Drivers of Hibernation Immergence in Wild Populations of Columbian Ground Squirrels (Urocitellus columbianus) in Relation to Climate Change
Scheuer, Maison E.
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Climate change has already been shown to have demonstrable effects on plant and animal phenology; however, most studies neglect the changes it may elicit on mammalian hibernation. Of the studies that do focus on mammalian hibernation, most are biased toward the end of hibernation – hibernation emergence- and reproduction. To shed some light on the effects that climate change may have on other vital periods of a hibernating animal's seasonal cycle, we studied what factors influence the start of hibernation - hibernation immergence - in a wild population of Columbian ground squirrels from multiple study sites in Alberta, Canada from 2009-2016. Squirrels were caught in live traps and collars containing temperature sensors were used to determine the physiological state at hibernation immergence. We found that temperature, sex, site, and an interaction between site and year significantly influenced the date of hibernation immergence in Columbian ground squirrels, and that precipitation and year did not. We observed no apparent annual trend in hibernation immergence date or temperature at the three study sites over the 8 years this study took place, suggesting that climate change has not yet caused a shift in phenology at the time of hibernation immergence. This study provides the first insight into variables that influence the timing of Columbian ground squirrel's hibernation immergence and how climate change affects the length of their active season. From these data, we can make inferences about how climate change will affect their growth, survival, and fitness.