Columbian ground squirrels are now surfacing from their winter hibernation in the foothills of Canada’s Rocky Mountains 10 days later than they did 20 years ago. These findings by a group of international researchers were published in the online edition of the journal Nature earlier this month. The delay is considered significant and is having an impact on how many female squirrels and their babies survive to the next spring.
In newspaper interviews this month, Jeffrey Lane, lead author of the new study, puts the squirrels’ delayed surfacing down to the increased frequency of late-spring snowstorms. Lane says that after studying a colony of Columbian ground squirrels for 20 years in Kananaskis Country’s Sheep River Park, the survival rate for female squirrels has dropped by one percent every year. Twenty years ago, 87 percent of the rodents survived the winter. Last spring, 67 percent survived.
According to the study, Columbian ground squirrels spend as much as three-quarters of the year sleeping in their burrows. Their three to four months of activity is highly regimented. Waking up 10 days later means that much less time to fatten up before hibernating again. And if food is less than ideal because dumps of late-spring snowfall have affected the vegetation, survival is harder.
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