Flatbacks and Foxes Using Cameras to Capture Sea Turtle Nest Predation
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Flatbacks and foxes: Using cameras to capture sea turtle nest predation by Joanne King Bachelor of Science (Environmental) A thesis submitted to the Murdoch University to fulfil the requirements for the degree of Bachelor of Science in Conservation and Wildlife Biology with Honours (H1150) in the discipline of Veterinary and Life Sciences Murdoch University, 2016 Author’s Declaration I declare that this thesis is my own account of my research and contains as its main content work which has not previously been submitted for a degree at any tertiary education institution. iii Abstract Flatback turtles ( Natator depressus ) are marine turtle species endemic to Australia. There is currently insufficient data to allocate a conservation status for this species by the International Union for Conservation of Nature (IUCN). Predation upon turtle nests is recognised as a key threatening process to marine turtle species (Commonwealth of Australia, 2003) along with a number of other key anthropogenic threats. The Pilbara region in north-west Western Australia has a number of regionally significant rookeries including the Mundabullangana (Munda) Rookery located on the mainland. Fox predation is known to occur at the Munda rookery however the predation rate and impact of predators disturbing nests is unknown. Physically observing turtle nests daily for signs of predation is time consuming and requires extensive resources to access remote locations. Camera and non-camera sites were installed at the time of oviposition by flatback turtles to monitor the entire incubation period. Daily observations were undertaken and χ² tests were applied to determine effectiveness of camera monitoring as opposed to physical observation and impacts upon nests. Foxes were found to be the primary predator of turtle nests at Munda rookery. The predation rate by foxes was found to be 26% at Munda rookery with 42% of predated nests predated more than once. Foxes were found to be a late term nest predators with 11 out of 19 nests predated in the period of time between post-hatching and pre-emergence. Cameras were found to be significantly better than physically observing turtle nests for incidents of predation. Cameras were also able to provide behavioural data on target species as well as identify avian and other native faunal predators of hatchlings. Predation of nests at Munda were significant and warrant the implementation of fox mitigation strategies and actions to protect nests. Cameras are a useful tool for monitoring turtle nesting beaches for predators, however, the research location, weather conditions and ease of accessibility are factors which need to be considered, as cameras do require more frequent cleaning in beach v environments than when located in less exposed sites and removal may be necessary during extreme weather events. vi Acknowledgements Firstly I would like to thank my supervisors Dr Peter Adams, Professor Trish Fleming, Dr Bill Bateman and Dr Scott Whiting. The guidance and support has been invaluable. In particular thank you to Trish for your time, effort and patience in walking me through statistics, and to Scott for coming out in the field and camping in the north-west November heat. I would like to thank Michael Thompson, owner of Mundabullangana station, for permission to access the rookery through your property. As well as station staff Meado, Phil and Gail for all your assistance and information provided throughout the project. I would like to thank the Department of Parks and Wildlife for providing the opportunity to undertake this project as an honours degree. In particular thank you to my work supervisor Rachael Marshall for your support and encouragement, of without which this study would never have happened. I would also like to acknowledge the North West Shelf Flatback Turtle Conservation Program for providing the funding to purchase the cameras used in this project. To volunteers Mick Davies and Clem Whittles a huge thank you. The camping conditions; the heat, flies, working during the nights and trying to sleep during the days were extremely challenging. Yet both of you met these challenges with good humour and came back for more. To Phil and Jenelle Paxman your enthusiasm and assistance in the field was fantastic, as were the treats, thank you Jenelle. To Pendoley staff and volunteers, especially Anna Vitenbergs, Anna and Tyrone, it was a pleasure to work alongside of all of you. A special thank-you to the two Anna’s, without your help components of this study would not have been achieved. Thank you to Margie Mohring and Jo Kuiper for providing feedback on my thesis. And finally, thank you to Alicia Whittington for all of your help and encouragement over the life of this study. vii Table of Contents Author’s Declaration .................................................................................................................................. iii Abstract ....................................................................................................................................................... v Acknowledgements ................................................................................................................................... vii Table of Contents ....................................................................................................................................... ix List of Figures .............................................................................................................................................. xi List of Tables ............................................................................................................................................. xiii Chapter 1 General introduction ........................................................................................................ 15 1.1 Background ...................................................................................................................... 15 1.2 Overall aim of this thesis .................................................................................................. 17 1.3 Thesis structure ................................................................................................................ 18 Chapter 2 Flatback turtle biology ..................................................................................................... 19 2.1 Population pressures and impacts on flatback turtles ..................................................... 22 2.1.1 Climate change/increasing temperatures .................................................................. 22 2.1.2 Commercial fishing ..................................................................................................... 23 2.1.3 Marine debris ............................................................................................................. 24 2.1.4 Habitat loss ................................................................................................................. 24 2.1.5 Industrial activities ..................................................................................................... 25 2.1.6 Lighting ....................................................................................................................... 25 2.1.7 Anthropogenic impacts .............................................................................................. 26 2.1.8 Predation .................................................................................................................... 26 2.2 The red fox in Australia .................................................................................................... 28 2.2.1 Predation monitoring of turtle nests .......................................................................... 30 Chapter 3 Impacts of fox predation upon sea turtle nests using remote cameras as a monitoring tool 33 3.1 Materials and Methods .................................................................................................... 34 3.1.1 Study site .................................................................................................................... 34 ix 3.1.2 Experimental approach .............................................................................................. 36 3.1.3 Statistical analyses ..................................................................................................... 44 3.2 Results ............................................................................................................................. 46 3.2.1 What is the predation rate of flatback turtle nests at Munda Rookery?................... 46 3.2.2 Does human and predator mediated disturbance impact on remaining eggs and hatchlings within the nest? ........................................................................................ 46 3.2.3 Are remote cameras more effective than direct observation to confirm predation events on monitored turtle nests? ............................................................................ 48 3.2.4 Are cameras a useful tool for capturing predator activities? .................................... 49 3.3 Discussion ........................................................................................................................ 55 3.3.1 What is the predation rate of flatback turtle nests at Munda Rookery?................... 55 3.3.2 What impacts occur to predated nest? ..................................................................... 56 3.3.3 Are remote cameras