Habitat overlap of Canada lynx and sympatric mesopredators increases following cyclical reduction in primary prey.

In multi-predator systems, niche expansion may increase habitat overlap among species and the potential for competitive or predatory interactions. The strength of those interactions is likely mediated by cyclic changes in prey availability. In the northern boreal and subboreal forests of Alaska and Canada, snowshoe hare populations cycle over an 8-11-year period and that variation can strongly influence the distribution and population dynamics of carnivores. We used camera traps to investigate the habitat use and overlap of lynx and sympatric mesopredators (coyote, fisher, wolverine) during two contrasting periods of hare abundance. Given optimal foraging theory and the relatively short interval between changes in prey abundance, we predicted that habitat overlap would increase during a low in hare abundance when Canada lynx and other mesopredators hunt alternative prey in varied habitats. We found that lynx occurrences mirrored the decrease in hares, while the occurrences of sympatric carnivore species increased during the low in hare abundance. Habitat overlap of lynx with other sympatric carnivores increased at a time of prey scarcity. Predator populations in subboreal forests may be in a dynamic state of habitat overlap dependent on cyclic prey abundance. Our results highlight the importance of long-term data and the consideration of natural cycles for interpreting broader scale questions about environmental disturbance and climate change.