conservation of the sunda gharial tomistoma schlegelii in ...ecology and behaviour of the sunda...

Conservation of the Sunda gharial Tomistomaschlegelii in Lake Mesangat, IndonesiaR. STUEBING1, R. SOMMERLAD2 & A. STANIEWICZ3

1Field Museum of Natural History, 1400 Lake Shore Drive, Chicago, Illinois 60605-2496,USA, 2Crocodile Conservation Services Europe, Roedelheimer Landstrasse 42, 60487Frankfurt a.M., Germany, and 3University of Bristol, School of Biological Sciences,Woodland Road, Bristol BS8 1UG, United KingdomE-mail: [email protected]

Although featured in many international zoo collec-tions for decades, little was known about the naturalhistory of Sunda gharial Tomistoma schlegelii untilrecently. Zoos rarely keep large individuals and breed-ing success has been low. As late as 1998, even thoughmost conservationists regarded the conservation statusof the species as Endangered, the reality was that overmost of the range the actual status of the Sunda gharialwas Data Deficient. Beginning with surveys of thespecies by international and local scientists in Indo-nesian Sumatra and, later, in Kalimantan, IndonesianBorneo, supported by the International Union forConservation of Nature/Species Survival CommissionCrocodile Specialist Group, more details on the broaddistribution of this crocodilian came to light. Ironi-cally, rediscovery of a large and healthy population ofT. schlegelii in East Kalimantan arose from an oil-palmcompany accessing the area to develop a site calledDanau Mesangat. Subsequently through a cooperationagreement with the oil-palm company’s conservationdepartment and a local foundation, a group of dedi-cated zoos in Europe and America, and the TomistomaTask Force set up by the Crocodile Specialist Group,provided funding for three consecutive years of fieldstudies by a research group. These studies investigatedthe ecology of T. schlegelii and of a sympatric popula-tion of the Critically Endangered Siamese crocodileCrocodylus siamensis. The role of the zoos, includingtheir role in the development of the research pro-gramme, is described. Accounts are given of the char-acteristics of the Mesangat habitat, some new detailsabout the distribution and abundance of Sunda gharialand Siamese crocodiles in the habitat, and informationabout reproduction in T. schlegelii. In summary, anoverview of threats and suggestions for conservationactions needed at the Mesangat site are provided.

Key-words: endangered species; habitat threats;Indonesia; invasive species; Kalimantan; Siamesecrocodile; Sunda gharial; wetlands.

INTRODUCTION

East Kalimantan, Borneo, remains one of themost forested Provinces in Indonesia, posses-sing not only dryland dipterocarp biomesbut also extensive wetlands under maturekerangas (heath forest) and peat-swamp veg-etation. Most of these disturbed wetlandhabitats occupy a crescent-shaped expanseextending south-westwards from c. 0·5° lati-tude north and south of the equator across themiddle of the Province of East Kalimantan(Kalimantan Timur). The Danau Mesangat–Kenohan Suhuwi sites in the Muara Anca-long District form a major portion of thisconnected basin, within a depression extend-ing from the Kelinjau and Kedang KepalaRivers to as far as the Mahakam River atMuara Kaman (Fig. 1). Plantation agriculturegenerates mixed-use landscapes that con-tain a wide variety of habitats resultingfrom forest regrowth as well as variousanthropogenic regimes, such as subsistencefarms, large plantations, agroforestry proj-ects, subsistence fishermen using small-meshgillnets and electrofishing equipment, com-mercial fish farming, industrial developmentand a plethora of other uses.

Kalimantan Timur has been an importfocus for expansion of oil-palm plantationssince the late 1980s. Despite some obviouslimitations (palms may not grow or producefruit, or may be killed by annual flooding), a

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LAKE MESANGAT, INDONESIA: SUNDA GHARIAL CONSERVATION 137

Int. Zoo Yb. (2015) 49: 137–149

DOI:10.1111/izy.12068

Int. Zoo Yb. (2015) 49: 137–149 © 2014 The Zoological Society of London

mailto:[email protected]

substantial number of the wetland areas arestill earmarked for plantation development.More important for conservation, many ofthese areas contain populations of threa-tened species that appear on the InternationalUnion for Conservation of Nature (IUCN)Red List (IUCN, 2014). However, on landsset aside for plantations or mining (or a com-bination of these), threatened species – manyof them as yet unidentified – face a highprobability of local extinction and possiblyextinctions in the wider landscape. The areascurrently allocated as national parks andnature reserves cannot support adequatelythe range of species diversity that exists. Thisfact has been demonstrated both within andat the periphery of oil-palm estates, wherethreatened and previously unknown species

have been documented by local and interna-tional scientists (Wahyudi & Stuebing,2013).

The Sunda gharial Tomistoma schlegeliiwas an enigma for decades, without any sig-nificant understanding of its ecology, distri-bution and abundance even within theIUCN/Species Survival Commission (SSC)Crocodile Specialist Group. Furthermore,because of the osteoderms in its ventralscales, T. schlegelii was rarely if everexploited commercially as a source of croco-dile leather, so that support of research bythe crocodile-leather industry was limited,or incidental to studies of other species.However, by the mid-1990s more informa-tion had come to light, primarily related tosurveys of other crocodile species, especially

Fig. 1. Map of basic land cover for Mesangat–Kenohan Suhuwi wetland, Indonesia. Study area boundaryindicated in black. SarVision for Yayasan Ulin.

138 REPTILE CONSERVATION


the Salt-water crocodile Crocodylus porosusin Borneo and Sumatra (Cox et al., 1993;Bezuijen et al., 2002, 2003). In 1997, aresearch report from the Indonesian Insti-tute of Sciences (Lembaga Ilmu PengetahuanIndonesia: LIPI), Jakarta, and the Smith-sonian Institution, Washington, DC, USA,on surveys of Siamese crocodile Crocodylussiamensis in Kalimantan, hinted that theSunda gharial was much more widespreadthan had been previously thought (Bezuijenet al., 2013). This was in stark contrast tothe reports from Sumatra, where scientistsinferred that the species was on the vergeof extinction as a result of the impacts oflogging, illegal land clearing and plantationdevelopment (Bezuijen et al., 2002, 2003).The latter findings stimulated the preparationof several papers about the Sunda gharial thatwere presented at the IUCN/SSC CrocodileSpecialist Group Working Meeting in Singa-pore in 1998 (Crocodile Specialist Group,1998). Subsequently, an informal discussiongroup was formed to plan more systematicresearch on the species. The urgency for fieldresearch into the status of the Sunda gharialwas revived at the 2002 Conservation Spe-cialist Group meeting in Gainesville, FL,USA, and the Tomistoma Task Force was setup in 2003, chaired by Grahame Webb. Thegroup was formed from a broad array ofcrocodile field biologists, husbandry special-ists, and several members of governmentwildlife agencies from the main range statesof Indonesia, Malaysia and Thailand.

In 2008, a special Tomistoma Task Forceworkshop in Pattaya, Thailand, targeted thedevelopment of a strategy for expandingfield research on the ecology of the Sundagharial. Later in that same year, a sitecalled Lake Mesangat in the District ofKutai Timur, East Kalimantan, was identi-fied as an important location where studiescould begin. Originally <12 000 ha ofwetland forests, the area is important to thelivelihoods of traditional Kutai fishermen.Because there was easy river access througha tributary of the Mahakam River to thetimber port of Samarinda, in the 1970s theDistrict of Muara Ancalong witnessed a

rapid expansion of intensive forest exploita-tion. At the time of writing all that remainsof the original forest are some smallwooded ‘islands’ or domes lying in deeper,flooded basins. Generally <10 m above sealevel, the Mesangat Lake now forms a land-scape of patchy shrubs and sedges, inter-spersed with irregular groves or lines oftrees (Plate 1). During the El Niño SouthernOscillation events of 1982–1983 and 1997–1998 (Chokkalingam et al., 2005) vast areasexperienced cycles of intensive burning bylocal farmers or immigrants from otherparts of Indonesia. Grasses and shrubspermanently colonized the flat landscape.Habitat disturbance opened the door to awide range of invasive exotic species, suchas Water hyacinth Eichornia crassipes,Floating fern or Giant salvinia Salviniamolesta, apple snails Pomacea spp, Amazonsailfin catfish Liposarcus (Pterygoplichthys)pardalis, Giant snakehead Channa micro-peltes and many others (Plate 2). Despitethe loss of much of the natural vegetationover many decades, visits by local and inter-national scientists have confirmed the pres-ence of T. schlegelii and C. siamensis (Rosset al., 1998; Kurniati et al., 2005) (Plates 3and 4). Mesangat remains home to at leastsix threatened species that have survived oreven thrived in the mosaic of damaged habi-tats, including two species of freshwatercrocodiles, a stork, a river turtle and at leasttwo species of mammals (Table 1).

By 2007, most of the Mesangat wetlandhad been surveyed and sold for the deve-lopment of oil-palm plantations. After twoplanting failures, and discussions with thePT.REA Kaltim Conservation (REA KON)staff, the company decided to restrict itsdevelopment of the site and to investigatepermanent allocation of specific areas forconservation management and sustainableuse.

To date four field reports have been writtenon the Mesangat population of Sunda gharial,and two MSc projects have been completed.In due course the results of these studies,including the bulk of the ecological data, willbe published.



SUPPORT FOR MESANGATCONSERVATION

In 2009, the Danau Mesangat–KenohanSuhuwi area became a logical choice forimplementation of long-term field studies ofboth the Sunda gharial and the Siamesecrocodile (Stuebing & Sommerlad, 2010).The site was the only known location inSouth East Asia where healthy natural popu-

lations of both species occurred in relativeabundance. The early work of the conserva-tion staff of REA KON, and its asso-ciated conservation foundation, the Iron-wood Foundation (Yayasan Ulin), drew theattention of the IUCN Crocodile SpecialistGroup’s Tomistoma Task Force. These some-what disparate bodies began collaborativeecological studies of the crocodiles andtheir habitat. The initial challenge was to find

Plate 1. The landscape around Mesangat Lake, Indonesia, today is made up of patchy shrubs and sedges,interspersed with irregular lines of trees. Rob Stuebing, Yayasan Ulin.

Plate 2. Habitat disturbance in the Mesangat Lake region, Indonesia, made way for a wide range of invasiveexotic species, such as (left) the Water hyacinth Eichornia crassipes in the Abang area and (right) the Water fernSalvinia molesta in the Kenohan Suhuwi wetlands area. Yayasan Ulin.



sources of funding for this relativelyunknown, isolated and degraded habitat.

Support was found from abroad such asthe Mohamed Bin Zayed Species Conserva-tion Fund (Project no. 0925309), Abu Dhabi,United Arab Emirates, and the generosity ofpublic and private zoos and aquariums inEurope and the United States, which pro-vided a well-timed opportunity to initiatein-depth ecological studies of both the threa-tened crocodile species in Mesangat. Anunusual partnership developed between con-servation biologists, the zoological facilitiesand an oil-palm plantation company, and wasunique in providing the means for developinga detailed picture of the autecology of bothT. schlegelii and C. siamensis.

Even though the Sunda gharial has longbeen reared in crocodile ‘tourist’ farms andzoos throughout South East Asia, most hold-ings were of single animals, pairs or smallgroups that were kept in enclosures of limitedsize with the sole purpose of keeping thecrocodiles conspicuously on view for visi-tors. These conditions virtually guaranteedthat little understanding about the naturalecology and behaviour of the Sunda gharialwould ever be achieved. Furthermore, thelack of any commercial value of the skinsor meat of T. schlegelii generated minimalcommercial interest. Nevertheless, the novelappearance of this crocodilian and its secre-tive habits in the wild made the species anexcellent attraction for zoo exhibits and

tourist parks, few of which made any realattempts to breed the species.

Only a few farms made concerted effortsto breed this iconic crocodilian, especiallyUtairatch Crocodile Farm in Samutprakarn,Thailand (owner Uthen Youngpapakorn), andJong’s Crocodile Farm in Kuching, Sarawak,Malaysia (owned by Johnson Jong andfamily), both of which successfully estab-lished sustainable breeding stocks (Plate 5).

The Sunda gharial was a common speciesin European zoological facilities in the 20thcentury. Most specimens were obtained frominternational animal dealers, such as CarlHagenbeck, who founded his company in1848 and became one of the largest wildlifedealers worldwide (Hanson, 2004). Hagen-beck and others kept in close contact withdealers and hunters in Malaysia and Indo-nesia. Singapore developed as the prin-cipal hotspot for the international wildlifetrade, so that most of the T. schlegelii thatcame to Europe in the second half ofthe 20th century originated from dealersbased there. The provenance of thesetraded animals remained essentially un-known (Trutnau & Sommerlad, 2006).

Until the early 1970s, crocodiles weremostly kept in multi-species groups and forthat reason often did not do well, althoughthere were individuals that survived forseveral decades under these suboptimal con-ditions (Sommerlad et al., 2011). Whenmodern zoos sought to transform their imageand practices from that of menageries to‘cageless’ exhibits to promote wildlife con-servation, several crocodilian species gradu-ally disappeared from European collectionsand the number of facilities keeping theSunda gharial also declined.

Because of the scarcity of empiricaldata concerning the conservation status ofT. schlegelii in the wild, and their EndangeredRed List status at that time (IUCN, 2014), theEuropean Association of Zoos and Aquaria(EAZA) was urged by the then Chair of theCrocodile Specialist Group Tomistoma TaskForce, Ralf Sommerlad, at the 2004 EAZAconference in Kolmarden, to establish acaptive-breeding programme for the Sunda

Plate 3. Head of a Sunda gharial Tomistoma schlegeliiat Lake Mesangat, Indonesia. Agata Staniewicz, BristolUniversity.



gharial in European zoological facilities(Shwedick, 2006). The EAZA Reptile TaxonAdvisory Group promptly agreed and setup the European studbook with GonzaloFernandez-Hoyo at Fuengirola Zoo, Spain, asstudbook keeper. In 2006, Fuengirola Zoowas the first zoo in Europe to successfullybreed T. schlegelii, and more were hatched in2010 (Fernandez-Hoyo, 2012). As more zoosbecame interested in exhibiting this large,narrow-snouted crocodilian, several builtnew, spacious and modern exhibits (e.g.Leipzig Zoo, Germany; Dvur Kralove Zoo,Czech Republic). ARTIS Amsterdam, TheNetherlands, recently constructed a newexhibit to house their large old pair ofT. schlegelii, formerly displayed in the reptilehouse (W. Spencer, pers. comm., 2013).

At the time of writing, the Europeanstudbook for T. schlegelii lists 43 individualsat ten European facilities (Fernandez-Hoyo,2012; G. Fernandez-Hoyo, pers. comm.,2013). Protivin Crocodile Zoo in the CzechRepublic now holds the largest group ofSunda gharial in Europe. Outside Europe,the São Paulo Zoo, Brazil, and Taipei Zoo,Taiwan, also joined the European stud-book population and the number of

Plate 4. Female Siamese crocodile Crocodylus siamensis basking on an old nest in the Mesangat wetland,Indonesia. Camera-trap phototograph. Agata Staniewicz, Bristol University/Yayasan Ulin.

Table 1. Threatened vertebrate species in Mesangat,Indonesia: CITES. Convention on InternationalTrade in Endangered Species of Wild Flora andFauna (CITES, 2014); I. CITES Appendix I; II.CITES Appendix II; International Union for Conser-vation of Nature (IUCN): Red List categories: CR,Critically Endangered; EN, Endangered; LC, LeastConcern; VU, Vulnerable (IUCN, 2014).

SPECIESIUCNSTATUS CITES

CURRENTTHREATLEVEL INMESANGAT

Sunda gharialTomistoma schlegelii VU I Moderate

Siamese crocodileCrocodylus siamensis CR I Moderate

Malaysian giant turtleOrlitia borneensis EN II High

Southeast Asiansoftshell turtleAmyda cartilaginea VU II Moderate

Storm’s storkCiconia stormi EN High

Leopard catPrionailurusbengalensis

LC I Moderate

Proboscis monkeyNasalis larvatus EN I Moderate



captive-bred individuals continues to grow.The first T. schlegelii to hatch in the USAoccurred at both the Bronx Zoo, NY, andMiami Zoo, FL, in 1985; since 2008 SanAntonio Zoo, TX, USA, has also beensuccessfully breeding the Sunda gharial(Shwedick et al., 2013).

This growing interest in T. schlegelii andits conservation was well timed to assist theMesangat Conservation Project, set up inearly 2009 by REA-KON.

Confirmation of the presence of theCritically Endangered (CR) Siamese croco-dile C. siamensis at Lake Mesangat led togrowing support for this in situ projectby the Zoologische Gesellschaft für Arten-und Populationsschutz (ZGAP), the Deut-sche Gesellschaft für Herpetologie undTerrarienkunde (DGHT), and several Euro-pean and American zoos. Without the finan-cial, scientific or organizational support ofinstitutions in Germany, including CologneZoo, Dortmund Zoo, Erfurt Zoo, FrankfurtZoo and Neunkirchen Zoo, Protivin Croco-dile Zoo in the Czech Republic and institu-tions in the USA, including the VirginiaAquarium, VA, and the Crocodilian AdvisoryGroup of the Association of Zoos &

Aquariums, field research and conservationactivities at Mesangat would not have beenpossible (Sommerlad, 2012). The MohamedBin Zayed Species Conservation Funddonated significantly to Mesangat conserva-tion, and assistance was also received fromthe IUCN-SSC Crocodile Specialist Groupand its Tomistoma Task Force.

Through the Cologne Zoo and DortmundZoo, the Mesangat Crocodile ConservationProject became a partner project for theWorld Association of Zoos and Aquariums,providing funding and articles for publication(Sommerlad et al., 2010). When the EAZA–IUCN/SSC South East Asia Campaignlaunched in 2011, the Mesangat project wasselected as one of the flagship projects andreceived support from many EAZA (and non-EAZA) institutions (Marseille, 2011).

From 2009 to 2012 European zoos donatedmore than 20 000 Euros to support thefield research of two research students (A.Staniewicz and N. Behler). These fundswere also used to obtain a suitable boat andoutboard motor, and for the renovation ofthe raft-station facilities. Most of the fundsgiven by zoos were collected from visitors,either via a donation funnel for coins beside

Plate 5. Sunda gharial Tomistoma schlegelii on a nest at Jong Crocodile Farm, Kuching, Sarawak, Malaysia. RobStuebing.



posters explaining the conservation project(in the rainforest house at Dortmund Zoo) orby selling information booklets (ProtivinCrocodile Zoo). Cologne Zoo also collectedfunds and provided additional support,including the supervision of the work onSiamese crocodiles by Associate ProfessorDr Thomas Ziegler, who also had some inputinto the Sunda gharial field research.

FIELD RESEARCH 2009–2012

With financial support by European zoos,conservation funds and Yayasan Ulin, from2009 to 2012 Agata Staniewicz of BristolUniversity, UK, conducted extensive fieldstudies into the ecology and populationstructure of T. schlegelii. From 2010 to2012, Natascha Behler of Bonn Univer-sity, Germany, concurrently implemented astudy into the ecology and taxonomy ofthe sympatric and CR Siamese crocodileC. siamensis. Other studies carried out inMesangat included that of aquatic life(Wowor & Hadiaty, 2010), a preliminarycamera-trapping inventory of the mammalfauna and studies of Asiatic softshell turtleAmyda cartilaginea and Malaysian giantturtle Orlitia borneensis (REA Kaltim Con-servation and Yayasan Ulin), and botanicalsurveys of wetland forests (Leong, 2011), allof which were implemented concurrently.

Assisted by local fishermen and YayasanUlin staff, Agata Staniewicz was stationedfor weeks at a time on a simple raft anchoredin the Mesangat wetland. At least 2 monthswere spent mapping and assessing habi-tat characteristics, and conducting spotlightsurveys, mark–recapture studies and investi-gations into the diet of the Sunda gharial. Inorder to account for seasonal differences inwater level and access to the wetlands, obser-vations took place over three separate fieldseasons: during the rainy season of October–December 2010, the dry season of June–September 2011 and a transitional periodfrom May to July 2012. There is a series offield reports on the recent crocodile studies inMesangat (Indraswari & Staniewicz, 2009;Behler, 2011; Staniewicz, 2011b). In addi-

tion, an informational poster on MesangatConservation was prepared for a workingmeeting of the IUCN Crocodile SpecialistGroup in 2010 (Staniewicz, 2011a) (Fig. 2).

Wild juvenile T. schlegelii were found toinhabit predominantly flooded forest areasof Mesangat (A. Staniewcz, unpubl. data)(Plate 6). In total, 30 Sunda gharial were cap-tured over the three field seasons. The appar-ent preference of habitat largely inaccessibleto people, combined with highly secre-tive lifestyle and low capture-and-recapturerates, made it difficult to assess accurately thepopulation size of T. schlegelii in the area.Thestudies thus focused on juveniles, which wereeasier to approach, and habitat partitioningwith the sympatric C. siamensis. The Siamesecrocodile was found predominantly in theopen water areas of Mesangat (A. Staniewicz,unpubl. data; N. Behler, unpubl. data).Juvenile T. schlegelii are apparently general-ist, opportunistic feeders with a diet consist-ing of invertebrates and small vertebrates,similar to that seen in other crocodilians(Taylor, 1979; Platt et al., 2006; A.Staniewicz, unpubl. data). Nesting season wasconfirmed to occur during the dry season(June–September) with mound nests built onland at the base of a tree in close proximity towater, similar to earlier observations, bothpublished (Ross et al., 1998; Bezuijen et al.,2002, 2010) and unpublished (R. Stuebing,unpubl. field data, Sarawak and EastKalimantan) (Plate 7). Preliminary investiga-tions into physiological colour-change abilityin T. schlegelii were also carried out (A.Staniewicz, pers. comm). For additional earlyfield results, see the poster in Fig. 2.

SUSTAINING SUNDA GHARIALWITHIN DEGRADED ECOSYSTEMS

Work in Mesangat was activated in 2008 andincreased in intensity until 2012. Beginningin mid-2013, fieldwork temporarily ceasedand is currently on hold. It is the hope thatthe project will be reactivated in the future,once human and financial resources areavailable, including work on a more effec-tive radio-tracking technique and more



Fig. 2. A poster describing early work carried out in the Mesangat Lake area, Indonesia, on population size anddistribution, seasonal movements, and general biology and feeding ecology for Sunda gharial Tomistomaschlegelii and Siamese crocodile Crocodylus siamensis.



extensive involvement of the village com-munities in Muara Ancalong. A head-starting effort is also planned forT. schlegelii, C. siamensis and at least onespecies of threatened terrapin, althoughall the details are not yet finalized. Astepwise assessment of the commercialvalue of any local or exotic species occur-

ring in Mesangat will be undertaken next toinitiate long-term management for sustain-able consumptive or non-consumptive (e.g.recreation and nature tourism) use of aquaticresources. Active or passive habitat restora-tion will also be implemented at the sametime, with efforts to remove at least someinvasive species.

Plate 6. Wild juvenile Sunda gharial Tomistoma schlegelii inhabit the flooded forest area around Mesangat,Indonesia. Agata Staniewicz, Bristol University/Yayasan Ulin.

Plate 7. Sunda gharial Tomistoma schlegelii build mound nests on land at a base of a tree in close proximity towater around the Mesangat Lake area, Indonesia. Agata Staniewicz, Bristol University/Yayasan Ulin.



Meanwhile the development of oil-palmplantations has continued in the Mesangatarea, and the threats to the wetland and itsthreatened species remain.

THREATS TO T. SCHLEGELII

Habitat destruction by plantationcompanies as well as thelocal government

Efforts continue towards the completionof large-scale conversion of the greaterMesangat–Kenohan Suhuwi wetlands intoplantation agriculture (oil palm or fast-growing timber, such as Acacia spp). Themost serious threat lies with clearing anddraining of extensive wetland sites for plan-tation agriculture. Repeated attempts con-tinue to drain flooded sites of the Mesangat–Kenohan Suhuwi wetland.

Disturbance, harvest and sale ofthreatened species in Lake Mesangat

Crocodile nesting sites continue to beraided by local people who collect and selleggs of both T. schlegelii and C. siamensis,and the occasional crocodile is killed whenit drowns in a fishing net. In addition, theharvest and sale of riverine/wetland turtlesand their eggs, and the hunting of Pro-boscis monkeys Nasalis larvatus as foodcontinues.

Use of toxic, persistent chemicals inagriculture or control of invasivewater weeds

A whole range of invasive exotic aquaticplants continues to spread into the degradedareas of the wetland, dominated by Waterhyacinth E. crassipes and Floating fernS. molesta. These species and others havealready colonized vast areas in thickmasses, forming floating mats that hamperuse of the waterways by local fishermen.The senescent mass then decomposes, cre-ating anoxic conditions in large areas of theLake. Periodically – and only temporarily –

the weeds are attacked by the local fisher-man by spraying non-selective contactherbicides, such as Gramoxone and Paracol,available from oil-palm plantation suppliers.Substantial levels of fertilizer run-off con-tinue to be diverted into the wetland, furtherenhancing the growth of E. crassipes andS. molesta.

PROPOSED FUTURE ACTION

• Extend research to discover the true geo-graphic distribution of T. schlegelii in EastKalimantan (and elsewhere in Borneo)because most current information is stillinadequate or out of date.

• Determine the specific nest requirements,characteristics (temperature, depth, toler-ated level of disturbance) and the real-time distribution of reproductive adultT. schlegelii in the appropriate Mesangathabitat.

• Determine differences in behaviour in dis-turbed versus relatively pristine areas. Forexample, compare the very differentlybehaved T. schlegelii in Tanjung Putting inCentral Kalimantan (where the speciesopenly basks), with the shyness of theanimals observed in Mesangat.

• Initiate a financially robust, long-termradio-tracking study using tower and cell-phone technology. For more extensiveareas satellite-tracking technologies can beused.

• Investigate underwater behaviour ofT. schlegelii, which is a species thatappears to spend extensive periods sub-merged compared with other crocodilespecies in Asia. A permanent network ofhydrophones should be set in place torecord the acoustic behaviour of theT. schlegelii population, as well as thebackground sound characteristics (includ-ing boat traffic) of the surrounding under-water environment.

• Establish the Mesangat–Kenohan Suhuwiwetlands (extending to more than 1000km2) as a formally protected Conser-vation Reserve based on sustainableuse – ensuring the livelihoods of the local



people with traditional means of making aliving.

CONCLUSION

Despite widespread and sometime drasticlevels of disturbance over several decades,Lake Mesangat and the vast surroundingwetland of Kenohan Suhuwi, have quiteremarkably still retained healthy populationsof several threatened species. Because mostfunding for in situ conservation is usuallydirected towards pristine protected areas, thissituation presents conservationists with adilemma: why save a degraded habitat? Thissituation could in fact be a unique opportu-nity to establish a permanent conservationpresence within an area that we know hasthe potential to provide a safe haven forseveral threatened vertebrates (Bezuijenet al., 2010). This is especially true, for thearea around the Mesangat Lake as much ofthe Kenohan Suhuwi wetlands will eventu-ally be abandoned by commercial interests(e.g. plantation agriculture) because of itsinherent unsuitability. The Sunda gharial andSiamese crocodile have already withstoodsome of the worst kinds of disturbance pos-sible: overharvesting of timber, savage fires,introduced invasive species and even poten-tially toxic chemical run-off. Mesangat couldbe one of the most dramatic conservationsuccesses, not only because of the opportu-nity to conserve a large resident populationof T. schlegelii for long-term studies but alsoas a world-class example of ecological resto-ration in the tropics, where such renewal israre. With T. schlegelii and C. siamensis asflagship species, many other threatenedspecies (turtles, wild cats, monkeys, plants)can be restored through sustainable use ofthe living resources of the area, conservingtraditional livelihoods of the fishermen andfarmers of this unique, and despite thedamage wrought by humans, remarkablybeautiful part of Kalimantan.

ACKNOWLEDGEMENTSFor assistance in the field, we are grateful to PT. REAKaltim conservation staff and the staff of the Yayasan

Ulin, especially Soeimah, Kiki, Ingan, Kahang, Daud,Deni, Sunardi and Sebastian. Special thanks also toGareth Jones, Tarto Sugiarto and Hellen Kurniati. Finan-cial support has been generously provided by theMohamed Bin Zayed Species Conservation Fund, AbuDhabi, United Arab Emirates; Dortmund Zoo, Germany(Frank Brandstaetter); Cologne Zoo, Germany (ThomasZiegler); Protivin Crocodile Zoo, Czech Republic(Miroslav Prochazka); Erfurt Zoo, Germany (ThomasKoelpin); Deutsche Gesellschaft für Herpetologie undTerrarienkunde, Mannheim, Germany (Beat Akeret &Peter Buchert); Zoologische Gesellschaft für Arten- undPopulationsschutz, Sachsenhagen, Germany (RolandWirth and Jens-Ove Heckel); Virginia Aquarium, VA,USA (Mark Swingle and Chip Harshaw); and theAssociation of Zoos and Aquariums Crocodilian Advi-sory Group, USA. Our thanks also to the IUCN/SSCCrocodile Specialist Group Tomistoma Task Force(Bruce Shwedick); World Association of Zoos andAquariums (Markus Gusset); IUCN–EAZA SoutheastAsia Campaign; and supporting zoos. Valuable assis-tance from Natascha Behler, Thomas Wilms (FrankfurtZoo, Germany) and Uthen Youngprapakorn, Samut-prakarn, Thailand (Utairatch Crocodile Farm), is alsomuch appreciated.

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CITES (2014): Appendices I, II and III. Châtelaine,Geneva, Switzerland: Convention on International Tradein Endangered Species of Wild Flora and Fauna. Avail-able at http://cites.org/eng/app/appendices.phpCOX, J. H., FRAZIER, R. S. & MATURBONGS, R. A. (1993):Freshwater crocodiles of Kalimantan (IndonesianBorneo). Copeia 1993: 564–566.CROCODILE SPECIALIST GROUP (1998): Crocodiles. Pro-ceedings of 14th working meeting of the Crocodile Spe-cialist Group. Gland, Switzerland, and Cambridge, UK:IUCN/SSC Crocodile Specialist Group.FERNANDEZ-HOYO, G. (2012): EAZA European regionalTomistoma (false gavial) studbook. Fuengirola, Málaga:Bioparc Fuengirola.HANSON, E. (2004): Animal attractions: nature ondisplay in American zoos. Princeton, NJ: Princeton Uni-versity Press.INDRASWARI, K. & STANIEWICZ, A. (2009): Survey ofCrocodylus siamensis and Tomistoma schlegelii inMesangat Lake, Muara Ancalong Village, KutaiKertanegara Regency, East Kalimantan, Indonesia.Samarinda, East Kalimantan: Yayasan Ulin (The Iron-wood Foundation) (unpublished report).IUCN (2014): The Red List of Threatened Species.Gland, Switzerland, and Cambridge, UK: InternationalUnion for Conservation of Nature. Available at http://www.iucnredlist.orgKURNIATI, H., WIDODO, T. & MANOLIS, C. (2005): Surveysof Siamese crocodile (Crocodylus siamensis) habitat inthe Mahakam River, East Kalimantan, Indonesia. Tech-nical report. Bogor: Indonesian Institute of Sciences(LIPI), Research Center for Biology.LEONG, P. K. (2011): Strange encounters of the leafykind: botanising in a peat swamp in East Kalimantan.Gardenwise 37: 16–21.MARSEILLE, M. (2011): Southeast Asia campaign: theMesangat wetland. Zooquaria 76: 8–9.PLATT, S. G., RAINWATER, T. R., FINGER, A. G.,THORBJARNARSON, J. B., ANDERSON, T. A. & MCMURRY, S.T. (2006): Food habits, ontogenic dietary partitioningand observations on foraging behavior of Morelet’scrocodile Crocodylus moreletii in northern Belize. Her-petological Journal 16: 281–290.ROSS, C. A., COX, J. H., KURNIATI, H. & FRAZIER, S.(1998): Preliminary survey of palustrine crocodiles inKalimantan. In Crocodiles. Proceedings of 14th workingmeeting of the Crocodile Specialist Group: 46–79.Gland, Switzerland, and Cambridge, UK: IUCN–TheWorld Conservation Union.SHWEDICK, B. M. (2006): Husbandry and captive repro-duction of the Tomistoma (Tomistoma schlegelii). InProceedings of the 26th, 27th, 28th and 29th interna-tional herpetological symposia on captive propagationand husbandry: 11–21. Gurley, R., Hicks, T. & Hicks, E.(Eds). Lansing, MI: ECO Herpetological Publishing.

SHWEDICK, B. M., SOMMERLAD, R. & WEBB, G. (2013):New hope for the endangered Tomistoma. ReptilesMagazine March: 46–51.SOMMERLAD, R. (2012): Danau Mesangat: WieZoologische Gärten beispielgebend helfen. ZGAPMitteilungen 28(1): 20–22.SOMMERLAD, R., JELDEN, D., NGUYEN, T., STUEBING, R. B.,BOEHME, W. & ZIEGLER, T. (2010): Natural history ofreintroduced and natural Siamese crocodile populations:implications for protection and conservation breeding.WAZA News 3: 28–29.SOMMERLAD, R., SCHMIDT, F. & ZIEGLER, T. (2011):Threatened crocodiles in European Zoos? Reptilia 74:12–17.STANIEWICZ, A. (2011a): Crocodile surveys in MesangatLake, East Kalimantan, Indonesia, October–December2010. In Crocodiles. Proceedings of the 1st regionalspecies meeting: 45–49. Darwin, NT: IUCN/SSCCrocodile Specialist Group. Available at http://www.iucncsg.org/365_docs/attachments/protarea/45-4-766fc157.pdfSTANIEWICZ, A. (2011b): Diet and demography ofTomistoma schlegelii in Mesangat Lake, EastKalimantan, Indonesia: June–September 2011. Bristol:University of Bristol, School of Biological Sciences.Unpublished report for EAZA IUCN/SSC South-east Asia Campaign. Available at http://www.dght-zgap-artenschutz.de/media/projekte/mesangat/2011%20Mesangat%20Tomistoma%20report.pdf (accessed25 September 2012).STUEBING, R. B. & SOMMERLAD, R. (2010): Mesangat –Ein aufregendes Artenschutzprojekt auf Borneo. ZGAPMitteilungen 26(1): 4–7.TAYLOR, J. A. (1979): The foods and feeding habits ofsubadult Crocodylus porosus Schneider in northernAustralia. Australian Wildlife Research 6: 347–359.TRUTNAU, L. & SOMMERLAD, R. (2006): Crocodylians.Their natural history and captive husbandry. Frankfurtam Main: Chimaira.WAHYUDI, D. & STUEBING, R. (2013): Camera trapping asa conservation tool in a mixed-use landscape in EastKalimantan. Journal of Indonesian Natural History 1(2):37–46.WOWOR, D. & HADIATY, R. (2010): Aquatic fauna base-line study at Danau Mesangat, Kutai Timur Regency,East Kalimantan. Technical report. Cibinong: Divisionof Zoology Research Center for Biology (Puslit Biologi)Indonesian Institute of Sciences (LIPI).

Manuscript submitted 7 February 2014;revised 14 August 2014; accepted 21 August2014



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