Spatial variation in bioclimatic relationships for a snow-adapted species along a discontinuous southern range boundary

Documenting variation in the relationship between climate variables and species occurence at range boundaries can help reveal how species will respond to global climate change. We collected snowshoe hare (Lepus americanus) presence-absence data from snow-track surveys conducted in the U.S. states of Michigan and Wisconsin in winters from 2012-2014 at their southern range boundary in the region. A series of 125m transects were walked at each site within a week of fresh snowfall, and the presence or absence of snowshoe hare tracks on each transect was recorded. Data set also includes the variables mean 5-year snow cover duration, mean 5-year maximum temperature, and percentage forest cover at each site. Each variable was used in data analysis for the related paper to relate snowshoe hare occurrence to climate and land cover variables at the southern edge of their distribution. Snowshoe hares in the region occur in areas with longer snow cover duration and lower maximum temperatures but these relationships vary across the study area such that maximum temperature was positively correlated with snowshoe hare occurrence in the northern portion of the study area (Upper Peninsula of Michigan).

Methods
Sites were selected based off historical locations of snowshoe hares from a peer-reviewed manusript in Wisconsin, or hunter surveys in Michigan. Snow tracking surveys were performed at sites during winters 2012-13 and 2013-2014. A series of 125m transects were walked and we recoreded whether snowshoe hare tracks were present on each transect (Counts column).