WHO'S ON THE MENU: MARSUPIAL CARNIVORE FEEDING ECOLOGY AND EXTINCTION RISK Thesis submitted by ARIE TTARD M A For the Degree of Doctor of Philosophy in the School of Biological, Earth & Environmental Sciences Faculty of Science March 2013 THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Family name: Attard First name: Marie Other name/s: Rosanna Gabrielle Abbreviation for degree as given in the University calendar: PhD School: School of Biological, Earth and Environmental Sciences Faculty: Faculty of Science Title: Who's on the menu: marsupial carnivore feeding ecology and extinction risk Abstract The aim of this thesis is to assess the role of diet in the extinction of Australia's iconic marsupial carnivore, the thylacine (Thylacinus cynocephalus) in Tasmania. Herein, we present two novel techniques to address fundamental questions regarding their maximum prey size and potential competition with sympatric predators. Three-dimensional computer models of the thylacine skull were used to assess their biomechanical limitations in prey size within a comparative context. This included living relatives from the family Dasyuiridae as well as a recently recovered fossil, Nimbacinus dickoni, from the family Thylacindae. Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) of tissues from thylacine and potential prey species were used to assess the thylacine’s dietary composition. Furthermore, we integrate historical and recent marsupial carnivore stable isotope data to assess long-term changes in the ecosystem in response to multiple human impacts following European settlement. Our biomechanical findings support the notion that solitary thylacines were limited to hunting prey weighing less than their body mass. This concurs with our stable isotope results, which suggest medium-sized mammals were a major element of thylacine subsistence in Tasmania. Prey species may have included the common wombat (Vombatus ursinus), red- necked wallaby (Macropus rufogriseus) and Tasmanian pademelon (Thylogale billardierii). These species fall within the expected size range of prey needed to sustain this large carnivore. Competition among thylacines and sympatric marsupial carnivores in Tasmania was suggested by similarities in their prey size and trophic niche. If interspecific competition had been a major limiting factor for the small thylacine population, encounters with smaller predators were possibly reduced by occupying different habitats, as indicated by differences in predator δ13C values. The century-long change in Tasmanian devil and spotted-tailed quoll 13C values suggests a change in vegetation in the areas typically inhabited by these species, or more likely indicates the movement of these top predators away from traditional open grassland, mosaic habitats to more densely forested habitats due to habitat loss and fragmentation. These species also displayed temporal changes in their δ15N values, which may be attributed changing prey availability or changes in the source nitrogen at the base of the food. This thesis provides a framework to test the resilience of marsupial carnviores to anthropogenic impacts in light of their biological traits and may be used to improve the conservation of large predators. Declaration relating to disposition of project thesis/dissertation I hereby grant to the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all property rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstracts International (this is applicable to doctoral theses only). 28/03/2013 ……………………………………………… ……………………………………..……… .……………………...…….… Signature Witness Date The University recognises that there may be exceptional circumstances requiring restrictions on copying or conditions on use. Requests for restriction for a period of up to 2 years must be made in writing. Requests for a longer period of restriction may be considered in exceptional circumstances and require the approval of the Dean of Graduate Research. FOR OFFICE USE ONLY Date of completion of requirements for Award: COPYRIGHT STATEMENT 'I hereby grant the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstract International (this is applicable to doctoral theses only). I have either used no substantial portions of copyright material in my thesis or I have obtained permission to use copyright material; where permission has not been granted I have applied/will apply for a partial restriction of the digital copy of my thesis or dissertation.' Signed~ ······ · ··························· ·· ························ Date .9.~/q?/?~. ~ -~ - .......................................................... AUTHENTICITY STATEMENT 'I certify that the Library deposit digital copy is a direct equivalent of the final officially approved version of my thesis. No emendation of content has occurred and if there are any minor variations in formatting , they are the result of the conversion to digital format.' Signed~ ···· · ······ · · · ···· · ·· · ······ · ········ · ·· · ···· · ·· · ·· · ········ Date .9.~/9.?/?..QJ4 .......................................................... .. MARSUPIAL CARNIVORE FEEDING ECOLOGY AND EXTINCTION RISK ORIGINALITY STATEMENT ‗I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation and linguistic expression is acknowledged.‘ Marie Attard 28 March 2013 i Acknowledgements ACKNOWLEDGEMENTS Completing my PhD was truly a marathon event, and I would not have been able to accomplish this journey without the aid and support of countless people over the past four years. Foremost, I would like to express my sincere appreciation to my joint- supervisors, Tracey Rogers and Steve Wroe for their continuous support and excellent guidence on how to negotiate the academic world. Tracey's love for all things mammals, insightful ideas and skill in communicating science has been a great asset to the project and has helped develop my skills as a researcher. Steve's vast knowledge of marsupial carnivores and all-round ingenuity and kindness has been an inspiration to me that I will never forget. Uphar Chamoli, William Parr, Toni Ferrara, Laura Wilson and Natalie Rogers from the Computational Biomechanics research group have provided many stimulating discussions and a never ending level of support. I would especially like to thank Uphar Chamoli for generously giving up his time to help me with various problems over the years relating to my biomechanics research. I have never seen anyone as skilled or quick to tackle problems as Uphar, and I know he will go a long way in his career. I would also like to thank my colleagues in the Rogers' research group, Marlee Tucker, Naysa Balcazar-Cabrera, Jeffery Fung, Jessica Meade, and earlier on Tiffanie Nelson, Nadine Constantinou, Lisa Steindler, Benjamin Jeggle, Tempe Adams and Michaela Ciaglia. They have provided me with many good memories and have brightened up our lab with their humour and fantastic baking skills. I also thank my fellow postgraduate colleagues for sharing with me the battles of PhD life and joy in finally getting our research out there. Together we have proved that no matter how small (or dead) the research subject, our research matters. I would particularly like to thank Alan Kwok, Samantha Travers, Joanne Ocock, Celine Steinfeld and Stefani Daryanto for their friendship and providing me with a listening ear in a difficult situation. ii MARSUPIAL CARNIVORE FEEDING ECOLOGY AND EXTINCTION RISK I would like to acknowledge the generosity of various museums for opening the doors to their collection and providing tissues from their precious specimens. I hope my research is able to enlighten others about the value of museum collections, which is usually underestimated. I would like to personally thank Darrin Lunde (American Museum of Natural History), Gerald Legg (Booth Museum), Matt Lowe (Cambridge Zoological Museum), Clare Brown (Leeds City Museum), Lawrence Heaney and William Stanley (Field Museum of Natural History), Virginie Volpato (Forschungsinstitut & Schaumuseum Senckenberg),