dis-ease, or the presence of introduced flora or fauna.Population viability can be better understood byrepeated surveys that yield information on growth

A shoulder harness attachment forradiotransmitters has been used successfully inthe Hellshire Hills, Jamaica.

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©R

ick Reed

rates, sex ratios, reproduction, age of sexual matura-tion, and survivorship. Likewise, injury frequencies,habitat requirements and preferences, and movementpatterns can be ascertained. Accurate surveys are par-ticularly important for setting conservation prioritiesand allocating limited resources appropriately.

Standardization of all iguana population surveys,regardless of taxa, location, and purpose of study, isprobably not possible because different habitats andstudy objectives require different techniques.Nevertheless, population estimates should be based onappropriate considerations, and uniformity of multiplesampling efforts is necessary for comparative orexperimental studies. Because objectives of abun-dance estimation and hypothesis testing are different,as are their design requirements, investigators shoulddetermine whether the purpose of the study is to eval-uate population density, population size, or rate ofpopulation change before embarking on any study ofpopulation numbers (Skalski and Robson 1992).Inferential studies are especially important to under-stand how population density changes across a gradi-ent, varies over time, or differs among islands or treat-ment conditions. Constraints involving costs, man-power, and time must also be considered. Knowledgeof methodological assumptions is critical in order thatsteps can be taken to ensure they are met in the field.Preliminary sampling can provide valuable insightson how to design an effective study, and prior famil-iarity with data treatment and adequate training ofobservers are essential.

A vast array of population estimation techniquesare available, many of which are tailored to meet spe-cific sampling conditions and requirements. Theirspecialized applications, assumptions, and calcula-tions have been treated in detail by other investigators(Bibby et al. 1992; Skalski and Robson 1992;Buckland et al. 1993). Although less complex, single-sample techniques are not as accurate as many of themore complicated methods involving repeated sam-pling. The latter can be particularly sophisticated, andcomputer programs are now available to simplifycomputation.

While the terms census and survey are often usedinterchangeably, Buckland et al. (1993) emphasizethat a census requires counting all subjects within asample area (only rarely accomplished), whereas asurvey samples only a portion of animals within anarea. There are two basic approaches used for con-ducting population surveys. Distance sampling focus-es on representative transects, estimates populationdensity for those areas, and then extrapolates popula-tion size assuming a similar density for the entire area.Mark-recapture studies involve the capture and mark-ing of a subset of animals in the population which,

based on the ratio of marked to unmarked animalsdetermined from subsequent sampling, is used to esti-mate total population size. The advantages and disad-vantages of each approach are outlined in Table 7.Two of the most important considerations regardlessof the approach are the need for control populationswhen possible and the use of randomization and repli-cation of treatments whenever possible to increaseprecision (repeatability) and accuracy (proximity toactual population density or size) of estimates andprovide valid and appropriate inferences on popula-tion abundance (Skalski and Robson 1992).

Distance sampling methodsMany West Indian iguanas occupy relatively largeislands where it is not practical to count animals overthe entire island. In such cases, population estimatesmust be based on population subsampling, for whichdistance sampling is particularly useful. Classicaltransect studies are a subset of, but distinct from, dis-tance sampling models (Buckland et al. 1993). Inclassical transects, several linear transects or circularplots are randomly situated in appropriate habitat.Observers then proceed along the transect line orremain stationary at the center of the circular plot,counting all animals detected within a predetermineddistance from the transect line or central point. Nodistances between the animal and the transect line orcentral point are measured. These methods assumethat all animals within the sample area are encoun-tered, which in virtually all cases is a practical impos-sibility. Because of this, classical transects nearlyalways underestimate animal density. Consequently,despite the much greater effort and expense required,mark-recapture studies have often been employedwhen precision is important.

Distance models, refined over the last two decades(Buckland et al. 1993), require measuring the perpen-dicular distance between the transect line or centralpoint to where an animal is first seen. Boundaries ofthe sample area need not be established, and use of aunique detectability function precludes the assump-tion that all animals in the sample area are detected.The detection function specifies probabilities ofdetecting an animal in relation to distance from thetransect line or central point, allowing estimates ofdensity to be made under mild assumptions withgreater accuracy than is normally achieved with clas-sical transect methods. Assumptions of classical anddistance models are compared in Table 8. Use of thecomputer program DISTANCE greatly facilitatesanalysis of data generated by distance sampling(Laake et al. 1993).

For distance sampling, line transects are most oftenused, especially in relatively open habitat, but point

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sampling may be preferable in denser habitat or underother circumstances. Other applications of distancesampling, such as trapping webs and indirect countsof scats, burrows (Iverson 1979), or other signs, canbe regarded as modifications to the basic distance the-ory (Buckland et al. 1993). The lengths of line tran-sects must be known, and care must be taken to estab-lish transects that are straight, randomly placed with-in representative habitats, far enough apart to avoiddouble-counting of animals, and preferably parallel toone another and to any known density gradient.Established routes such as roads and ridgetop trailsare subject to bias and should be avoided, and clus-tered populations warrant special consideration(Buckland et al. 1993). Preliminary surveys are par-ticularly important for making decisions on transectdesign. Buckland et al. (1993) offer an excellent dis-cussion on strategies for placement of lines or pointsacross areas to be sampled.

The measurement of distances can be unwieldy,making distance methods more time-consuming thanclassical transects, particularly when departure fromthe transect line is necessary to mark or measure thepoint where each animal is initially seen. Such inter-ruptions may also disturb nearby animals. New andrelatively inexpensive technologies, however, cangreatly expedite data collection. Rangefinders orbinoculars with reticles can be used to estimate dis-tance without the need to leave the transect line, andsimultaneous estimation of the sighting angle relativeto the transect line can be accomplished using a handheld angle board or an angle plate on a tripod(Buckland et al. 1993). By rapidly collecting andrecording distance and angle measurements for eachanimal seen, perpendicular distances can be easilycalculated later using a trigonometric function.Cruder methods such as pacing and visual distanceestimation can be used if the sacrifice in accuracy isacceptable. However, accuracy of distance measure-ments is critical when close to the transect line due tothe mathematical properties of distance models.When distance estimates are less accurate, roundingto convenient values and collapsing of data into dis-tance categories is commonly practiced, as is trunca-tion, the setting of a limit to the furthest distance ani-mals are counted. Although outliers can be removedbefore analyses, caution must be taken not to intro-duce systematic bias.

The transect design should provide for adequatesample size. As a general rule, the minimum samplesize of all transects combined should be 60-80 indi-viduals, although 40 may still provide reasonable pre-cision (Buckland et al. 1993). Somewhat larger sam-ples are recommended for point sampling (25% more)and when sampling clustered populations. Of course,

for studies of rare or endangered animals these num-bers may be unachievable, and alternative methods ofanalysis may prove more informative. In contrast tomark-recapture studies, the absolute size of the sam-ple is important for distance sampling, rather than thefraction of the population sampled.

Iverson (1978) employed distance sampling to esti-mate population size of the Turks and Caicos iguanaon Pine Cay. He established permanent transect linesthrough representative habitats in six sectors of theisland and conducted numerous surveys at varioustimes of the day over a three-year period. The perpen-dicular distance between the trail and where eachiguana was initially seen or heard (generally flushedfrom cover) was measured and iguana density calcu-lated using a classical transect model and three dis-tance formulas, two of which incorporated detectabil-ity functions. Agreement among the computationmethods was reasonable, but the classical transect cal-culations resulted in lower density estimates thanthose incorporating detectability functions.

Additional distance sampling considerationsDuring any given survey, some lizards inevitably willbe underground or hidden in vegetation, refusing toflush. Activity, and hence detectability, of iguanasvaries with time of day, season, and size and sex ofindividuals (Iverson 1979; Wiewandt 1977).Juveniles often are very secretive, so estimates mayneed to be restricted to adults (Iverson 1978). Adultmales may be more conspicuous during the matingseason when they defend territories, while adultfemales may be disproportionately under-representedsubsequent to mating and during egg-laying. Recentweather conditions may also influence iguana activity.Because an unknown proportion of animals cannot bedetected, both classical transect models and distancetechniques often underestimate true population size.

Population underestimation can be minimized byrepeated sampling at optimal times and inclusion ofdata for only the highest counts obtained, as done byIverson (1978). It is also possible to adjust estimatesif information about the percentage of animalsencountered during a given survey is available. Forexample, Hayes et al. (1995) discovered in surveys oftwo cays that only a third of marked San Salvadoriguanas were detected. Thus, they multiplied by threethe number of animals counted by classical transectson other cays where few or no animals were markedto obtain more accurate estimates. With the exceptionof one population where iguanas have since beenextirpated, estimates by Hayes et al. (1995), and evenabsolute numbers of iguanas seen, far exceeded earli-er estimates by Gicca (1980) based only on classicalline transects. Although it is possible that numbers

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actually increased during the intervening years, differ-ences between the two studies more likely reflectedthe timing of Gicca's visit during a season of loweractivity (December, 1974 versus March-July, 1994)and violation of the assumption that all animals with-in the transect were encountered.

Variation in habitat may complicate estimation oftotal population size. On larger islands, iguanas typi-cally occupy a range of habitats. To accurately esti-mate total population size, it may be necessary to con-duct distance surveys in randomly selected sites with-in each habitat and calculate population density foreach. If the island-wide distribution of each habitat isknown, population estimates for all habitats can besummed to estimate total population size (Iverson1979). For very small cays, it may even be possible tosample the entire island (Hayes et al. 1995). Criticalhabitat such as nesting areas should also be surveyedduring the appropriate season to evaluate managementneeds (Haneke 1995).

Distance sampling models assume that animals donot move prior to detection and that individual igua-nas are detected independently. This may become aproblem at higher densities, when an observer maydisturb an iguana, potentially resulting in double-counting and affecting the behavior of other nearbylizards. Obtaining distance and angle measurementsmay also make determining initial locations of ani-mals difficult when a number of iguanas are in view atonce, and bias may occur when selecting the nextfocal animal. Slow, deliberate movement can minimizedisturbance, and the departing animals may offsetthose which remain cryptic. At low densities, it maybe advantageous to occasionally leave the transect linein search of iguanas, carefully probing vegetation witha long rod to assist in detection of animals reluctant toflush (Hayes et al. 1995). More than one observer canalso be of value, as long as effort is focused close tothe transect line or central point and decreasessmoothly with distance so as not to introduce bias. Auseful approach is to have one person remain on thetransect line, while additional workers systematicallysearch for iguanas on each side of the line.

For comparative and experimental studies, stan-dardization and repeatability of sampling method,effort, and conditions during replicate surveysbecomes very important. All possible sources of bias,including sampling method, differences in habitat,iguana density, seasonal and climatic factors, andobserver experience, reliability, and technique shouldbe identified and minimized. Standardized surveysconducted on an annual basis are necessary to assesspopulation responses to adverse effects. Populationchanges need to be documented when managementchanges are implemented, including release of head-

started juveniles and habitat restoration. Comparisonsof iguana density on islands with and without intro-duced species are needed to confirm their negativeimpact. If feral animals are eradicated from infestedcays, annual surveys of juvenile to adult ratios mayindicate increased reproductive success and recruit-ment. Even indirect measures of iguana abundance,such as the density of feces or burrows or the ratio ofactive to inactive burrows can be valuable in monitor-ing conservation efforts (J. Iverson, personal commu-nication).

Information on sex or body size of iguanas sampledis helpful in assessing population structure and effec-tive population size. Even more useful informationcan obtained if animals are captured supplementary tosurveys. Measurements of body size and confirma-tion of sexual identity and reproductive condition arevaluable for learning more about population demogra-phy, including the sex ratio, individual growth rate,frequency of injuries, reproductive rate, and age ofsexual maturity (Iverson 1979).

Mark-recapture methodsMark-recapture studies involve the initial capture of arandom and representative sample of animals, whichare marked and then released back into the population.At a later time, another random sample is captured, orin some circumstances sighted, and the number of ani-mals previously marked is recorded. If certainassumptions hold, the ratio of marked animals to totalanimals in the second sample, together with theknown number of marked animals, can be used to esti-mate total population size using the Lincoln-Petersonequation: Nmarked / Ntotal = Nrecaptured / Nsampled.Multiple capture designs with varying assumptionscan be incorporated, making the approach applicableto a diversity of sampling situations that yield moreprecise and accurate estimates than two-sampledesigns. As with distance sampling, experimentalstudies for hypothesis testing are served well by mark-recapture programs (Skalski and Robson 1992).

Mark-recapture studies have several advantages forconducting population surveys. First, they can pro-vide a better estimate of population size than distancesampling techniques, which generally underestimatepopulation size. Second, repeated sampling ofmarked individuals can generate additional demo-graphic and ecological data. Finally, the proportion ofmarked animals sighted or recaptured can indicate theproportion of each sex and size class that is active dur-ing a given population survey, which in turn can behelpful in understanding biases that influence popula-tion estimation. Compared to distance sampling, theprimary drawbacks to mark-recapture studies are theircost, time demands, and labor intensity. Large num-

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bers of animals may need to be tagged, and a high pro-portion of marked animals must be resampled in orderto meet statistically acceptable standards.

Although a variety of mark-recapture models exist,the two basic classes are closed and open populationmodels. Closed population models assume that a pop-ulation does not change composition during thecourse of the study (i.e. births, deaths, immigration,and emigration are negligible) and are probably bestapplied to data collected over the short term. Becauseiguanas are not highly vagile and many are restrictedto small islands, this assumption is often met.Although violation of this assumption can become aproblem when captures are taken over a long period,allowances can be made if these rates can be mea-sured. For two-sample experiments, the Lincoln-Peterson estimator is widely employed. K-samplemodels, with many capture events, can also be used.The software program CAPTURE (Rexstad andBurnham 1991) has been widely utilized by ecologistsin recent years for the analysis of multiple-sampleclosed population models.

Open population models are designed to accommo-date animals entering and leaving the population dur-ing the course of the study. Populations may be mod-eled as completely open (both losses and gains) orpartially open (losses and no gains, or vice versa).Two of the more common models employed are theCormack and Jolly-Seber models, which can be han-dled most readily by a number of software programs(Nichols 1992). The programs SURVIV (White1983) and SURGE (Cooch et al. 1996; manual cur-rently available on the internet at: http://mendel.mbb.sfu.ca/wildberg/cmr/surge_guide.html), in particular,are extremely powerful and especially flexible for tai-loring analyses to specific field situations (Nichols1992). Assumptions of closed and open models arecompared in Table 9.

In models based on multiple capture events, com-plete capture histories must be obtained for individualiguanas. In these cases, iguanas must be marked forindividual recognition, a condition not required oftwo-sample studies. Capture histories generally con-sist of a series of Is and Os corresponding to thesequence of sampling events, the former denotingcapture and the latter indicating no capture. A statis-tical model, the choice of which depends on assump-tions about sources of variation associated with cap-ture, can be used to evaluate probabilities of capture ateach sampling event. Results can then be used to esti-mate population size and change over time. Becauserepeated sampling results in reduced sampling error,multiple-sample models can lead to greater accuracyand precision in population estimates. Although com-plex, multiple-sample techniques can be extremely

powerful in evaluating population viability and mak-ing management decisions. Further treatment of mul-tiple-sample models can be found in Bibby et al.(1992), Nichols (1992), and Skalski and Robson(1992).

Hayes et al. (1995) employed mark-recapture meth-ods to estimate population size of San Salvador igua-nas. Using color-coded beads, they marked numerousanimals captured on several offshore and inshore caysduring May, 1993 and May, 1994. Upon returning inJuly, 1994, they conducted Lincoln-Peterson esti-mates on two cays. Investigators systematically cov-ered each island, recording with the aid of binocularsall iguanas seen as either unmarked, marked, or toopoorly seen to ascertain the presence of beads. TheLincoln-Peterson equation was then used to estimatetotal population size based on well-seen animals,while the number of poorly-seen iguanas was multi-plied by the ratio of total marked iguanas to the num-ber of iguanas resighted to derive a second estimate.These two estimators were then summed to yield totalpopulation size. The proportion of iguanas in the pop-ulation encountered during these surveys was used asa multiplier to derive population estimates for otherislands visited under similar weather conditions. Theavailability of marked lizards and the small sizes ofthe cays (each treated as a single transect) made theintegration of mark-recapture and classical transectdata ideal given limited time on the cays.

Additional mark-recapture considerationsBecause so many iguana populations are confined toislands, the assumption of a closed population is oftenvalid, at least over the short term. Nevertheless, aslong as sufficient time is provided for animals to min-gle, it is good practice to minimize the intervalbetween marking and resampling to reduce the likeli-hood that marks disappear or animals die betweensampling events. Fortunately, adult iguanas are long-lived and generally have high survivorship (Iverson1979). Although difficult to fulfill, an importantassumption of closed population models is that everyanimal in the population has an equal probability ofcapture. Juveniles in particular can be hard to find,wary, and difficult to capture, making it preferable insome cases to restrict inferences to adults (Iverson1978). Differences in seasonal activity between thesexes may also influence capture rates, even amongadults. Recognition of such biases can help directcapture efforts, but it may still be necessary to derivepopulation estimates for different classes of iguanasindependently. Sampling efforts must also be distrib-uted appropriately across different habitats.

Some models assume that marking does not affectcatchability or detectability, and that subsequent sam-

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ples are random. Yet, certain marking systems mayinfluence activity or survival, or lead to bias in cap-tures, especially when animals are collected by hand.Experience with San Salvador iguanas suggests thatanimals marked with colored beads are conspicuousand more easily targeted for capture by researchers(W. Hayes and R. Carter, personal observation). Lessconspicuous marking systems such as toe-clippingcan mitigate recapture bias (J. Iverson, personal com-munication). When it is assumed that capture proba-bilities are constant for all periods, care should betaken to conduct sampling under similar weather con-ditions, using equal sampling effort. Permanence ofmarks is especially important for repeated samplingand for open models. If, however, the loss rate ofmarks is known, adjustments to models may be possi-ble. Duplicate marking systems (e.g., colored beadsand PIT tags) can provide a backup when one systemfails.

ConclusionsBefore embarking on population studies, it is impor-tant to carefully consider objectives and constraints inorder to select an appropriate technique and fielddesign. Preliminary sampling using distance methodscan provide rough information on population size andstructure which can be useful in appropriately design-ing further population surveys. The primary advan-tages to this technique are the expediency and cost-

effectiveness with which population estimates can beobtained. By comparison, mark-recapture studiesoften require specialized equipment and an extendedtime investment to capture and mark the animals,which then must be surveyed again at a later date.Whenever numerous populations must be surveyed ina limited amount of time, distance sampling is theclear method of choice. When attempting to surveyTurks and Caicos iguanas on more than 100 cayswithin a period of several months, Gerber (1996)relied on distance techniques, but nevertheless cap-tured and marked animals on many cays that can bere-surveyed in the future.

If time and resources are available to capture andobtain measurements from animals, it is of consider-able value to mark animals for future studies. Mark-recapture studies can yield reliable estimates of popu-lation size, but also offer the opportunity to extractdetailed demographic and ecological data. Recapturefrequencies can indicate the proportion of male andfemale iguanas of different size classes that are activeduring any given sampling period. Multiple samplingdesigns yield by far the most information about popu-lation viability, potentially providing data on popula-tion changes, growth rates, frequency of injuries,reproductive rate, age of sexual maturation, mortalityrates, survivorship, and longevity.

Both distance sampling and mark-recapture areexcellent for comparative or experimental studies

Table 7. Primary advantages and disadvantages to use of classical transect, distance sampling, and mark-recapture techniques for estimation of population density, population size, or rate of population change.

Methods

Classical Transect(counts within aprescribed area)

Distance Sampling(measurements ofdistances)

Mark-Recapture

Advantages

Ideal if all animals in sampled areacan in fact be detected; useful forexperimental studies to test hypothe-ses if carefully standardized; expedi-ent and cost-effective.

Yields more reliable results for popu-lation estimation than classical tran-sects; ideal for experimental studies;expedient and cost-effective.

Can yield the most reliable popula-tion estimates; yields abundance ofadditional demographic information;ideal for experimental studies.

Disadvantages

Assumes that all animals in areasampled are detected, which is rarelyrealistic; nearly always underesti-mates population density and size;less precise than distance sampling.

Nearly always underestimates popu-lation density and size; yields mini-mal information on populationdemographics compared to mark-recapture methods.

Costly and time-consuming to con-duct; large sample sizes needed; highproportion of marked animals needto be recaptured or resighted in sec-ond and subsequent samples.

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associated with hypothesis testing, such as assessingiguana density across gradients, in different habitats,over time, or following experimental manipulation.Multiple standardized surveys can be carried outunder similar field conditions to yield strong inferen-tial data. Clearly, both transect and mark-recapturetechniques can be extremely useful for analysis ofiguana populations. Although one may be more suit-able than the other in answering a particular question,the combined use of both approaches should beattempted whenever possible to derive maximuminformation from remaining iguana populations.

While publicizing the status of highly endangered

species can be essential to raising the funds andawareness important for assembling recovery pro-grams, such publicity can arouse the murkier interestsof poachers and others who may wish to exploit thesituation. A further dilemma can arise when popula-tion surveys suggest that a species or population existsin greater numbers than previously believed. Integrityin reporting becomes an issue, especially when adowngrading from endangered status could jeopardizesupport for research and conservation programs.There are no easy answers to questions raised by theseconcerns, but they certainly need to be addressed bythe conservation community.

Table 8. Key assumptions of classical transect and distance sampling techniques.

Assumption

1.2.3.4.5.6.7.8.

All animals in transect area are detectedAll animals exactly on transect line or point are detectedEntire size of sample area is knownAnimal distances from transect line or point are accurateAnimals do not move before detectionIndividuals are counted only onceIndividuals behave and therefore are detected independentlyBias (from observers, seasons, weather) is understood

ClassicalTransect

XXX

XXXX

DistanceSampling

X

XXXXX

Table 9. Key assumptions of mark-recapture studies for closed or open population models. Parentheses indi-cate that relaxation of assumptions is permitted in certain models. After Bibby et al. (1992).

Assumption

1.

2.

3.4.5.6.7.

8.9.10.11.

Closed population (unless immigration and emigration ratesare known)Every animal in population has equal probability of capture infirst samplingMarking does not affect catchability/detectabilitySecond (subsequent) sample(s) are randomMarks are permanentCapture/sighting probability constant for all time periodsEvery animal in population has same probability ofrecapture/resighting in all sampling effortsEvery marked animal has equal probability of survivalSampling time is briefLosses from emigration and death are permanentPopulation closed to recruitment only

ClosedModels

X

XX

(X)(X)(X)

OpenModels

X

XXX

(X)(X)

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Control of Introduced Species

By Peter J. Tolson

IntroductionOne of the most serious consequences of human colo-nization of previously undisturbed habitats is the hostof exotic species which usually accompanies settle-ment. In the West Indies, introduced exotic mammalsinclude the black or roof rat (Rattus rattus), theNorway rat (Rattus norvegicus), the Indian mongoose(Herpestes javanicus [=auropunctatus]), the feralhouse cat (Felis catus), the domestic dog (Canis famil-iaris), the European pig (Sus scrofa), and the feralgoat (Capra hircus). Each of these animals directlythreatens wild iguanas at some stage of the life cycle,and some constitute a significant threat at every stage.

It must be realized that there is a wide gap betweenshort-term control and complete eradication of exoticspecies from an area. In order for reduction of popu-lations of exotics to have a positive long-term effecton iguana populations, either complete eradication orperpetual control programs are necessary. Eradicationprograms are most likely to be successful on smallislands (< 20ha), where some other stressor, such aslack of standing water, is also present. Control pro-grams can thus be initiated when population numbersare at a natural low. For example, lower levels of foodavailability during the dry season increase the chancesof an exotic consuming a poisoned bait.

Many managers of island ecosystems have had todeal with the problems of introduced predators. Themost successful outcomes have been the result of afully integrated predator management strategy whichutilized a variety of control options. These are usual-ly a combination of four basic methods: shooting,poisoning, trapping, and disease. There are alwayssome animals in a target population which will begun-shy, trap-shy, bait-shy, or poison and diseaseresistant. Thus, managers must use every means attheir disposal to reduce or eliminate the target species.The efficacy of each of these methods varies with thetarget species and the site at which control is beingattempted.

A common fault of unsuccessful exotic animal con-trol programs is the failure to realize the extent ofcommitment, both in manpower and financialresources, necessary to eliminate a target species.Removal of any exotic from an ecosystem is a difficultand time-consuming task, requiring relentless atten-tion to detail. In a typical shooting or trapping effort,the last few animals require the most effort to remove,as contact decreases in proportion to population size.In addition, the remaining animals may have devel-

oped an aversion to any type of human activity, mak-ing shooting, trapping, and poisoning much more dif-ficult than they were initially.

It is also an inescapable fact that any exotic animalcontrol program will face stiff opposition from someelements of society, and managers may find that them-selves confronted with a well-organized, well-fundedadversary that is inalterably opposed to any killing ofany animal species for any reason, even if the failureto eradicate that species means the death of an entireecosystem. The best basis for defense of any controlprogram for exotics is a well-defined plan thatabsolutely minimizes any danger to humans or non-target species.

Advantages and disadvantages ofvarious control optionsTrapping. Trapping does not require constant effort,but may require considerable expense in setting up thetrapline due to the need to clear vegetation for trails,transects, or grids. Live traps are often heavy andbulky, and thus are difficult to transport to interiorareas where roads or trails are not available. Trappinghas the major disadvantage of putting non-targetspecies in peril. Trapping in an area populated byiguanas would have to be performed at night, with setsprepared just before dark, and traps disabled beforedaylight. Trapping under these conditions would beineffective for diurnal predators such as dogs andmongooses, but could be very effective for cats.Attempts to trap larger animals such as feral pigs andgoats are generally not cost-effective.

Shooting. Shooting can be a very effective form ofcontrol when the target species is large and there isminimal vegetative cover. It is most useful when therehas been no previous history of hunting in the targetarea, and when there is no human habitation of the tar-get area. It is generally low-cost in terms of equip-ment expenditures, but requires a very heavy man-power commitment. It is less effective at night.

Poisoning. Poisoning can be an effective form ofcontrol for certain exotic predators, especially as anadjunct to trapping. However, poisons are not free ofdisadvantages. Many poisons are toxic to fish, birds,other wildlife, and domestic animals, and pose a sec-ondary hazard to birds of prey and carnivorous mam-mals. Carelessly placed baits could potentially beconsumed by iguanas. Accidental poisonings can beavoided by used of bait boxes with small entry holesthat exclude iguanas. Because of their hazardousnature, some poisons may be controlled by federal orlocal use restrictions, and may require permits for use.

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Disease. Introduction of pathogens or parasites canbe useful in reducing host fecundity and loweringpopulation density of exotic species. However, suchprograms by themselves are unlikely to completelyeradicate host populations. The major concern withthis type of control program is that populations ofendemic species may become infected. To ensure thatthis does not occur, it is important to choose a highlyspecific pathogen (Dobson 1988).

Black and Norway ratsThe black rat is one of the most destructive introducedpredators in the West Indies. Its invasion of theGreater Antilles probably began with its introductionto Hispaniola following the wreck of the Santa Mariaat La Navidad in 1493, and it has continued to spreadsince then (Allen 1911; Atkinson 1985). Atkinson(1985) documented the invasion of western Europe bythe Norway rat in the early 1700s. As a result, theNorway rat became the dominant rat in Europeanports, and thus the most common ship rat on sailingships of that era. Between 1700 and 1830, Norwayrats successfully invaded many islands.

Rats are extremely adaptable in their food prefer-ences, can exist for long periods without water, andhave an exceptionally high reproductive rate.Although approximately 95% of the diet consists ofplant material, they are known to prey on invertebrates(Strecker et al. 1962), amphibians and reptiles(Whitaker 1978), and birds (Austin 1948; Atkinson1985; Johnstone 1985). Rats pose an extreme hazardto many endangered species in the West Indies.Because Norway rats are significantly larger and moreterrestrial than black rats, they potentially pose a moreserious threat to iguana nests. However, Norway ratsare far more common in urban and suburban areas,whereas outlying cays are almost exclusively populat-ed by black rats. D. Nellis (personal communication)has evidence that the mongoose, a terrestrial predator,may effectively exclude Norway rats from naturalareas in the Virgin Islands. Although many naturalpredators such as raptors and the West Indian boasprey on rats, the rate of reproduction for rats is so highthat population numbers easily keep pace with anylosses to predation. This has led to several pastattempts to control rats, many of which have failedbecause of high rat immigration rates and lack of ade-quate resources and commitment.

The most effective poisons currently used todayto control rats are the anticoagulant compounds suchas brodifacoum and bromadiolone. The active ingre-dients are imbedded in a paraffin matrix which is rel-atively impervious to weather. Ten gram blocks ofpoison are easily carried and distributed, remain palat-able for long periods, and do not cause bait-shyness.

Rats may consume a lethal dose in one feeding. Themost successful rat poisoning attempts are those car-ried out during the dry season, when foods such asfruits, buds, and tender leaves are at a minimum. Forcomplete eradication, three applications of poison of5-10 blocks per interstice on a 10m x 10m grid spacedsix months apart are recommended. Heavier applica-tions can be made in areas which show the greatestamount of rat activity, such as rock piles and tree-rootwarrens. Grids need to be examined every day forthree to seven days and poison replaced as it disap-pears. Use of bait boxes with small entry holes areimportant to reduce the risk to non-target species.One of the greatest problems of application is con-sumption of bait by insects and other invertebrates,particularly hermit crabs. There seems to be no prob-lem with toxicity to these species, but they can rapid-ly deplete a bait placement. Consumption of bait byinvertebrates can be reduced by anchoring the bait totrees approximately one meter above the ground.

Trapping is also often used to reduce rat popula-tions, but usually in conjunction with poisons if com-plete eradication is the goal. Certain individuals arecompletely trap-shy and will not be captured usingtrapping methods. In addition, a significant number ofrats escape from traps and in all probability will not betrapped again. More effective trapping can often beaccomplished by minimizing human scent around thetrap site through application of urine-soaked domesticrat bedding and use of rubber gloves when setting traps.

Indian mongoosesUrich (1914) reports that most of the mongooses inthe New World are descended from 5.4 animalsimported from Calcutta to Jamaica by Espuet in 1872to combat black rats. From there, mongooses werereleased onto the remaining Greater Antilles. In lessthan 30 years, all West Indian islands supporting asugar industry had introduced mongoose populationsderived from these original sources (Nellis andEverard 1983).

Despite initial effectiveness in rat control, depreda-tions of mongooses soon expanded to include severalspecies of ground nesting birds, endemic snakes, andterrestrial lizards, including iguanas. Because of theirsmall size, mongooses are not considered a majorthreat to adult iguanas. However, mongooses certain-ly have the ability to kill and eat juveniles, and theymay enter nest emergence holes and eat full-termembryos in the egg. In Jamaica, 12 to 17 years afterthe mongoose was introduced to the Goat Islands,there were only five iguanas left (estimated decreaseof 29-38% per year). The efficiency of the mongooseas a diurnal, terrestrial predator in the West Indies isunsurpassed.

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Setting traps for the Indian mongoose controlprogram in the Hellshire Hills, Jamaica.

Mongooses are readily trapped in box traps. Nellisand Everard (1983) used Tomahawk live traps baitedwith pork liver to capture mongooses on St. Croix,U.S. Virgin Islands. An eradication program initiatedon nearby Buck Island by the National Park Serviceused live traps baited with chicken meat to eliminatethe mongoose population. The entire island was grid-ed with transect lines and traps were placed every 50mon the grid. Although mongooses are susceptible topoisoning with diphinacinone, bait delivery wouldhave to be accomplished with an exclusionary devicesuch that iguanas would not be at risk. Shooting isineffective due to the small size and speed of mon-gooses. Mongooses are apparently sensitive to caninedistemper, but the extent to which this would repre-sent a viable control option is unknown.

Feral house catsHouse cats were probably introduced to the WestIndies shortly after discovery by Europeans. Ashuman habitation of an area increases, greater num-bers of cats arrive, mostly brought in initially as housepets. Because they can be extremely efficient diurnalpredators, house cats pose a severe threat to hatchlingiguanas. The following program serves as an exampleof how difficult cats can be to eradicate. A four-yeareradication project for cats was carried out from 1977to 1980 on Little Barrier Island, New Zealand. Theproject involved 128 people, and over 950 leg-holdtraps and 27,000 poisoned baits were used. One hun-dred sixty one cats were known to have been killed(Rauzon 1985;Veitch 1985).

Although cats may be poisoned using a compoundsuch as sodium fluoroacetate (1080), the extreme dan-ger of this compound, particularly the risk of sec-ondary poisoning, is so great that its use is restrictedto professional operators, and it poses a clear risk toiguanas. Trapping appears to be a better alternative,

and leg-hold trapping in particular is very effective forcats (Veitch 1985). Because they are padded, theVictor Soft Catch coil spring traps are more humanethan conventional leg-hold traps. Baited Havahart orTomahawk box traps may also be used, but are inferi-or to leg-hold traps. If box traps must be used, dou-ble-door cage traps with two open ends are preferred,as cats are normally reluctant to enter closed spaces.Trapping success will be enhanced if every attempt ismade to minimize human scent at the trap site.Shooting is another potential control option for feralcats. At, night a good light source will illuminate thetapetum and create an eyeshine that will aid in loca-tion of cats (Rauzon 1985). Finally, feline panleuco-paenia virus (FPL) has been used effectively in con-trolling (not eradicating) cat populations on severalsub-Antarctic islands such as Marion Island (SouthAfrica), Macquarie Island (New Zealand), and JarvisIsland in the Pacific (Johnstone 1985; Rauzon 1985;Rensberg et al. 1987).

Domestic dogsFeral dogs represent one of the earliest invaders of theWest Indies, as virtually all Spanish expeditionaryforces had them (Las Casas 1552). Dogs pose themost severe threat to adult iguanas, particularly nest-ing females. Iverson (1978) reported reduction of apopulation of Turks and Caicos iguanas on Pine Cayfrom 5,500 to a very few individuals after the intro-duction of a small number of dogs and cats to theisland by a hotel construction crew.

Control of domestic dogs may best be accom-plished by preventing owners from bringing their dogsinto areas inhabited by iguanas. Personal contactbetween researchers, managers, and local forest usersis essential in this regard. Shooting, which has beenextensively used in coyote control programs in thewestern United States, may be the most effectiveoption for feral dogs. Trapping of dogs with leg-holdtraps is also very effective. However, because thediurnal activity of dogs corresponds to that of iguanas,traps would pose a considerable risk of injury to igua-nas. As with feral cats, the risk to non-target animalsprecludes poisoning as a viable control option.

European pigsPigs were often liberated on small islands throughoutthe West Indies to serve as a food source for ship-wrecked sailors. Pigs are primarily a threat to iguananests. Pigs locate nests by smell, making nests mostvulnerable in the three to four days following eggdeposition by females. After this period, the iguanascent surrounding the nest dissipates, and pigs aremuch less likely to detect nests. Because pigs foragein groups, discovery of a densely-utilized communal

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nesting area could result in the destruction of a signif-icant number of iguana nests.

Pig predation can be effectively controlled by con-struction of exclosure fencing around nesting areas, ashas been done on Mona Island, Puerto Rico. Densityof pigs can also be reduced by shooting, but this canbe dangerous, as wounded animals will often turn andattack. Pigs are most easily hunted with dogs, but ifthis strategy is adopted only neutered males andspayed females should be used to prevent establish-ment of feral dog packs.

Feral goatsGoats were introduced to island ecosystems byEuropean man, probably early in the 16th century. Aswith pigs, they were often liberated on small islandsof the West Indies to serve as a food source for ship-wrecked sailors. Feral goats are notorious for habitatdestruction and extirpation of endemic plants onoceanic islands (Coblentz 1978; McFarland 1991).Forest destruction by goats has been implicated in thedisappearance of many species, from Hawaiian hon-eycreepers (Baker and Reeser 1972) to snakes(Coblentz 1978). Wiewandt (1977) considered goatsto be a major competitor of Mona Island iguanas,removing high quality herbaceous iguana forage byoverbrowsing. Goats have been shown to increaseavian predation on juvenile Galapagos land iguanas(genus Conolophus) by overbrowsing and the subse-quent loss of vegetative cover (Dowling 1964).

Although expensive, goat browsing can be con-trolled by construction of exclosure fencing. Suchfencing must be at least 2m in height. Shooting ofgoats is probably the most effective means of control.Goats tend to congregate in sleeping areas at nightwhere they can be ambushed. Use of bells on trappedand released "Judas goats" may be useful in locatingthe herd (Keegan et al. 1994). Finally, the protozoanTrichomonas foetus has been suggested as a potential-ly useful control agent for feral goats (Dobson 1988).Because this is a sexually transmitted disease, the riskthat endemic species will accidentally become infect-ed is greatly reduced.

Genetic Research Needs

By Scott Davis

Genetic research should address four major issues fac-ing conservation efforts for West Indian iguanas: 1)genetic distinctiveness and taxonomic status ofspecies, subspecies, and populations, 2) hybridizationof genetically distinct species or subspecies in captive

and natural populations, 3) pedigree relationshipsamong individuals used in breeding programs andreintroduction efforts, and 4) retention of genetic vari-ation during long-term management of small WestIndian iguana populations.

Given the limited resources available for conserva-tion of West Indian Iguanas, it is important that anyrecommended conservation actions are based on accu-rate taxonomy. At present, most island populations ofrock iguanas are recognized as distinct species or sub-species, but there are only limited genetic data to sup-port this classification. Based on the experiences ofresearchers in other groups, it seems likely that agenetic survey of rock iguanas will identify uniquegenetic entities (species or subspecies) that are cur-rently unrecognized. It may also point to significantgenetic differentiation between conspecific rock igua-na populations on some of the larger islands (e.g.,Cuba). Finally, such a survey may identify subspeciesof rock iguanas that are not genetically distinct andthus not deserving of their current taxonomic status.In combination, these findings would allow futureconservation action to focus on preserving the uniquegene pools within the genus. A sequence study basedon mitochondrial DNA of all extant species, sub-species, and populations of rock iguanas is currentlyunderway at Texas A & M University.

As species become rare, it is common for problemswith hybridization to occur. The subspecies ofCyclura nubila provide a classic example of theimpact of hybridization on conservation efforts. TheGrand Cayman iguana has been under intense pres-sure by man through the alteration of habitat andintroduction of feral predators. One of the largestrock iguanas, the Grand Cayman iguana occurs onlyon Grand Cayman (Grant 1940). Two other sub-species, the Cuban iguana and the Lesser Caymansiguana are also recognized, with their ancient distrib-ution limited to Cuba and the Isla de Pinos, and LittleCayman and Cayman Brac, respectively (Schwartzand Carey 1977).

In 1990, the Lizard Advisory Group of theAmerican Zoo and Aquarium Association (AZA) des-ignated the Grand Cayman iguana as a high priorityfor conservation and captive management. Althoughthis subspecies represented an excellent candidate forintensive captive breeding, two problems complicatedimplementation of a managed breeding program.First, reports of recent introductions of LesserCaymans iguanas onto Grand Cayman raised the pos-sibility that subspecific hybridization had occurred innature (Schwartz and Carey 1977). Second, concernexisted among the zoo community that some of thefounders of the existing captive population may havebeen hybrids of Lesser Caymans iguanas and Grand

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Cayman iguanas. Obviously, the existence of subspe-cific hybridization within the population would createproblems for efforts to conserve the genetic purity ofthis taxon.

Life Fellowship Sanctuary (Seffner, Florida) pro-duced all of the founding stock of captive bred GrandCayman iguanas, which were dispersed to severalzoos and returned to the Cayman Islands. The LifeFellowship group was founded with five males andtwo females imported from the Cayman Islands andan additional female and two of her offspring pur-chased from a Florida herpetologist in 1987 and 1984,respectively. Unfortunately, the two offspring pur-chased in 1984 may have been produced using a maleLesser Caymans iguana, and would thus be hybrids.In addition, the female parent of these potentialhybrids was herself of unknown origin. These threequestionable animals had made a significant contribu-tion to the captive population; thus many of the ani-mals under consideration for a managed program anddestined for release in the wild were potentially ofhybrid origin. The American Zoo and AquariumAssocation's Lizard Advisory Group decided to pro-ceed by authorizing a genetic study on the existingbreeding stock.

Genetic data collected at Texas A & M Universitydemonstrated that the questionable female was ofhybrid origin (probably from a male Grand Caymaniguana and a female Lesser Caymans iguana) and thusher offspring and approximately 50% of the existingcaptive population, including animals returned toGrand Cayman for captive breeding, were of hybrid

origin. The hybrids have now been removed from theprogram, but the problems with this iguana point outthe importance of collecting genetic data as early aspossible.

Reports of an introduction of Lesser Caymansiguanas into the wild population of Grand Caymaniguanas were apparently unfounded. However, genet-ic data from the remaining wild Grand Cayman igua-nas will provide an unequivocal answer. For mostspecies of West Indian iguanas, a very real possibilityof human translocation exists.

Another use for genetic data is the clarification ofrelationships among founders of captive breeding pro-grams in order to maximize retention of genetic vari-ation and minimize problems due to inbreedingdepression. An example of the need for such data isprovided by the Jamaican iguana. The Hope Zoo inKingston, Jamaica, in collaboration with the AZALizard Advisory Group, began a headstart program forthis species with over 100 individuals collected fromclutches laid by wild females between 1991 and 1994.Without genetic data it was impossible to ascertain thenumber of wild founders represented. If each wildclutch was produced by a different pair, there could be30 or more founders, but in the worst case, all off-spring could have been the product of three femalesbred by a single male.

To evaluate this situation, lml of blood was drawnfrom the caudal vein (Esra et al. 1975; Gorzula et al.

Lateral entry technique for collecting bloodsamples from the caudal vein of iguanas.

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Ventral entry technique for collecting bloodsamples from the caudal vein of iguanas.

1976) of each of the hatchlings, and, where possible,from egg-laying females. A genetic analysis of theDNA in these blood samples using microsatellitemarkers allowed the characterization of both maternaland paternal genetic contributions. Genetic inputfrom at least two male and four female founders wasdocumented and this information was used in select-ing founders for the captive breeding program thatwould maximize initial genetic diversity and avoidinbreeding. Similar analyses would benefit captivebreeding programs for other West Indian iguanas.

Genetic research depends on the availability ofmarker systems, a variety of which have been used forgenetic analyses of vertebrate populations, includingprotein electrophoresis, karyotyping, mitochondrialDNA restriction fragment length polymorphisms, andDNA fingerprinting. In recent years, two techniqueshave emerged as ideal tools for genetic analyses ofpopulations: mitochondrial DNA sequences andnuclear DNA microsatellites. Both of these tech-niques provide high level resolution and both arebased on the polymerase chain reaction (PCR). PCRtechnology offers the tremendous advantage of utiliz-ing only minute amounts of sample and of providingdata even when available samples are of very poorquality (such as museum specimens or shed skins).Mitochondrial DNA is a maternally inherited markerand microsatellites are nuclear, biparentally inheritedmarkers. Microsatellites are similar to DNA finger-

prints but are single locus, co-dominant, Mendelianmarkers and are therefore much easier to interpret inpedigrees. In combination, mtDNA allows the identi-fication of unique maternal lineages and reconstruc-tion of evolutionary relationships, while microsatel-lites allow the characterization of both maternal andpaternal contributions to the gene pool. Both markersystems are in place for rock iguanas, and all that isneeded arc samples from the appropriate animals.

Captive Management Guidelines:Cyclura

By Bill Christie

Captive programs are currently in place for five taxaof rock iguanas. In addition to the captive rearingprogram at the Hope Zoo in Jamaica, a satellite pro-gram for Jamaican iguanas in the U.S. has recentlybeen instituted, with 2.2 individuals each at the FortWorth and Gladys Porter zoos, 1.2 individuals each atthe Indianapolis, Central Florida, and SedgwickCounty Zoos, and 3.3 individuals at the San DiegoZoo's Center for Reproduction of EndangeredSpecies. In collaboration with the National Trust forthe Cayman Islands, a program for the Grand Caymaniguana is also currently underway, involving animalsat the Bermuda Aquarium, the John G. SheddAquarium, and the Indianapolis, Central Florida, andBurnett Park Zoos. North American captive popula-tions of both taxa will be managed under theAmerican Zoo and Aquarium Association's first lizardSpecies Survival Plan. A small number of Ricord'siguanas (1.3) at the Indianapolis Zoo are being man-aged as part of a cooperative program with Zoodom inthe Dominican Republic. Although Cuban iguanasand rhinoceros iguanas arc widely held in NorthAmerican collections, the primary purpose of theseprograms is for research and education rather thancaptive breeding.

HousingRock iguanas are large lizards that need a fair amountof space devoted to them as adults. A minimum of10m- is recommended for an adult pair. This spacecoupled with several visual barriers allows adequateroom and minimizes territorial aggression. Rockiguanas can be kept in groups if enough space is pro-vided, although they are very territorial and a domi-nance hierarchy will quickly emerge. With the excep-tion of Ricord's and rhinoceros iguanas, which arenaturally sympatric, the other species of rock iguanasshould remain separated. Equally important to the

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Cork bark tubes provide hide areas for juvenileiguanas at the Hope Zoo, Kingston, Jamaica.

housing arrangement are secure hide areas to whicheach animal has exclusive access. They may not eachuse a separate hide, but it is important that it be avail-able. They will use these hides to escape conspecificaggression and to retire for the evening.

Ideally, iguanas should be housed outdoors, therebyproviding access to natural sunlight. Year-round out-door maintenance is preferable, with attached, heated,indoor holding for cooler periods. Care must be takento prevent the iguanas from digging out of the enclo-sure. A 2.5cm x 2.5cm wire mesh is adequate for con-tainment. A natural substrate of sand, gravel, turf or amixture of these components is preferable. If breed-ing is expected, then a nest area with adequatedrainage is required. As large an area as possibleshould be provided as female rock iguanas can digextensive nest tunnels and chambers.

Successful maintenance of rock iguanas can beaccomplished in temperate climates through move-ment outdoors in warm summer months. Althoughmoving the animals in this way has been successfulfor maintaining and even breeding some species ofrock iguanas, this method may be too stressful forlong term reproduction programs. Moving animals

during critical breeding or egg-laying periods shouldbe avoided. Rock iguanas can be maintained indoors,providing that all the above parameters are met.Accessible artificial UV light within 50cm above abasking site should be provided. Temperature gradi-ents within iguana enclosures should range up to40°C.

NutritionRock iguanas are primarily herbivorous. Captivespecimens maintained properly will feed on a widevariety of fruits, vegetables, leafy greens as well asvarious sources of protein. Dry, leafy, alfalfa hay maybe accepted by some rock iguanas as browse. The ani-mal protein component should make up only about5% of the diet. Some juveniles will feed readily oninsects and may have larger percentages of protein intheir diet. As adults, rock iguanas seem to be oppor-tunistic predators and will readily take meat if offered.Food should be offered to these browsers daily,although care must be taken to prevent obesity.Providing a varied diet is important and use of sea-sonally available produce helps maintain a lively feed-ing response. The addition of a powdered multivita-min and a calcium source two to three times weekly isrecommended. Although they are rarely observeddrinking, rock iguanas should have access to a watersource.

HealthRock iguanas are extremely healthy, long-lived ani-mals when cared for properly. Endoparasites can beeasily treated with various anti-helminthic agents, towhich the animals generally respond very well.Ectoparasites can be treated by standard methods.Conspecific aggression can result in physical injuriesto iguanas. Although these are usually minor scrapesor cuts, occasionally more serious injuries resultwhich require suturing and antibiotic treatment.

BreedingSeveral species of rock iguanas have bred successful-ly in captivity, particularly rhinoceros and Cubaniguanas. Successful reproduction can occur with sin-gle, adult pairs in an enclosure. Combat behaviorcould be an important stimulus for reluctant males,and if space allows, rock iguanas should grouped toallow for pair bonding and male combat. In captivity,rock iguanas are annual, seasonal breeders. Breedingusually takes place in the spring or summer, andhatching in the fall. A fluctuating photoperiod seemsto have a dominating influence on the reproductivecycle.

Impending egg laying is preceded by an arrestedappetite and excessive activity by the female. Gravid

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females will dig several test nests searching for anappropriate place to lay. It is important that a suitablenesting area is provided to the female. If not, she mayretain the eggs longer than desired, which could causelow hatching success and/or health problems.

If the conditions are appropriate in the enclosure,eggs can be left where they were laid for incubation.If the nest chamber can be located, which can be dif-ficult in large nesting areas, it is probably better toremove the eggs for artificial incubation. Rock iguanaeggs are large and require adequate oxygen andhumidity. Several incubation media, including sand,peat moss, vermiculite, or various mixtures of these,have been used with good success. A temperature of30°C results in high hatching success and healthy, fer-tilized eggs will hatch in 80 to 100 days.

Care of neonates should be similar to that of adults.although extra precautions should be taken to ensureadequate hydration. With enough space, juveniles canbe raised together. Some species may show more con-specific aggression than others, and this needs to bewatched closely to ensure that severe problems do notarise. Diet can be similar to that of the adults. Moreanimal protein is preferred by some species, whereasothers may virtually ignore insects. Well cared forhatchlings can grow quickly and require substantialspace to mature adequately.

Eggs of the Lesser Caymans iguana.

Captive Management Guidelines:Iguana delicatissima

By Steve Reichling

The Lesser Antillean iguana is currently held at threeinstitutions: Jersey Wildlife Preservation Trust (1.1.1),the Memphis Zoo (2.2), and the San Diego Zoo'sCenter for Reproduction of Endangered Species (1.1).All eight adult specimens are potential founders, col-lected on Dominica. All of the specimens are on loanfrom the Ministry of Agriculture (Division ofForestry) of the Commonwealth of Dominica, andtransfers or movement of adults or offspring betweencollections can only be done with the Ministry's priorauthorization.

The only U.S. Zoo having past experience in main-taining this species is the Philadelphia Zoo, whichkept specimens collected by J. Lazell during the late1950s. A private collector in Europe, L. Wijffels, haskept Lesser Antillean iguanas but reported that hisspecimens fared poorly, being very shy and reticent tofeed. This fragility in captivity, at least with regard towild caught specimens, appears to be a consistenttrait. The recent acquisition of specimens by zoos hasbegun to shed more light on husbandry parametersappropriate for this species.

In general, basic husbandry parameters applicableto rock iguanas and common iguanas, which are well-documented in the literature, are appropriate forLesser Antillean iguanas. The information belowfocuses on management considerations in which theLesser Antillean iguana differs from most other WestIndian iguanas.

HousingLarge enclosures seem to be important. The twoJersey specimens live in an area measuring 3m high x4m wide x 3m deep, those at Memphis are maintainedin a 6m x 8m x 3m enclosure, and those at San Diegoin a 4m x 4m x 8m enclosure. Height is critical forproviding security to the lizards, at least for the high-ly arboreal individuals from Dominica. Keepers canenter the cage without disturbing the iguanas as longas the enclosure is high enough to allow the lizards toroost well above intruders. When Lesser Antilleaniguanas are kept in a cage too small or short to allowhigh roosting, the iguanas remain stressed and panic atthe slightest disturbance. Equally important for cagesecurity is the provision of adequate plantings andclimbing surfaces. M. Day reports that in Dominica,Lesser Antillean iguanas rarely come to the ground,and instead move from tree to tree by way of inter-locking branches in the canopy. In captivity, a fewbare branches do not provide adequate tactile and

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Lesser Antillean iguana enclosure at the Centerfor Reproduction of Endangered Species, SanDiego Zoo.

visual security for Lesser Antillean iguanas. TheJersey, Memphis, and San Diego enclosures are heav-ily planted with tall, tree-like vegetation, such asbanana, Ficus, and large Hibiscus. It is possible thatthese parameters may not be as important for speci-mens originating from more xeric islands.

In Dominica, female Lesser Antillean iguanas exca-vate deep burrows prior to oviposition (M. Day, per-sonal communication). This fact, coupled with theobservation that most egg-laying in captivity spansseveral days, with eggs scattered throughout enclo-sures, suggests that adequate nesting sites with deepsubstrate may be necessary to elicit normal nestingbehavior and oviposition in captives.

As for Cyclura, high intensity, full-spectrum illu-mination is essential for the successful captive main-tenance of Lesser Antillean iguanas. This can be pro-vided naturally in outdoor enclosures or via UV-trans-mitting skylights, or artificially with a combination offull-spectrum fluorescent tubes and metal halidelamps. Temperatures suitable for rock iguanas areappropriate for this species as well.

NutritionWild-caught specimens are extremely particular in thefoods they will accept. Favored items include sweetpotato leaves, fresh figs, Opuntia fruit, papaya, grapes

(especially red and black), and fresh whole cranber-ries. These are the best foods to offer freshly capturedspecimens. With patience and persistence, they willgradually begin to accept a wider variety of fruits andleaves. Captives have taken plums, lettuce, mango,cabbage, kale, collared greens, dandelion, orange,apple, banana, pineapple, and cherimoya. Many ofthese items are not accepted until the lizards are well-acclimated and routinely feeding on their preferreditems. Unquestionably the best item to offer new cap-tives is sweet potato leaves, made available by placingpotted plants in the enclosure and allowing the lizardsto graze naturally. This is usually the first, and some-times only, food item that freshly imported captiveswill accept. Hibiscus (young leaves and red blos-soms) and Ficus benjamina are also grazed. The foodpreferences of captive-born Lesser Antillean iguanas,once they become available, may prove less limited.

The native diet seems to consist almost exclusivelyof young vines and leaves, with some fruit in season.Field research by M. Day has included fecal analysisand stomach content studies using road-killed individ-uals. Results of his studies will be invaluable to bet-ter assess the suitability of the items offered to cap-tives, and to refine the diet. Data available thus farsuggest that limiting the amount of fruit may be advis-able. Lazell (1973) reported observing specimens onLa Desirade consuming bird eggs, carrion andOpuntia fruit, and induced semi-captives on Dominicato accept a variety of fruit, but noted that citrus andpapaya were consistently ignored.

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HealthSpecimens on St. Eustatius were observed to harborsmall, red mites on the head and around the eyes.Fecal examination of wild-caught specimens fromDominica revealed heavy burdens of strongyles andoxyurids, which were eliminated after three doses offenbendazole (administered orally, 100mg/kg bodyweight) spaced two weeks apart. Necropsy results ofa female housed at Memphis revealed Salmonella sp.,although whether this was a contributing factor to thedeath of the specimen remains speculative.

BreedingThe first captive breeding of Lesser Antillean iguanasoccurred on 20 May 1997, when a single egg pippedat the Jersey Wildlife Preservation Trust. No othereggs in the clutch survived. Eggs were incubated at31°C for 73 days, on a 1:1 water to vermiculite sub-strate. The hatchling weighed 20g and had an SVL of75mm (R. Gibson, personal communication).Oviposition has occurred at all three participatinginstitutions, and copulations have been confirmed atJersey and Memphis. In Memphis, breeding takesplace in March, and eggs are laid in May and June.Except for the single viable egg at Jersey, all eggshave failed to hatch despite the fact that many wereconfirmed fertile. Because all captive specimens areowned by the government of Dominica, the expansionof the captive population and the placement of surplusanimals will require consultation with and approval bythe Dominican Ministry of Agriculture.

Education and Ecotourism

By Allison Alberts

Local community programsDevelopment of in situ education programs for WestIndian iguanas should form an essential cornerstoneof any efforts devoted to their conservation. First, it isimperative to educate local people living in areaswhere they will have direct contact with free-rangingiguanas. This is especially important when iguanashave been reintroduced to previously unoccupiedhabitats where the community may be unfamiliar withthese animals and their habits. Schools are probablyan ideal place to start, as young people are much lessprone to have preconceived notions about localwildlife and may be especially likely to share theirenthusiasm for preserving it with other family mem-bers. Videos, slideshows, educational brochures, andposters can all serve as effective means for spreadinginformation about iguanas and their conservation

Jamaican nationals displaying a "Save theJamaican iguana" poster at the Hope Zoo inKingston.

needs throughout the community and beyond. Thehigh quality poster depicting the plight of theJamaican iguana produced in conjunction with thePHVA workshop for this species (CBSG 1993) hasbeen instrumental in raising funds for conservation. Atthe national level, commemorative stamps and coinscan be useful in making the general public aware ofthe endemic flora and fauna inhabiting their islands.

Although education programs should probably befocused initially on localized areas of high iguanaconcentration, eventually they could be expanded toinclude surrounding areas. Even people having onlyoccasional contact with iguanas need to be alerted asto their protected status and encouraged to immedi-ately report any violations of regulations to localauthorities. On some cays in the Bahamas, prominentsigning of nesting areas has been helpful in keepingdisturbance of gravid females and hatching young byvisiting tourists to a minimum.

Because iguanas are large, photogenic, and charis-matic, they have the potential to serve as flagshipspecies for promoting conservation of the dry tropicalforest ecosystems they inhabit. Many of these rem-nant forests represent the last refuge for a variety ofother species, including many endemic plants. InCosta Rica and Panama, integrated management pro-grams for iguanas have successfully raised publicawareness regarding iguana conservation through anannual Iguana Day Celebration (Werner 1991). In bothcountries, the event is widely attended and has had asignificant positive impact on the attitude of local peo-ple toward iguanas and their tropical forest habitat.

Wildlife management trainingIn addition to educating the general public, programsalso need to be developed for training local wildlifemanagers. At the minimum, these programs should

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incorporate information about the basic biology ofiguanas. If managers could also be trained in standardmethods of marking (e.g., implanted transponder tags,crest scale and toe-clipping) and censusing iguanapopulations, then regular patrols through iguana habi-tat could yield valuable survey information.Additional training in the area of plant species identi-fication and vegetation transect methods would allowregular assessments of iguana habitats to be made. Inareas where mongooses and feral pigs occur, it mayalso be important to instruct wildlife managers inoptions for nest protection and artificial incubation ofeggs collected from disturbed nest sites. Where para-sitism or disease is a conservation concern, it wouldbe useful for wildlife managers to have experience inroutine blood collection and sample preparation forhealth screening purposes. Finally, because theresponsibility for any ongoing predator control pro-grams will probably fall on local wildlife managers,they should be instructed in use of humane but effec-tive methods that minimize the risk to iguanas andother non-target species.

EcotourismEcotourism has been defined as "low impact naturetourism which contributes to the maintenance ofspecies and habitats either directly through a contri-bution to conservation and/or indirectly by providingrevenue to the local community sufficient for localpeople to value, and therefore protect, their wildlifeheritage area as a source of income" (Goodwin 1996).In order to be successful, it must be ecologicallysound, economically viable, and socially equitable forlocal communities, particularly on small islands andother fragile environments (World TourismOrganisation 1995). Ecotourism not only potentiallyprovides a means for conservation education at thenational and international levels, but also can be avaluable source of funding for habitat management.Conversely, if not conducted in a sensitive manner,ecotourism can have devastating negative effects,including pollution, overconsumption of resources,disturbance of wildlife, destruction of vegetation, anderosion (Goodwin 1996). To ensure that ecotourismresults in more good than harm to the environment, itis imperative that it be carefully controlled and regu-lated at both the local and national levels.

The Ecotourism Society (1993) has published anexcellent guidebook for conducting ecologically andculturally sensitive ecotourism programs. Amongother recommendations, they emphasize that eco-tourism should 1) minimize the negative effects of vis-itors on local habitats and cultures through provisionof educational materials prior to visitors entering nat-ural areas, 2) provide tours consisting only of small,

manageable groups with adequate leadership to mini-mize disturbance, 3) make a significant financial con-tribution to conservation of the region or species im-pacted, 4) employ local community members when-ever possible, and 5) alert all visitors to the fragility ofthe habitat and needs of sensitive species, includingany local legislation or regulations devoted to theirprotection. Local people need to be encouraged to par-ticipate in decision-making regarding the quantity,location, and timing of visits by tourists (King andStewart, 1996). If community members do not re-ceive direct benefits from ecotourism, there will be noincentive for them to abandon other, more destructiveuses of the habitat. Before ecotourism can begin togenerate significant conservation benefits, it is alsoimportant that a basic infrastructure be in place, in-cluding trained guides, interpretive materials, and vis-itor information centers (Jacobson and Lopez 1994).

In addition to these general considerations, specialconcerns for West Indian iguanas include discouragingtourists from feeding iguanas, which may not onlydisrupt their water balance but may also cause them tolose their fear of people and other potential predators.When photographing iguanas, tourists need to bemade aware of the dangers of approaching animals tooclosely and trampling sensitive vegetation. Visits bytour groups during the nesting season may disruptgravid females from digging nest holes and inhibithatching young from dispersing away from the nestclearing. For these reasons, ecotourism at these times ofyear will need to be curtailed. Finally, long-term mon-itoring will be critical to determining whether eco-tourism is having detrimental effects on reproductivesuccess of iguanas or other native wildlife.

Iguana watching is a popular pastime at the U.S.Naval Base at Guantánamo Bay, Cuba.

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Appendix 1. List of Conservation Agencies and Organizations

Bahamas

Bahamas National Trust, PO Box N4105,Nassau, Bahamas

Conservation Office, Department of Agriculture,Ministry of Agriculture and Fisheries,PO Box N3028, Nassau, Bahamas

Bermuda

Bermuda Aquarium, Natural History Museum,and Zoo, PO Box FL 145, Flatts Fl Bx, Bermuda

Conservation and Research for Island Speciesand Insular Systems (C.R.I.S.I.S.),PO Box HM 690, Hamilton HMCX, Bermuda

British Virgin Islands

National Parks Trust, Ministry of Natural Resources,Box 860, Road Town, Tortola, British Virgin Islands

Guana Island Wildlife Sanctuary,administered by The Conservation Agency,6 Swinburne Street, Jamestown, RI 02835 USA

Cayman Islands

National Trust for the Cayman Islands,PO Box 31116 SMB, Grand Cayman,Cayman Islands

Protection and Conservation Unit,Department of the Environment,Cayman Islands Government, PO Box 486 GT,Grand Cayman, Cayman Islands

Chief Agricultural and Veterinary Officer,Department of Agriculture,Cayman Islands Government, PO Box 459 GT,Grand Cayman, Cayman Islands

Cuba

Centro Nacional de Areas Protegidas, Calle 18ANo. 4114, Miramar Playa, Ciudad Habana, Cuba

Empresa Nacional para la Protecciónde la Flora y Fauna,Carretera de Batabano km. 23 1/2, San José, Cuba

Museo Nacional de Historia Natural,Capitolio Nacional, La Habana, Cuba

Instituto de Ecologia y Sistemática,Academia de Ciencias de Cuba,Carretera de Varone km 3 1/2, Ciudad Habana, Cuba

Dominican Republic

Proyecto Biodiversidad, Programa de las NacionesUnidas para el Desarollo, PO Box 1424,Mirador Sur, Santo Domingo, Dominican Republic

Departamento Zoología, Parque Zoologico Nacional,ZOODOM, Santo Domingo, Dominican Republic

Departamento de Vida Silvestre,SURENA, Secretaria de Estado de Agricultora,Santo Domingo, Dominican Republic

Grupo Jaragua, El Vergel,Santo Domingo, Dominican Republic

Jamaica

Hope Zoo, Hope Gardens,Ministry of Agriculture,Kingston 6, Jamaica

Jamaica Conservation and Development Trust,46 Duke Street, Box 1225,Kingston 8, Jamaica

Jamaica Environment Trust,58 Half Way Tree Road,Kingston 10, Jamaica

Jamaican Iguana Research and Conservation Group,c/o Peter Vogel, Department of Life Sciences,University of the West Indies,Kingston 7, Jamaica

National Environmental Societies Trust,46 Duke Street,Kingston 8, Jamaica

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Natural Resources Conservation Authority,53 1/2 Molynes Road,Kingston 10, Jamaica

South Coast Conservation Foundation,91A Old Hope Road,Kingston 6, Jamaica

Lesser Antilles

Forestry and Wildlife Division, Ministry ofAgriculture, Botanic Gardens, Roseau, Dominica

Association pour l'Etude et la protection des Vertébrésdes petites Antilles (AEVA), c/o Barré,Belair Desrozieres, 97170 Petit Bourg, Guadeloupe,French West Indies

Puerto Rico

Department of Natural and Environmental Resources,PO Box 9066600, San Juan, Puerto Rico 00906

Centro de Informacion Ambiental del Caribe (CIAC),Universidad Metropolitana,Apartado 21150,Río Piedras, Puerto Rico 00928

Chelonia, Sociedad Herpetologica de Puerto Rico,Universidad Metropolitana,Apartado 21150 (#22),Río Piedras, Puerto Rico 00928

International Institute of Tropical Forestry,USDA Forest Service, P.O. Box 25000,Rio Piedras, Puerto Rico 00928

Turks and Caicos Islands

Turks and Caicos National Trust, Butterfield Square,Providenciales, Turks and Caicos Islands

Department of Environment and Coastal Resources,Ministry of Natural Resources, South Base,Grand Turk, Turks and Caicos Islands

108

Appendix 2. Criteria for IUCN Red List Threat Categories (1994)

B. Extent of occurrence estimated to be lessthan 100km2 or area of occupancy estimated to beless than 10km2, and estimates indicating any twoof the following:

C. Population estimated to number less than 250mature individuals and either:

ENDANGERED (EN)A taxon is Endangered when it is not CriticallyEndangered, but is facing a very high risk of extinc-tion in the wild in the near future, as defined by anyof the following criteria:A. Population reduction in the form of either ofthe following:

1. An observed, estimated, inferred, or suspectedreduction of at least 50% over the last 10 yearsor three generations, whichever is longer, basedon any of the following:

(a) direct observation(b) an index of abundance appropriate for thetaxon(c) a decline in area of occupancy, extent ofoccurrence, and/or quality of habitat(d) actual or potential levels of exploitation(e) the effects of introduced taxa, hybridiza-tion, pathogens, pollutants, competitors, orparasites.

2. A reduction of at least 50%, projected or sus-pected to be met within the next 10 years or threegenerations, whichever is longer, based on anyof (b), (c), (d), or (e) above.

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1. An estimated continuing decline of at least25% within three years or one generation,whichever is longer, or

2. A continuing decline, observed, inferred, orprojected, in numbers of mature individuals andpopulation structure in the forms of either:

(a) severely fragmented (i.e., no subpopulationestimated to contain more than 50 mature indi-viduals)(b) all individuals are in a single subpopulation.

D. Population estimated to number less than 50mature individuals.

E. Quantitative analysis showing the probabilityof extinction in the wild is at least 50% within 10years or three generations, whichever is longer.

1. Severely fragmented or known to exist at nomore than one location.

2. Continuing decline, observed, inferred, orprojected, in any of the following:

(a) extent of occurrence(b) area of occupancy(c) area, extent, and/or quality of habitat(d) number of locations or subpopulations(e) number of mature individuals.

3. Extreme fluctuations in any of the following:

(a) extent of occurrence(b) area of occupancy(c) number of locations or subpopulations(d) number of mature individuals.

2. A reduction of at least 80%, projected or sus-pected to be met within the next 10 years orthree generations, whichever is longer, based onany of (b), (c), (d), or (e) above.


1. An observed, estimated, inferred, or suspect-ed reduction of at least 80% over the last 10years or three generations, whichever is longer,based on any of the following:

CRITICALLY ENDANGERED (CR)A taxon is Critically Endangered when it is facing anextremely high risk of extinction in the wild in theimmediate future, as defined by any of the followingcriteria:A. Population reduction in the form of either ofthe following:

B. Extent of occurrence estimated to be lessthan 5,000km2 or area of occupancy estimated tobe less than 500 km2, and estimates indicating anytwo of the following:

VULNERABLE(VU)A taxon is Vulnerable when it is not CriticallyEndangered or Endangered but is facing a high risk ofextinction in the wild in the medium-term future, asdefined by any of the following criteria:

A. Population reduction in the form of either ofthe following:

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1. Severely fragmented or known to exist at nomore than five locations.

2. Continuing decline, observed, inferred, orprojected, in any of the following:




C. Population estimated to number less than2,500 mature individuals and either:

1. An estimated continuing decline of at least20% within five years or two generations,whichever is longer, or

2. A continuing decline, observed, inferred, orprojected, in numbers of mature individuals andpopulation structure in the forms of either:

(a) severely fragmented (i.e., no subpopulationestimated to contain more than 250 matureindividuals)(b) all individuals are in a single subpopula-tion.

D. Population estimated to number less than250 mature individuals.

E. Quantitative analysis showing the probabilityof extinction in the wild is at least 20% within 20years or five generations, whichever is longer.

1. An observed, estimated, inferred, or suspectedreduction of at least 20% over the last 10 years orthree generations, whichever is longer, based onany of the following:


2. A reduction of at least 20%, projected or sus-pected to be met within the next ten years orthree generations, whichever is longer, based onany of (b), (c), (d), or (e) above.

B. Extent of occurrence estimated to be less than20,000km2 or area of occupancy estimated to beless than 2,000km2, and estimates indicating anytwo of the following:

1. Severely fragmented or known to exist at nomore than ten locations.

2. Continuing decline, observed, inferred, or pro-jected, in any of the following:




C. Population estimated to number less than10,000 mature individuals and either:

1. An estimated continuing decline of at least 10%within 10 years or three generations, whichever islonger,

D. Population very small or restricted in theform of either of the following:

E. Quantitative analysis showing the probabili-ty of extinction in the wild is at least 10% within100 years or five generations, whichever is longer.

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1. Population estimated to number less than1,000 mature individuals.

or2. A continuing decline, observed, inferred, orprojected, in numbers of mature individuals andpopulation structure in the forms of either:

(a) severely fragmented (i.e., no subpopulationestimated to contain more than 1,000 matureindividuals)(b) all individuals are in a single subpopula-tion.

2. Population is characterized by an acuterestriction in its area of occupancy (typicallyless than 100 km2) or in the number of locations(typically less than five). Such a taxon wouldthus be prone to the effects of human activities(or stochastic events whose impact is increasedby human activities) within a very short periodof time in an unforeseeable future, and is thuscapable of becoming Critically Endangered oreven extinct in a very short period.

IUCN/SSC Action Plans for the Conservation of Biological Diversity

Action Plan for African Primate Conservation: 1986-1990. Compiled by J.F.Oates and the IUCN/SSC Primate Specialist Group, 1986, 41 pp. (Out of print.)

Action Plan for Asian Primate Conservation: 1987-1991. Compiled by A.A.Eudey and the IUCN/SSC Primate Specialist Group, 1987, 65 pp. (Out of print.)

Antelopes. Global Survey and Regional Action Plans. Part 1. East andNortheast Africa. Compiled by R. East and the IUCN/SSC Antelope SpecialistGroup, 1988, 96 pp. (Out of print.)

Dolphins, Porpoises and Whales. An Action Plan for the Conservation ofBiological Diversity: 1988-1992. Second Edition. Compiled by W.F. Perrin andthe IUCN/SSC Cetacean Specialist Group, 1989, 27 pp. (Out of print).

The Kouprey. An Action Plan for its Conservation. Compiled by J.R. MacKinnon,S.N. Stuart and the IUCN/SSC Asian Wild Cattle Specialist Group, 1988,19 pp.(Out of print.)

Weasels, Civets, Mongooses and their Relatives. An Action Plan for theConservation of Mustelids and Viverrids. Compiled by A. Schreiber, R. Wirth, M.Riffel, H. van Rompaey and the IUCN/SSC Mustelid and Viverrid SpecialistGroup, 1989, 99 pp. (Out of Print.)

Antelopes. Global Survey and Regional Action Plans. Part 2. Southern andSouth-central Africa. Compiled by R. East and the IUCN/SSC AntelopeSpecialist Group, 1989, 96 pp. (Out of print.)

Asian Rhinos. An Action Plan for their Conservation. Compiled by Mohd Khanbin Momin Khan and the IUCN/SSC Asian Rhino Specialist Group, 1989, 23 pp.(Out of print.)

Tortoises and Freshwater Turtles. An Action Plan for their Conservation.Compiled by the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group,1989,47 pp.

African Elephants and Rhinos. Status Survey and Conservation Action Plan.Compiled by D.H.M. Cumming, R.F. du Toit, S.N. Stuart and the IUCN/SSCAfrican Elepnant and Rhino Specialist Group, 1990, 73 pp. (Out of print.)

Foxes, Wolves, Jackals, and Dogs. An Action Plan for the Conservation ofCanids. Compiled by J.R. Ginsberg, D.W. Macdonald, and the IUCN/SSC Canidand Wolf Specialist Groups, 1990, 116 pp.

The Asian Elephant. An Action Plan for its Conservation. Compiled by C.Santiapillai, P. Jackson, and the IUCN/SSC Asian Elephant Specialist Group,1990, 79 pp.

Antelopes. Global Survev and Regional Action Plans. Part 3. West and CentralAfrica. Compiled by R. East and the IUCN/SSC Antelope Specialist Group,1990, 171 pp.

Offers. An Action Plan for their Conservation. Compiled by P.Foster-Turley, S.Macdonald, C. Mason and the IUCN/SSC Otter SpecialistGroup, 1990, 126 pp.

Rabbits, Hares and Pikas. Status Survey and Conservation Action Plan.Compiled by J.A. Chapman, J.E.C. Flux, and the IUCN/SSC LagomorphSpecialist Group, 1990, 168 pp.

Insectivora and Elephant-Shrews. An Action Plan for their Conservation.Compiled by M.E. Nicoll, G.B. Rathbun and the IUCN/SSC Insectivore, Tree-Shrew and Elephant-Shrew Specialist Group, 1990, 53 pp.

Swallowtail Butterflies. An Action Plan for their Conservation. Compiled by T.R.New, N.M. Collins and the IUCN/SSC Lepidoptera Specialist Group, 1991, 36 pp.

Crocodiles. An Action Plan for their Conservation. Compiled by J.Thorbjarnarson, H. Messel, F.W. King, J.P. Ross and the IUCN/SSC CrocodileSpecialist Group, 1992, 136 pp.

South American Camelids. An Action Plan for their Conservation. Compiled by H.Torres and the IUCN/SSC South American Camelid Specialist Group, 1992, 58 pp.

Australasian Marsupials and Monotremes. An Action Plan for theirConservation. Compiled by M. Kennedy and the IUCN/SSC AustralasianMarsupial and Monotreme Specialist Group, 1992, 103 pp.

Lemurs of Madagascar. An Action Plan for their Conservation: 1993-1999.Compiled by R.A. Mittermeier, W.R. Konstant, M.E. Nicoll, O. Langrand and theIUCN/SSC Primate Specialist Group, 1992, 58 pp. (Out of print.)

Zebras, Asses and Horses. An Action Plan for the Conservation of Wild Equids.Compiled by P. Duncan and the IUCN/SSC Equid Specialist Group, 1992, 36 pp.

Old World Fruit Bats. An Action Plan for their Conservation. Compiled by S.Mickleburgh, A.M. Hutson, P.A. Racey and the IUCN/SSC Chiroptera SpecialistGroup, 1992, 252 pp. (Out of print.)

Seals, Fur Seals, Sea Lions, and Walrus. Status Survey and ConservationAction Plan. Peter Reijnders, Sophie Brasseur, Jaap van der Toorn, Peter vander Wolf Ian Boyd, John Harwood, David Lavigne, Lloyd Lowry, andthe lUCN/SSC Seal Specialist Group, 1993, 88 pp.

Pigs, Peccaries, and Hippos. Status Survey and Conservation Action Plan.Edited by William L.R. Oliver and the IUCN/SSC Pigs and Peccaries SpecialistGroup and the IUCN/SSC Hippo Specialist Group, 1993, 202 pp.

The Red Panda, Olingos, Coatis, Raccoons, and their Relatives. Status Surveyand Conservation Action Plan for Procyonids and Ailurids. (In English andSpanish) Compiled by Angela R. Glatston and the IUCN/SSC Mustelid,Viverrid, and Procyonid Specialist Group, 1994, 103 pp.

Dolphins, Porpoises, and Whales. 1994-1998 Action Plan for the Conservationof Cetaceans. Compiled by Randall R. Reeves and Stephen Leatherwoodtogether with the IUCN/SSC Cetacean Specialist Group, 1994, 91 pp.

Megapodes. An Action Plan for their Conservation 1995-1999. Compiled byReni W.R.J.Dekker, Philip J.K.McGowan and the WPA/Birdlife/SSC MegapodeSpecialist Group, 1995, 41 pp.

Partridges, Quails, Francolins, Snowcocks and Guineafowl. Status survey andConservation Action Plan 1995-1999. Compiled by Philip J.K. McGowan, SimonD. Dowell, John P. Carroll and Nicholas J.A.Aebischer and theWPA/BirdLife/SSC Partridge, Quail and Francoliln Specialist Group. 1995, 102 pp.

Pheasants: Status Survey and Conservation Action Plan 1995-1999. Compiledby Philip J.K. McGowan and Peter J. Garson on behalf of the WPA/BirdLife/SSCPheasant Specialist Group, 1995, 116 pp.

Wild Cats: Status Survey and Conservation Action Plan. Compiled and editedby Kristin Nowell and Peter Jackson and the IUCN/SSC Cat Specialist Group,1996, 406 pp.

Eurasian Insectivores and Tree Shrews: Status Survey and ConservationAction Plan. Compiled by David Stone and the IUCN/SSC Insectivore, TreeShrew and Elephant Shrew Specialist Group. 1996, 108 pp.

African Primates: Status Survey and Conservation Action Plan (Revised edi-tion). Compiled by John F. Oates and the IUCN/SSC Primate Specialist Group.1996,80 pp.

The Cranes: Status Survey and Conservation Action Plan. Compiled by Curt D.Meine and George W. Archibald and the IUCN/SSC Crane Specialist Group,1996,401 pp.

Orchids: Status Survey and Conservation Action Plan. Edited by Eric Hagsaterand Vinciane Dumont, compiled by Alec Pridgeon and the IUCN/SSC OrchidSpecialist Group, 1996, 153 pp.

Palms: Their Conservation and Sustained Utilization. Status Survey andConservation Action Plan. Edited by Dennis Johnson and the IUCN/SSC PalmSpecialist Group, 1996, 116 pp.

Conservation of Mediterranean Island Plants. 1. Strategy for Action. Compiledby O. Delanok, B. de Montmollin, L. Olivier and the IUCN/SSC MediterraneanIslands Plant Specialist Group, 1996, 106 pp.

Asian Rhinos: Status Survey and Conservation Action Plan (Second edition).Edited by Thomas J. Foose and Nico van Strien and the IUCN/SSC Asian RhinoSpecialist Group, 1997, 112 pp.

Wild Sheep and Goats and their relatives: Status Survey and ConservationAction Plan. Edited by David M. Shackleton and the IUCN/SSC CaprinaeSpecialist Group, 1997, 390 pp.

The Ethiopian Wolf: Status Survey and Conservation Action Plan. Compiledand edited by Claudio Sillero-Zubiri and David Macdonald and the IUCN/SSCCanid Specialist Group, 1997, 123pp.

Cactus and Succulent Plants. Status Survey and Conservation Action Plan.Compiled by Sara Oldfield and the IUCN/SSC Cactus and Succulent SpecialistGroup, 1997, 212 + x pp.

Dragonflies. Status Survey and Conservation Action Plan. Compiled by NormanW. Moore and the IUCN/SSC Odonata Specialist Group, 1997, 28 + v pp.

The African Wild Dog. Status Survey and Conservation Action Plan. Compiledand edited by Rosie Woodroffe, Joshua Ginsberg and David Macdonald and theIUCN/SSC Canid Specialist Group, 1997, 166pp.

Tapirs: Status Survey and Conservation Action Plan. Compiled and edited byDaniel M. Brooks, Richard E. Bodmer and Sharon Matola and the IUCN/SSCTapir Specialist Group, 1997,viii + 164pp.

Grebes: Status Survey and Conservation Action Plan. Compiled by ColinO'Donnel and Jon Fjeldse and the IUCN/SSC Grebe Specialist Group, 1997, vii+ 59pp.

Crocodiles: Status Survey and Conservation Action Plan, 2nd Edition. Edited byJ. Perran Ross and the IUCN/SSC Crocodile Specialist Group, 1998, viii + 96pp.

Hyaenas: Status Survey and Conservation Action Plan. Compiled by Gus Millsand Herbert Hofer and the IUCN/SSC Hyaena Specialist Group, 1998, vi + 154 pp.

North American Rodents: Status Survey and Conservation Action Plan.Compiled and edited by David J. Hafner, Eric Yensen, Gordon L. Kirkland Jr.,and the IUCN/SSC Rodent Specialist Group, 1998, x + 171pp.

Deer: Status Survey and Conservation Action Plan. Compiled by C. Wemmerand the IUCN/SSC Deer Specialist Group, 1998, vi + 106pp.

Bears: Status Survey and Conservation Action Plan. Compiled by C. Servheen,H. Herrera and B. Peyton and the IUCN/SSC Bear and Polar Bear Specialistgroups, 1998, x + 306pp.

Other IUCN/SSC Publications

IUCN Red Lists of Threatened Animals and PlantsRed Lists are lists of all animal or plant species and subspecies that have beenassessed according to the IUCN Red List Categories and Criteria. For eachspecies, the category of threat and relevant criteria are shown, together with therange of states in which the species occurs.

IUCN Policies and GuidelinesPolicies and Guidelines are short, A5 size booklets offering scientifically-basedconservation principles and guidelines to aid decision-making at both the glob-al and national level.

Monographs (arranged by topic)CITES; Crocodiles; Educational Booklets on Mammals; Marine Turtles; Plants;Trade; Others

Occasional Papers SeriesOccasional Papers include overviews on the conservation status of species andproceedings of meetings.

A more detailed list of IUCN/SSC publications is available from the SSC office,Rue Mauverney 28, CH 1196 Gland, Switzerland.Tel: +41 22 999 0150, Fax: +41 22 999 0015, E-mail: [email protected]

IUCN/Species Survival Commission

The Species Survival Commission (SSC) is one of six volunteer commissions of IUCN - TheWorld Conservation Union, a union of sovereign states, government agencies and non-governmental organizations. IUCN has three basic conservation objectives: to secure theconservation of nature, and especially of biological diversity, as an essential foundation for thefuture; to ensure that where the earth's natural resources are used this is done in a wise,equitable and sustainable way; and to guide the development of human communities towardsways of life that are both of good quality and in enduring harmony with other components ofthe biosphere.

The SSC's mission is to conserve biological diversity by developing and executing programsto save, restore and wisely manage species and their habitats. A volunteer network comprisedof nearly 7,000 scientists, field researchers, government officials and conservation leaders fromnearly every country of the world, the SSC membership is an unmatched source of informationabout biological diversity and its conservation. As such, SSC members provide technical andscientific counsel for conservation projects throughout the world and serve as resources togovernments, international conventions and conservation organizations.

The IUCN/SSC Action Plan series assesses the conservation status of species and theirhabitats, and specifies conservation priorities. The series is one of the world's most authoritativesources of species conservation information available to nature resource managers,conservationists and government officials around the world.

IUCN Species Survival CommissionRue Mauverney 28, CH-1196 Gland, Switzerland.Tel: + +41 22 999 01 53, Fax: + +41 22 999 00 15E-mail: [email protected]

IUCN Publications Services Unit,219c Huntingdon Road, Cambridge, CB3 ODL, UK.Tel: + +44 1223 277894, Fax: + +44 1223 277175E-mail: [email protected]

IUCNThe World Conservation Union S P E C I E S S U R V I V A L C O M M I S S I O N

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