An investigation into declining skink populations and their behavioural responses to introduced mammalian predators Christina Terra Dumont Masters of Science in Ecology School of Biological Sciences, University of Canterbury Te Whare Wānanga o Waitaha 2015 Table of Contents Acknowledgments ......................................................................................................................... 1 Abstract .......................................................................................................................................... 2 Chapter 1: General Introduction ................................................................................................ 4 Effects of invasive predators on reptiles ..................................................................................... 4 The effect of introduced mammalian predators on New Zealand reptiles .................................. 7 Study species ............................................................................................................................. 10 Northern grass skink .............................................................................................................. 10 Speckled skink ....................................................................................................................... 10 Spotted skink ......................................................................................................................... 11 Glossy brown skink ............................................................................................................... 11 Outline of thesis ........................................................................................................................ 12 Tables ........................................................................................................................................ 14 Chapter 2: Life history traits of speckled, northern grass and spotted skinks in the St. Arnaud area, New Zealand; with a focus on speckled skinks ................................................ 16 Abstract ..................................................................................................................................... 16 Introduction ............................................................................................................................... 16 Methods ..................................................................................................................................... 18 Study area .............................................................................................................................. 18 Life history traits ................................................................................................................... 18 Trapping methods .................................................................................................................. 19 Statistical analyses ................................................................................................................. 20 Results ....................................................................................................................................... 21 Northern grass skinks ............................................................................................................ 21 Speckled skinks ..................................................................................................................... 22 Spotted skinks ........................................................................................................................ 23 Discussion ................................................................................................................................. 23 Northern grass skinks ............................................................................................................ 23 Speckled skinks ..................................................................................................................... 25 Spotted skinks ........................................................................................................................ 26 Recapture rates ...................................................................................................................... 26 Conclusion ................................................................................................................................. 27 Figures and Tables .................................................................................................................... 28 Chapter 3: Slithering away - a decade of mammalian predator trapping has not resulted in recovery of native skink populations......................................................................................... 39 Abstract ..................................................................................................................................... 39 Introduction ............................................................................................................................... 39 Methods ..................................................................................................................................... 42 Statistical analyses ................................................................................................................. 44 Results ....................................................................................................................................... 45 Long term population study (2002 – 2012) ........................................................................... 45 Recruitment ........................................................................................................................... 47 Lake Station, a comparison with 1995 .................................................................................. 47 Weather .................................................................................................................................. 47 Discussion ................................................................................................................................. 47 Mammalian predator control and skink abundance ............................................................... 47 Recruitment ........................................................................................................................... 49 Mammalian predator and skink population dynamics ........................................................... 49 Lake Station, a comparison with 1995 .................................................................................. 51 Alternative hypotheses for the decrease in skink abundance ................................................ 52 Conclusion ................................................................................................................................. 53 Figures and Tables .................................................................................................................... 55 Chapter 4: The importance of sub-lethal predation: introduced mammalian predators cause a decline in the body condition of native skinks ............................................................ 64 Abstract ..................................................................................................................................... 64 Introduction ............................................................................................................................... 65 Methods ..................................................................................................................................... 68 Statistical analyses ................................................................................................................. 70 Results ....................................................................................................................................... 70 Body condition ...................................................................................................................... 71 Caudal autotomy .................................................................................................................... 72 Mites ...................................................................................................................................... 72 Discussion ................................................................................................................................. 72 Body condition ...................................................................................................................... 72 Caudal autotomy .................................................................................................................... 75 Chigger mite load .................................................................................................................. 76 Conclusion ................................................................................................................................. 77 Figures and Tables .................................................................................................................... 79 Chapter 5: What’s that smell? Do New Zealand northern grass and glossy brown skinks avoid the scent of introduced rats or hedgehogs? .................................................................... 90 Abstract ....................................................................................................................................