ENCUENTRO Sede Pirineos
Restauración de la biodiversidad y los servicios ecosistémicos Titulo de la ponencia: Restauración de fauna insular amenazada Ponente: John E. Fa Fecha: 5/09/2011
Dirigido por: José María Rey Benayas
Restoring threatened island faunas: reptiles in Mauritius
Prof. John E. Fa, Durrell
Mascarenes Islands The Mascarene Islands are a group of islands in the South-West of the Indian Ocean, consisting of: Reuni贸n, 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 Reuni贸n).
Mauritius
Reuni贸n
The importance of islands • 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 17th Century, 72% of all vertebrate extinctions have occurred on islands
The importance of islands
• Mascarenes: Réunion, Mauritius, Rodrigues • In the last 400 years, 89% of reptile extinctions have A bias for island extinctions, the Mascarenes AFRICA occurred higher than other vertebrates accounts on for islands almost – half of the 38 known extinctions INDIAN OCEAN
mostly Mascarenes the large reptiles that Caribbean Mediterranean lost from islands MADAGASCARhave been Seychelles Cape Verde Galapogos The current loss of reptile New Zealand Tonga is considered as diversity Africa a GLOBAL CRISIS! Australia Mexico Panama
Mauritius still maintains an important reptile community…
400ya Mauritius pristine
• 671 species of plant 46% endemic to Mauritius
• The forests supported 22 types of land bird, 12 endemic to Mauritius, such as the dodo
The forests also unique reptiles22 endemic • Mauritius had 23 supported different types of reptile,
• Except for bats, Mauritius never used to have mammals
• With no terrestrial mammals, Mauritius had a reptile and bird dominated ecosystem • REPTILIAN SEED PREY HERBIVORES for DISPERSERS other of larger reptiles & POLLINATORS and PREDATORS birds, reptiles andbirds invertebrates maintaining the natural habitat through browsing & grazing allowing habitat regeneration
• Whilst the forests supported the reptiles and birds 1638 people settled in Mauritius • Reptiles helped to support the forests and the forests were rapidly destroyed
Many animals from other countries 1773 1835 1872 1935 <2% Today Reptiles
Birds
Mammals
â&#x20AC;˘ Some managed tospecies survive on 7 ofMauritius the 49 surrounding were completely lostinvasion from - the EXTINCT Deforestation and caused loss of islands, the disturbance was not as severe >60% ofwhere reptiles from the mainland â&#x20AC;˘ Created many gaps in the ecosystem > vulnerability to disturbance and further species loss
Round Island â&#x20AC;˘ One of the few places not invaded by rats
Round Island • The Became thealso lastsupports location on Earthpopulations to find: island healthy of other endemic and native reptile species
Keeled scaled boa,Phelsuma Casarea dussumieri Gunthers gecko, guentheri
Ornate day gecko, Phelsuma ornata
Bojer’s skink, Gongylomorphus bojerii
HOME TO A REMNANT REPTILE COMMUNITY THAT USED TO OCCUR THROUGHOUT MAURITIUS Telfairs night skink, Leiolopisma telfairii Durrell’s gecko, Bouton’s skink, Nactus durrelli Cryptoblepharus boutonii
Other Islands of importance
Ilot Vacoas Bojerâ&#x20AC;&#x2122;s skink Lesser night gecko
Other Islands of importance
Orange-tail skink
The need for conservation
The future survival of unique reptile species and communities was at great risk, particularly those restricted to single islands Action had to be taken
The need for conservation Island restoration and reptile research been strong support for re-establishing These actions have been the backbone to species Over the past three decades the Forestry Service, Workresearch was started to restore Round Island and • There has been extensive research intohas reptile This has led to new discoveries of ecology, conservation, captive husbandry, genetics, the foundation for: island reptile communities elsewhere conservation on the surrounding islands Durrell, MWF and NPCS the driving force:taxonomy, other islands around Mauritius species and populations on other islands health and disease, and past and present distributions – Restore missing ecological processes and island biodiversity Habitat restoration TRANSLOCATION – the of long-term survival of endangered reptiles – Enhance Eradication mammalian predators and herbivores
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 â&#x20AC;˘ What are the risks at the release site: â&#x20AC;&#x201C; Nature reserves or sites for proposed development â&#x20AC;&#x201C; Are they frequently visited, what are the risks of species invasion
Deciding what goes where and when â&#x20AC;˘ These are important issues for translocation â&#x20AC;˘ Sometimes it is necessary to act without having all the information
Re-building Mauritian reptile communities â&#x20AC;˘ In 2006, we initiated the first lizard translocations â&#x20AC;˘ To date we have translocated five species to four islands
Re-building Mauritian reptile communities • 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
Re-building Mauritian reptile communities • With skinks most recently found on Ile aux Fouquets – we started restoring a population there – Jan 07 – 20 skinks to Ile aux Fouquets
– A year later - no decline on Ilot Vacoas moved a further 20 skinks
Re-building Mauritian reptile communities â&#x20AC;˘ In just over two years we have doubled the global population of this subspecies
Re-building Mauritian reptile communities â&#x20AC;˘ With the skinks doing so well we want to move onto the next phase: Restoring the population back to Ile de la Passe â&#x20AC;˘ 2010 release individuals onto Ile de la Passe
Re-building Mauritian reptile communities • Fossil evidence that the of Bojer’s were on Ile aux However, the presence theseskinks invasive predators has Aigrettes andusSoutheast coastlarger of Mauritius not stopped reintroducing skinks: • 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
Re-building Mauritian reptile communities • Telfair’s skink Leiolopisma telfairii – – – –
Restricted toofRound oncepopulation widespread Dec 06 to Feb 07 Island, Restoration Round Islandbut = skink from below Populations destroyed byQuoin rats 5,000 to more than 30,000 260 to Ile aux Aigrettes 250 skinks Gunners – Sufficiently high population to remove some for translocation
Re-building Mauritian reptile communities • 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
Re-building Mauritian reptile communities • Telfair’s skink Leiolopisma telfairii – For Gunners Quoin
• • •
All reptiles endemic/native known to have co-existed Skinks recorded there 150 -years ago Rat great increase in reptile abundance Ratseradication eradicated=(1995) Telfair’s skinks restore natural predator-prey Habitat very degraded, but structurally sufficient • relationships Abundant food sources – fruits, invertebrates, reptiles
Re-building Mauritian reptile communities
â&#x20AC;˘ Re-establishing a natural seed disperser, pollinator, predator, scavenger of carrion and prey item for future translocations
• Native seed dispersal is occurring • No severe –ve impacts upon endemics • Major impact upon introduced species: Wolf snakes Shrews remain a African land snail Agamid lizardhave not been detected problem… population encounter rates for more than declined from two 10% of pre-skink years 40,000 to 6,000 rates
Initially the shrew from 600 to to be Drought thought have skink recruitment Permitted an in prevented shrews - now thought • The impact ofincrease thetopopulation release hasdeclined been very positive st year 70 soeggs, population naturally started to decline in 1the eating skink preventing recruitment… for restoration of Ile aux Aigrettes
Re-building Mauritian reptile communities
• From studying the population – we realise that had we released twice as many skinks the shrews would have • With shrews gone and no snakes – the island is then been eradicated open for Bojer’s skink re-establishment • Now planning for the release of more skinks
Re-building Mauritian reptile communities • On Gunner’s Quoin
By 2012 we will able to theskinks skinks main However, Gunner’s Quoin is also open to other Recruitment is be occurring: >7,000 by 2012 •• Native seed dispersal is restore also occurring No negative impacts upon resident endemics predator – the Round Island boa reintroductions:
Re-building Mauritian reptile communities • Orange-tail skink, Gongylomorphus fontenayi sp. – Thought to have been No immediate plans to widespread work on thethroughout species 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
Re-building Mauritian reptile communities • Orange-tail skink, Gongylomorphus fontenayi sp. – 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
Re-building Mauritian reptile communities â&#x20AC;˘ Orange-tail skink, Gongylomorphus fontenayi sp. â&#x20AC;˘ In Feb 2008 we translocated 82 skinks to Gunners Quoin
Northern Mauritius
Re-building Mauritian reptile communities • 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
Re-building Mauritian reptile communities â&#x20AC;˘ Translocation successful
â&#x20AC;˘ 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?
â&#x20AC;˘ One of the reptiles lost from Flat Island was the lesser night gecko
• MONITORING Prior to release progress each reptile and impact was given is aits major own component identity to aid of in any post translocation translocation monitoring
– Telfair’s skinks were PIT tagged – Species too small for tagging given photographic IDs – Pattern of scaring, missing toes/claws, tail breaks recorded
• Individual identity Compare health and disease status of the reptiles over time •• Determine and between – Dispersal andislands distribution – Survival, recruitment and population size (recapture rates) ## # # # ### ### # # ### ##### #### ### # ### # #
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Telfair’s skinks on Gunners Quoin
– Habitat utilisation and niche shifts
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• Monitoring populations • Investigate Created lineIMPACT transects onon terrestrial the islands vertebrates to estimate and invertebrates over time populations – populations – vertebrate Monitor invertebrate diversity Measuring the impact of removingand reptiles for using translocation, • Pitfall trappingparticularly for small isolated populations • Litter extraction
Piece by piece we hope to rebuild island communities to save species from extinction and sustain biodiversity