restauracion_huesca_jfa

Sede Pirineos

Restauración de la biodiversidad y los

servicios ecosistémicos

Dirigido por:José María Rey Benayas

Titulo de la ponencia: Restauración de fauna insular amenazadaPonente: John E. FaFecha: 5/09/2011

ENCUENTRO

Restoring threatened island faunas: reptiles in Mauritius

Prof. John E. Fa, Durrell

The Mascarene Islands are a group of islands in the South-West of the Indian Ocean, consisting of: Reunión, Mauritius, Rodrigues, las islas Agalega y and the Cargados Carajos.

Administratively, they belong to Mauritius (islas de Mauritius, Rodrigues, Agalega y Carajos) and to France (Departament of Reunión).

Mascarenes Islands

Mauritius

Reunión

• Islands support high levels of endemicity– Evolution in isolation forms unique ecosystems– Islands are hotspots for biodiversity

• Isolation, co-evolved relationships, naturally restricted ranges > vulnerability to extinction

• Since the 17 th Century, 72% of all vertebrate extinctions have occurred on islands

The importance of islandsThe importance of islandsThe importance of islandsThe importance of islands

• Mascarenes: R éunion, Mauritius, Rodrigues

Mauritius still maintains an important reptile community…

• In the last 400 years, 89% of reptile extinctions h ave occurred on islands – higher than other vertebrates

mostly the large reptiles that have been lost from islands

The current loss of reptile diversity is considered as a GLOBAL CRISIS!

The importance of islandsThe importance of islandsThe importance of islandsThe importance of islands

Mascarenes

Caribbean

Mediterranean

Seychelles

Cape Verde

Galapogos

New Zealand

Tonga

Africa

Australia

Mexico

Panama

• A bias for island extinctions, the Mascarenes accounts for almost half of the 38 known extinction sAFRICA

MADAGASCAR

INDIAN OCEAN

• 671 species of plant 46% endemic to Mauritius

400ya Mauritius pristine

• The forests supported 22 types of land bird, 12 end emic to Mauritius, such as the dodo

• The forests also supported unique reptiles• Mauritius had 23 different types of reptile, 22 end emic

• Except for bats, Mauritius never used to have mamma ls

• REPTILIAN PREDATORS of birds, reptiles and invertebrates• REPTILIAN PREY for other larger reptiles and birds• REPTILIAN HERBIVORESmaintaining the natural habitat through browsing & graz ing

• REPTILIAN SEED DISPERSERS & POLLINATORSallowing habitat regeneration

• With no terrestrial mammals, Mauritius had a reptil e and bird dominated ecosystem

• Whilst the forests supported the reptiles and birds• Reptiles helped to support the forests

1638 people settled in Mauritius and the forests were rapidly destroyed

1773183518721935Today <2%Many animals from other countries

MammalsBirds

Reptiles

• Deforestation and species invasion caused the loss of >60% of reptiles from the mainland

• Created many gaps in the ecosystem > vulnerability to disturbance and further species loss

• Some managed to survive on 7 of the 49 surrounding islands, where the disturbance was not as severe

• Some were completely lost from Mauritius - EXTINCT

Round Island

• One of the few places not invaded by rats

Round Island

• Became the last location on Earth to find:

Gunthers gecko, Phelsuma guentheri

Telfairs skink, Leiolopisma telfairiiDurrell’s night gecko, Nactus durrelli

Keeled scaled boa, Casarea dussumieri

• The island also supports healthy populations of oth er endemic and native reptile species

Ornate day gecko, Phelsuma ornata Bojer’s skink, Gongylomorphus bojerii

Bouton’s skink,Cryptoblepharus boutonii

HOME TO A REMNANT REPTILE COMMUNITY THAT USED TO OCCUR THROUGHOUT MAURITIUS

Other Islands of importance

Ilot Vacoas Bojer’s skinkLesser night gecko

Other Islands of importance

Orange-tail skink

The need for conservation

The future survival of unique reptilespecies and communities was at great risk,

particularly those restricted to single islands

Action had to be taken

The need for conservation• Over the past three decades the Forestry Service,

Durrell, MWF and NPCS the driving force:– Habitat restoration– Eradication of mammalian predators and herbivores

• There has been extensive research into reptile ecology, conservation, captive husbandry, genetics, taxonomy, health and disease, and past and present distributions

• These actions have been the backbone to species conservation on the surrounding islands

• There has been strong support for re-establishing island reptile communities elsewhere– Restore missing ecological processes and island biodiversity– Enhance the long-term survival of endangered reptiles

• Island restoration and reptile research has been the foundation for:

TRANSLOCATION

• This research has led to new discoveries of species and populations on other islands

• Work was started to restore Round Island and other islands around Mauritius

Translocation• The movement of a species from one location with

free release in another – 3 types:– Introduction: species release outside its natural range– Re-introduction: species release within its past former range– Re-stocking: species release within an existing population

Translocation• Re-introduction and re -stocking are

common and powerful conservation tools

• However, where do we start?– How do we decide what goes where and

when?

Deciding what goes where and when• First we need to identify the species we can

translocate based on knowledge of their ecology– Habitat requirements– Food requirements– Position/role in ecosystem

(Cannot establish a predator without its prey!)

Deciding what goes where and when• Need to know:

– Past distribution (history, fossils, associated species)– What caused the loss within the past distribution– Is the cause still present– Are there other predators or competitors that could

prevent re-establishment

Deciding what goes where and when• How vulnerable is:

– the donor population we want to translocate from(removal of individuals does not cause extinction)

– the recipient populations at the release location(adding a predator/competitor does not cause extinction)

Deciding what goes where and when• What are the risks at the release site:

– Nature reserves or sites for proposed development– Are they frequently visited, what are the risks of species

invasion

Deciding what goes where and when• These are important issues for translocation

• Sometimes it is necessary to act without having all the information

Re-building Mauritian reptile communities• In 2006, we initiated the first lizard translocations• To date we have translocated five species to four islands

• Ilot Vacoas Bojer’s Skink, Gongylomorphus bojerii sp.

– Restricted to Ilot Vacoas, only 1ha!– 3-400 skinks inhabit the island once widespread in SE– A sub-species to the populations

restricted to northern islands

Re-building Mauritian reptile communities

• Historical records – Bojer’s skinks found on:• Ile de la Passe 1930s• Ile aux Fouquets 1970s• Losses coincides with shrew invasion

• Losses elsewhere also caused by wolf snakes and mongoose

• By mid 1990s shrews died out on Ile aux Fouquets• In 2000 shrews eradicated on Ile de la Passe


– Jan 07– 20 skinks to Ile aux Fouquets

– A year later - no decline on Ilot Vacoas moved a further 20 skinks

• With skinks most recently found on Ile aux Fouquets – we started restoring a population there


Re-building Mauritian reptile communities• In just over two years we have doubled the global

population of this subspecies

• With the skinks doing so well we want to move onto the next phase:Restoring the population back to Ile de la Passe

• 2010 release individuals onto Ile de la Passe


• Fossil evidence that the Bojer’s skinks were on Ile aux Aigrettes and Southeast coast of Mauritius

• Ile aux Aigrettes ideal site for reintroducing the Bojer’s skink: restored forest, cats and rats removed…

• Efforts to remove the wolf snake and shrew failed


• However, the presence of these invasive predators has not stopped us reintroducing larger skinks:

• Telfair’s skink Leiolopisma telfairii– Restricted to Round Island, but once widespread– Populations destroyed by rats– Dec 06 to Feb 07– 260 skinks to Ile aux Aigrettes– 250 skinks to Gunners Quoin– Restoration of Round Island = skink population from below

5,000 to more than 30,000– Sufficiently high population to remove some for

translocation


• Telfair’s skink Leiolopisma telfairii– For Ile aux Aigrettes

• We knew that skinks were present in the southeast• Much of the natural habitat restored

• Rats and cats removed from the island - 1991• Sufficient food – native/exotic• Predicted the skinks would predate wolf snakes and

compete with shrews and other exotic species still on the island



• Telfair’s skink Leiolopisma telfairii– For Gunners Quoin

• Skinks recorded there 150 years ago• Rats eradicated (1995)• Habitat very degraded, but structurally sufficient• Abundant food sources – fruits, invertebrates, reptiles

• All reptiles endemic/native - known to have co-existed• Rat eradication = great increase in reptile abundance• Telfair’s skinks restore natural predator-prey

relationships

• Re-establishing a natural seed disperser, pollinator, predator, scavenger of carrion and prey item for future translocations


• The impact of the release has been very positive for the restoration of Ile aux Aigrettes

• Native seed dispersal is occurring

• No severe –ve impacts upon endemics

• Major impact upon introduced species:

• Initially the shrew population declined from 600 to 70

African land snail population declined from 40,000 to 6,000

Agamid lizard encounter rates 10% of pre-skink rates

Wolf snakes have not been detected for more than two years

Shrews remain a problem …

• Drought thought to have prevented skink recruitment in 1st year so population naturally started to decline

• Permitted an increase in shrews - now thought to be eating skink eggs, preventing recruitment…


• From studying the population – we realise that had w e released twice as many skinks the shrews would have been eradicated

• Now planning for the release of more skinks

• With shrews gone and no snakes – the island is then open for Bojer’s skink re-establishment

• On Gunner’s Quoin

• Native seed dispersal is also occurring


• No negative impacts upon resident endemics• Recruitment is occurring: >7,000 skinks by 2012• By 2012 we will be able to restore the skinks main predator – the Round Island boa

• However, Gunner’s Quoin is also open to other reintroductions:

– No immediate plans to work on the species

Re-building Mauritian reptile communities• Orange-tail skink, Gongylomorphus fontenayi sp.

– Thought to have been widespread throughout lowlands– Only known from Flat Island (1995), rarely seen

– Rats, cats and mice eradicated in 1998– By 2003 the population estimated at least 800– Current population at least 10,000

– Sept 2007 road opened through the population– Many unconfirmed plans to enhance tourism– Similar island developments = musk shrew and wolf

snake = extinction– We needed to take action, whilst healthy population

• Orange-tail skink, Gongylomorphus fontenayi sp.


Northern Mauritius

Re-building Mauritian reptile communities• Orange-tail skink, Gongylomorphus fontenayi sp.

• In Feb 2008 we translocated 82 skinks to Gunners Quoin

• Gunners Quoin selected: only suitable location

– Was most likely present historically– Similar areas with the same microhabitat– Free of exotic species responsible for extinctions– Known to co-exist with the resident reptiles and Telfair’s skink– Restore remnant Gongylomorphus community


• Translocation successful

• Adults appear healthy and recruitment of young is occurring


• Our fears of development justified…• Shrews detected on Flat Island in May 2010

• Decimate reptile populations

• July 2010, permission to move more skinks

• 300 to enhance establishment on Gunner’s Quoin• 90 to attempt to establish a population on Gabriel Island

• Given uncertainty of translocation success, permission granted to collect skinks for captivity in April 2011

• Impact of shrews had been catastrophic – half a million reptiles eaten, no lesser night geckos, no orange-tailed skinks and a few Bojer’s skinks remained

• The following month - Gunner’s Quoin• 22 orange-tailed skinks collected for Durrell• Maintain a captive population until safe to return to Mauritius

• Development of a shrew proof fence• 1ha enclosure = 1,900 orange-tailed skinks

= 2,800 Bojer’s skinks

• Buy more time for shrew research:What do they prefer to eat, can we bait, trap or poison them?

• One of the reptiles lost from Flat Island was the lesser night gecko

• MONITORING progress and impact is a major component of any translocation

– Telfair’s skinks were PIT tagged– Species too small for tagging given photographic IDs– Pattern of scaring, missing toes/claws, tail breaks recorded

• Prior to release each reptile was given its own identity to aid in post translocation monitoring

• Compare health and disease status of the reptiles over time and between islands

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Telfair’s skinks on Gunners Quoin

• Individual identity

• Determine– Dispersal and distribution – Survival, recruitment and population size (recapture rates)

– Habitat utilisation and niche shifts

• Investigate IMPACT on terrestrial vertebrates and invertebrates over time

• Created line transects on the islands to estimate– vertebrate populations– Monitor invertebrate populations and diversity using

• Pitfall trapping• Litter extraction

– Measuring the impact of removing reptiles for translocation, particularly for small isolated populations

• Monitoring populations

Piece by piece we hope to rebuild island communities to save species from extinction

and sustain biodiversity

restauracion_huesca_jfa

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