The current range of snowshoe hares in Wisconsin (gray), and areas of range contraction since 1980 (red).
The snowshoe hare is an ecologically and economically important native vertebrate whose southern range boundary terminates in central Wisconsin. Snowshoe hares serve as critical prey for many species of carnivores like bobcat, foxes, fishers, and raptors. To understand how snowshoe hare distribution in Wisconsin has responded to broad scale environmental changes in the past half century we implemented a systematic snow tracking survey across their historical range boundary. We only detected snowshoe hares at only 29 of 148 historical sites, and observed an average shift north of 29.5 km since 1980. We found that historical snowshoe hare presence was best explained by the distribution of forest cover, while patterns of extinction between 1980 and 2014 was primarily driven by a reduction in snow cover duration. The relationship between snowshoe hare extinction and reduced snow cover duration is likely the result of an increasing prevalence of phenotypic mismatch between a snowshoe hares seasonal coat color change and background snow conditions, a phenomenon documented elsewhere in their range. With the observed shifting mechanisms operating this range boundary, the distribution of snowshoe hares in Wisconsin has tracked the shifting paradigm of wildlife conservation. The historical range retraction was primarily driven by habitat, at that time when habitat loss was the most recognized threat by research biologists. More recently, however, as climate change has moved into the conservation spotlight, the range of snowshoe hares in Wisconsin has become increasingly limited by snow cover. Projections of future range show that snow cover loss will likely continue to drive a northward shift in this species’ distribution into the future, with implications for the entire northern forest community in the region.
This work was funded by the Wisconsin DNR.