Kent Academic Repository Full text document (pdf) Citation for published version Turner, Helena Summers (2018) Population Status and Conservation of the Critically Endangered Bermuda Skink. Doctor of Philosophy (PhD) thesis, University of Kent,. DOI Link to record in KAR https://kar.kent.ac.uk/84133/ Document Version UNSPECIFIED Copyright & reuse Content in the Kent Academic Repository is made available for research purposes. Unless otherwise stated all content is protected by copyright and in the absence of an open licence (eg Creative Commons), permissions for further reuse of content should be sought from the publisher, author or other copyright holder. Versions of research The version in the Kent Academic Repository may differ from the final published version. Users are advised to check http://kar.kent.ac.uk for the status of the paper. Users should always cite the published version of record. Enquiries For any further enquiries regarding the licence status of this document, please contact: [email protected] If you believe this document infringes copyright then please contact the KAR admin team with the take-down information provided at http://kar.kent.ac.uk/contact.html Population Status and Conservation of the Critically Endangered Bermuda Skink Heléna Summers Turner A thesis submitted for the degree of Doctor of Philosophy in Biodiversity Management Durrell Institute of Conservation and Ecology School of Anthropology and Conservation University of Kent September 2018 Word Count: 52,608 Population Status and Conservation of the Critically Endangered Bermuda Skink Heléna Summers Turner Supervised by: Professor Richard A. Griffiths Durrell Institute of Conservation and Ecology (DICE), School of Anthropology and Conservation, University of Kent, Canterbury, UK Dr. Gerardo Garcia Chester Zoo, Cedar House, Upton by Chester, Chester, UK Dr. Mark E. Outerbridge Department of Environment and Natural Resources, Government of Bermuda, Bermuda AUTHOR’S DECLARATION I, Helena S. Turner declare that this thesis has been composed solely by myself with the incorporation of suggestions, feedback and editorial amendments made by Richard A. Griffiths, Mark E. Outerbridge and Gerardo Garcia, and that it has not been submitted, in whole or in part, in any previous application for a degree. Except where states otherwise by reference or acknowledgment, the work presented is entirely my own. The text does not exceed 100,000 words and meets the formatting guidelines of the University of Kent. Chapter 1: HST wrote the chapter. Comments and feedback were provided by RAG. Chapter 2: Analysis and writing: HST; experimental and statistical design: HST and RAG; field work: HST, RAG, MEO and GG; revisions: RAG, GG and MEO. All authors contributed critically to the drafts and gave final approval for publication. This chapter was published in Oryx. Chapter 3: Analysis and writing: HST; experimental and statistical design: HST and RAG; field work: HST, RAG, and MEO; revisions: RAG, GG and MEO. Chapter 4: Analysis and writing: HST; experimental and statistical design: HST and RAG; field work: HST, RAG, MEO and GG; revisions: RAG. Additional data provided by R. Wingate, A. Raine, and M.P. Hammond. Chapter 5: Analysis and writing: HST; experimental and statistical design: HST and RAG; field work: HST, RAG, MEO and GG; revisions: RAG. Additional data provided by R. Wingate, A. Raine, M.P. Hammond, J. Davenport, A. Glasspool and M. Outerbridge. Chapter 6: HST wrote the chapter. Comments and feedback were provided by RAG. Additional comments were provided by the thesis examiners. I hereby declare that there were no competing interests on behalf of all co-authors. Any associated dataset and code will be made available through online repositories at the time of chapter publications. Signed: Date: 20/09/20 iii ACKNOWLEDGEMENTS I would like to express my gratitude to all those who have supported and helped me during my PhD study. My deepest gratitude goes first and foremost to Professor Richard Griffiths, my supervisor, for his patience, encouragement and guidance to help me grow as a researcher. I would also like to thank Dr. Gerardo Garcia as without his support my PhD would never have taken shape and thanks to you, I had enough data for a second PhD with all your extra suggestions. A special thank you to Dr. Mark Outerbridge and Jeremy Maderios without whom my fieldwork would not have been possible. I am grateful for all the time you spent sharing your knowledge about Bermuda, and the valuable suggestions on my study. I am also deeply grateful to you and the Government of Bermuda’s Department of Environment and Natural Resources for accommodation on Nonsuch Island for the duration of my fieldwork, for transport into the field and allowing me to continue collecting data (even after losing two boats, destroying a kayak and getting stranded on Horn Rock). I have no doubt Jeremy will continue to tell tour groups on Nonsuch Island about the ‘crazy skink researcher!’ I am also thankful to Alison Copeland, Miguel Meijas and Nesta Wellman who were great hosts while in Bermuda and helped me out on numerous occasions. I would particularly like to express my sincere gratitude to Rebecca, Felicity, William, Rachel and Ubu Lawrence whom I cannot thank enough for their kindness and welcoming me into their home, and to Lyn Pantry for that time I was in desperate need of a hot shower and pizza. And finally a massive thank you to everyone that assisted me in the field (Mark Outerbridge, Alison Copeland, Jeremy Maderios, Richard Griffiths, Gerardo Garcia, Miguel Meijas, Nesta Wellman, Jim Labisko, Stephanie Clayton-Green, Dylan Muldoon, Nathan Wright, Luiza Passos, Dario D’Afflitto, Jack Carney, Mandy Shailer, Peter Drew, Monika Alonso, Russ Frith, Kirk Trott, Robin Marirea, J.P. Rouja, Phillipe Rouja, Lynne Thorne) that made the boating adventures, long hours of extreme heat and humidity, rotten fish and prickly pear spikes bearable. I wish to thank Professor Jim Groombridge and all my DICE colleagues who took the time to help me and provide advice: Izabela Barata, Andrew Buxton, Debbie Fogell, Hazel Jackson, iv Simon Tollington, Jim Labisko and Jamie Sells. I am also grateful to Dr. Rachel McCrea, Dr. Diana Cole, Dr. Eleni Matechou who assisted in data analysis and modelling construction during various statistics workshops. I would additionally like to thank John Davenport and Zoe G. Davies for their valuable comments and recommendations. Lastly my thanks would go to my wonderful family for their whole-hearted support for the past four years. I couldn’t have done it without you all! This research was supported by several funders and collaborators that I am extremely grateful to June Summers Shaw, Chester Zoo, The States of Jersey, the British Herpetological Society and the Bermuda Zoological Society that supported this study. Thanks also to the Government of Bermuda’s Department of Environment and Natural Resources, Professor Richard Preziosi at Manchester Metropolitan University (previously at the University of Manchester) and Dolphin Quest for providing additional field supplies and equipment. (Photo credit: Turner, H. 2016) v ABSTRACT Global biodiversity is currently facing the sixth mass extinction with species disappearing at a rate 100 times background levels - mostly driven by anthropogenic pressures. Island species are often evolutionarily distinctive and are highly vulnerable to novel disturbances due to having small geographic ranges. The isolation of Bermuda has led to the evolution of a unique ecosystem with many endemic species. However, native species across Bermuda have become especially vulnerable ever since human colonisation, due to habitat loss and destruction, and predation and competition by several introduced species. The Bermuda skink (Plestiodon longirostris) was once widespread and commonly found along stone walls and cedar groves across Bermuda. By 1965, the population had become extremely fragmented and was declining across Bermuda and its offshore islands. This thesis investigates the threats to the Bermuda skink, listed as Critically Endangered by the International Union for the Conservation of Nature. Surveys were conducted between 2015 and 2017 across Bermuda to (1) estimate population parameters such as abundance, capture and survival probabilities; (2) estimate occupancy, colonisation, extinction and detection rates; (3) determine if skink sub-populations are morphologically different; and (4) compare the body condition between sub-populations that may provide warning signs of issues in the environment such as changes in the level of competition, predation or available habitat. Additionally, recommendations are provided for the conservation management and recovery of this species. From capture-mark-recapture surveys and subsequent robust design modelling, it was found that the two largest populations fluctuated in size at both sites over the three-year survey period, and are imminently threatened by increasing anthropogenic activities, invasive species, and habitat loss in Bermuda. Using dynamic occupancy modelling across Bermuda, skinks were detected at 13 locations. The probability of detection was higher on island sites and with the presence of seabirds, prickly pears and coastal habitat. However, skinks were unlikely to be detected at sites with cat and rat predators. We demonstrate that morphological diversification has occurred, possibly in response to isolation and changes to habitat and predator levels over time, especially