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The designation of geographical entities in this book, and the presentation of the material, do not imply the expression of any opinion whatsoever on the part of IUCN or any of the funding organizations concerning the legal status of any country, territory, or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The views expressed in this publication do not necessarily reflect those of IUCN.

Published by: IUCN/SSC Reintroduction Specialist Group & Environment Agency-Abu

Dhabi Copyright: © 2018 IUCN, International Union for Conservation of Nature and Natural

Resources Reproduction of this publication for educational or other non-commercial

purposes is authorized without prior written permission from the copyright holder provided the source is fully acknowledged.

Reproduction of this publication for resale or other commercial purposes is

prohibited without prior written permission of the copyright holder. Citation: Soorae, P. S. (ed.) (2018). Global Reintroduction Perspectives: 2018.

Case studies from around the globe. IUCN/SSC Reintroduction Specialist Group, Gland, Switzerland and Environment Agency, Abu Dhabi, UAE. xiv + 286pp.

6th Edition ISBN: 978-2-8317-1901-6 (PDF) 978-2-8317-1902-3 (print edition) DOI: https://doi.org/10.2305/IUCN.CH.2018.08.en Cover photo: Clockwise starting from top-left:

I. Reticulated python, Singapore © ACRES II. Trout cod, Australia © Gunther Schmida (Murray-Darling Basin

Authority) III. Yellow-spotted mountain newt, Iran © M. Sharifi IV. Scimitar-horned oryx, Chad © Justin Chuven V. Oregon silverspot butterfly, USA © U.S. Fish and Wildlife Service VI. Two-colored cymbidium orchid, Singapore © Tim Wing Yam VII. Mauritius fody, Mauritius © Jacques de Spéville

Cover design & layout by: Pritpal S. Soorae, IUCN/SSC Reintroduction Specialist Group Printed by: Arafah Printing Press LLC, Abu Dhabi, UAE Download at: www.iucnsscrsg.org www.iucn.org/resources/publications

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Reintroduction of the Telfair’s skink to Gunner’s Quoin, Mauritius

Nik C. Cole1, Rouben Mootoocurpen2, Martine Goder3, Vishnu Bachraz4, Vikash Tatayah5 & Carl G. Jones6

1 - Islands Restoration Manager, Durrell Wildlife Conservation Trust, Les Augrès Manor, Trinity, Jersey JE3 5BP & Mauritian Wildlife Foundation, Grannum Road,

Vacoas, Mauritius nik.cole@durrell.org 2 - Islands Restoration Assistant Coordinator, Mauritian Wildlife Foundation,

Grannum Road, Vacoas, Mauritius 3 - Islands Restoration Senior Coordinator, Mauritian Wildlife Foundation,

Grannum Road, Vacoas, Mauritius 4 - National Parks and Conservation Service, Reduit, Mauritius

5 - Conservation Director, Mauritian Wildlife Foundation, Grannum Road, Vacoas, Mauritius

5 - Scientific Director, Durrell Wildlife Conservation Trust, Les Augrès Manor, Trinity, Jersey JE3 5BP & Mauritian Wildlife Foundation, Grannum Road,

Vacoas, Mauritius Introduction The Vulnerable (IUCN) Telfair’s skink (Leiolopisma telfairii) is the sole surviving member of a unique Mascarene genus of large, terrestrial and omnivorous lizards. Once widespread throughout Mauritius and offshore islands, Telfair’s skinks became restricted to Round Island (219 ha, 20 km northeast of Mauritius) from the mid-1800s, representing the only suitable location not colonised by invasive mammalian predators, particularly rats (Rattus norvegicus and/or R. rattus). However, from the early 1800s introduced goats (Capra hircus) and rabbits (Oryctolagus cuniculus) decimated Round Island’s hardwood and palm-rich habitat, threatening the survival of Telfair’s skinks and other endemic reptiles (Cheke & Hume, 2008). To mitigate extinction risk, a captive assurance population was established from 1976 at Jersey Zoo, Round Island’s introduced herbivores were eradicated by 1986 and invasive mammals (predators and herbivores) were eradicated from neighboring islands by 1998, opening them for reptile reintroductions (Cheke & Hume, 2008). The islands were reviewed as possible reintroduction sites and Gunner’s Quoin (70 ha, five km north of Mauritius) was selected. Gunner’s Quoin was one of the last locations outside of Round Island to maintain Telfair’s skinks;

Telfair's skink © Nik Cole

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the cause of their loss had been removed in the 1990s and supported a suitable prey base and structural habitat required by the skinks. Goals x� Goal 1: Re-establish a self-sustaining population of Telfair’s skinks on

Gunner’s Quoin. x� Goal 2: The reintroduction does not compromise the health condition of the

Telfair’s skinks. x� Goal 3: The reintroduced Telfair’s skink population shares the same genetic

diversity as Round Island. x� Goal 4: Gunner’s Quoin’s native resident reptile populations remain robust

following the reintroduction of the Telfair’s skink. x� Goal 5: Following the successful reintroduction of Telfair’s skinks, continue to

rebuild Gunner’s Quoin’s reptile community with the reintroduction of the skink’s predator, the Endangered (IUCN) Round Island keel-scaled boa (Casarea dussumieri).  

Success Indicators x� Indicator 1: Telfair’s skinks reach their predicted carrying capacity on Gunner’s

Quoin within 10 years. x� Indicator 2: Reintroduced Telfair’s skinks maintain healthy body-condition

scores and remain free from novel parasites and disease. x� Indicator 3: Allelic diversity and heterozygosity within the reintroduced skink

population is the same as the source population, with no evidence of bottlenecks or inbreeding. 

x� Indicator 4: The relative abundances of the four native lizard species on Gunner’s Quoin does not decline below pre-Telfair’s skink release abundances. 

x� Indicator 5: Round Island keel-scaled boas are reintroduced to Gunner’s Quoin. 

Project Summary Feasibility: The overall objective of the reintroduction project was to rebuild the reptile community on the closed Island Nature Reserve, Gunner’s Quoin, and reduce extinction risks for Round Island’s reptiles. Between 2002 and 2006, Gunner’s Quoin’s suitability was assessed and Telfair’s skinks identified as the priority species for reintroduction (Bloxam, 1982; Jones, 1993; Cole et al., 2009). By 2006, Gunner’s Quoin was free from invasive predators, relatively safe from anthropogenic disturbances, offered suitable structural habitat and food resources. Robust populations of small endemic reptile species had survived and recovered from previous disturbances on Gunner’s Quoin and were predicted to withstand the Telfair’s skink reintroduction (Cole et al., 2009). The capacity of relevant stakeholders to undertake the reintroduction and monitoring was assessed, training needs and required external expertise were identified and project partners selected. The feasibility of translocation from Round Island was assessed; determining age, gender, health and disease risk assessment, distribution and planning selection for translocation, skink abundance and release size, timing and method of translocation and release, modes of transport, biosecurity, permissions, ethical review, funding requirements and post

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translocation survey and monitoring methods and protocols. Population viability models were developed from wild and captive Telfair’s skink data to predict the impact of removing skinks from Round Island for translocation and probabilities of survival and population growth post release on Gunner’s Quoin. Implementation: In 2005, the Government of Mauritius granted permission to start rebuilding Gunner’s Quoin’s reptile community, with the initial reintroduction of Telfair’s skinks. The translocation, monitoring and survey protocols were established. In 2006, the Durrell Wildlife Conservation Trust, Mauritian Wildlife Foundation and the National Parks and Conservation Service, with support from the University of Bristol and International Zoo Veterinary Group were granted Darwin Initiative funding (Ref:15038), with additional funding from the Government of Mauritius for the translocation and monitoring over three years (Cole et al., 2009). This coincided with training of Mauritian staff to conduct the translocations and monitoring, with the establishment of 72 permanent survey transects and 8 km of access paths on Gunner’s Quoin to monitor the resident fauna and flora, the translocated reptiles and to conduct frequent biosecurity checks. In February 2007, 250 (83 male, 153 female & 14 sub-adult) Telfair’s skinks were selected from Round Island and translocated by helicopter for hard release in pre-selected locations of suitable habitat across Gunner’s Quoin. Each released skink was fitted with a Passive Integrated Transponder (PIT) tag for individual recognition, permitting post-release monitoring of abundance, apparent survival, recruitment and dispersal. The national media (newspapers, radio and televised news broadcasts) were utilized and workshops with the Police and National Coast Guard were conducted to sensitize island users and enforcement agencies of the project and the protected status of Gunner’s Quoin to try to reduce trespassing and resultant human induced impacts. From 2008, with agreement and support of the Government of Mauritius, the project partners started to seek additional funding to continue the project long-term and develop additional research support through academic partners. Post-release monitoring: For the first three years, seasonal (summer and winter) post-release monitoring consisted of capture mark recapture (CMR) methods to determine Telfair’s skink abundance, apparent survival, recruitment and dispersal (with all newly discovered skink being PIT tagged). Monitoring also involved habitat and dietary utilization to determine impact upon the resident species; health and disease comparisons to Round Island; relative abundance estimates of invertebrates, vertebrates and key plant species; and biosecurity

Gunner's Quoin © Nik Cole

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checks to detect and remove invasive species incursions. Since then CMR, relative abundance estimates of vertebrates and health surveys have been conducted annually (Summer), but biosecurity checks have continued biannually. Post release survival, recruitment and dispersal has been high. No novel diseases or parasites have been found in the source or translocated reptile populations and the reintroduced skinks have remained healthy with higher than average body condition scores. In 2013, no evidence of genetic bottlenecking or inbreeding was found in the Gunner’s Quoin population and allelic diversity and heterozygosity was no different to Round Island (Cox, 2013). Dietary work demonstrated that Telfair’s skinks were consuming native and introduced species as predicted, but there have been no significant declines in native resident species to date. However,

some introduced species consumed by the skink have declined, such as the wasp (Polistes hebraeus), once abundant it has not been detected on the island since 2014. With a readjustment of the skinks’ predicted carrying capacity following habitat specific abundance estimates on Round Island the observed growth in skink abundance on Gunner’s Quoin has been similar to what was predicted. The skinks reached their carrying capacity in 2014, and their abundance is currently estimated at 14,297 individuals (±95%CI: 10,272 - 20,514), a 31.2% increase on the global population. Given the growth of the skink population, its native predator, the Round Island keel-scaled boa was successfully reintroduced between 2012 and 2014 and the boa population is growing. Major difficulties faced x� Access to Gunner’s Quoin and poor survey conditions in winter meant that

only thorough summer surveys could be continued. x� A high changeover in staff meant that capacity building has been ongoing

limiting core surveys to just a couple of staff. x� Despite being an Island Nature Reserve with prohibited access to the public,

Gunner’s Quoin continues to be frequently trespassed, leading to littering, burning, trampling, poaching and species introduction, such as the Australian redback spider (Latrodectus hasseltii) that took two years to eradicate. The risks of invasive predator incursion remains an issue.

x� Lack of capacity within Mauritius for reptile disease screening, requiring the lengthy and costly process of sending samples overseas.

x� Public support for reptile conservation and widespread opinions for reptiles remains low, despite extensive sensitization of their importance to the Mauritian ecosystems and regional biodiversity.

PIT tagging skinks © Nik Cole

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Major lessons learned x� Ensuring partners are made up of government agencies, non-government

organizations and academic institutes to facilitate permission and support, with organizational flexibility and cutting edge expertise.

x� Understanding the critical needs of the species and using expert opinion where there are gaps in the scientific literature to make, then test and adapt management decisions.

x� Using, testing and adapting population viability models to predict and test outcomes and plan further actions.

x� Although the project was conceptualized externally, what has made this project successful has been the ongoing building of host country capacity to lead this project with external support.

x� Ensuring long-term financial support to learn, develop, manage and generate buy-in from all partners.

Success of project

Reason(s) for success/failure: x� Good understanding of the species ecology and behavior. x� Ensuring that the threats to the survival of the species were no longer present. x� Having a vision that focuses on species to rebuild ecosystems. x� Long-term commitment of partners and high level of monitoring. x� Developing partnerships between Government agencies, NGOs and academic

institutes to meet the skill sets required to ensure success.  References Bloxam, Q.M.C. (1982) The feasibility of reintroduction of captive-bred Round Island skink Leiolopisma telfairii to Gunner's Quoin. Dodo-Journal of the Wildlife Preservation Trusts 19: 37-41. Cheke, A.S. & Hume, J.P. (2008) Lost land of the Dodo: an ecological history of Mauritius, Réunion & Rodrigues. A&C Black, London. Cole, N., Jones, C.G., Buckland, S., Jhumka, Z., Mootoocurpen, R., Tatayah, V., Bachraz, V., Nundlaul, V. & Roopa, P. (2009) The reintroduction of endangered Mauritian reptiles. Unpublished report, Mauritian Wildlife Foundation, Vacoas, Mauritius. Cox, S. (2013) Microsatellite primer development and genetic assessment of a translocated population of Telfair’s skinks (Leiolopisma telfairii). BSc thesis, Cardiff University, UK. Jones, C.G. (1993) The ecology and conservation of Mauritian skinks. Proceedings of The Royal Society of Arts and Sciences of Mauritius 5: 71-95.

Highly Successful Successful Partially Successful Failure

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