Derbyshire, Rachael
Appendix A8: (Supplementary Materials 8): Audio clip of kleptoparasitism (klepto_feed.wav)
Appendix A7: (Supplementary Materials 7): Lynx feeding (lynx_feeding.mp4)
Appendix A6: (Supplementary Materials 6): Squirrel kill (squirrel_kill_feed.wav)
Appendix A5 (Supplementary Materials 5): Chase and hare kill (harecall.wav)
Appendix A4 (Supplementary Materials 4): Feeding (feeding.wav)
Behavioural responses of Canada lynx (Lynx canadensis) to cyclic declines in the snowshoe hare (Lepus americanus)
Population cycles are characterized by predictable temporal oscillations in population size and are influenced by densities of both predators and prey. These oscillations are influenced by the predator functional response, i.e. the influence of prey density on predator kill rate. The Canada lynx (Lynx canadensis) is a predatory mammal with cyclic northern populations driven by snowshoe hare (Lepus americanus) density. Despite some understanding of the drivers of lynx cycles, we lack understanding of how lynx hunting behaviour, including kill site selection, is influenced by the spatio-temporal distribution of prey. These concepts are explored in chapter one of this thesis.
In chapter two, we (coauthors and I) built on work in Kluane region of the Yukon where lynx and hare populations have been tracked through several population cycles. Over six winters, we deployed GPS collars on >40 individual lynx, some of which were fitted with satellite transmitters, accelerometers, and audio recorders. We validated the use of these technologies for identifying hare kills with an accuracy of >87%. This validation is the foundation for chapter three of this dissertation.
In chapter three, we investigated the drivers of spatial variation in lynx kills. Using snow track transects through four winters of declining hare density, we developed a robust model of habitat-specific hare abundance over time. Using model predictions, in combination with lynx Utilization Distributions derived from GPS locations and related habitat associations, we determined the importance of hare abundance, lynx spatial use, and landscape characteristics such as vegetation density in determining patterns of lynx kills and space use. Lynx kill sites were most strongly predicted by lynx space use, followed by the relative abundance of hares, an index of tree cover density, and elevation. Lynx space use itself was not strongly predicted by hare relative abundance, but rather by a shift to the use of more open habitats when hares were abundant to higher use of denser habitats as hare populations declined; this apparently corresponded to temporal changes in hare distribution. This thesis helps to disentangle the drivers of spatio-temporal variation in predator foraging behaviour, with important implications for understanding predator-prey dynamics.
Author Keywords: animal behaviour, biologging, foraging, habitat selection, Lynx canadensis, predator-prey dynamics