![]() ![]() Hibernating as early as June seems preposterous. Calendar dates vary somewhat within cohorts, across years, and with geographic location, but everywhere in every year, adult males, adult females, and juvenile females enter hibernation in the summer months. ![]() These dates are June 22 for adult males, July 4 for adult females, August 10 for juvenile females, and October 15 for young males. Astonishingly, the majority of ground squirrels start hibernation when temperatures are increasing over summer.įrom 25 years of censusing a population of Richardson’s ground squirrels near Lethbridge, I calculated the average dates that are most representative of the onset of hibernation in a typical year in southern Alberta. ![]() Juvenile females do not hibernate for another five to six weeks, and a further two months later the juvenile males finally enter hibernation. The first to hibernate are adult males, followed by adult females about two weeks later. In combination, these techniques ensure that I always know who is who and which individuals are present or absent.ĭaily censuses quickly reveal four groupings of squirrels with dramatically different times of entry into hibernation. A unique mark dyed on the fur facilitates identification for observational purposes, but requires renewal after each moult. A uniquely numbered earring in each ear provides lifetime identification, but the numerals are too small to be readable at a distance. With no natural identifying features comparable to whisker patterns in lions or dorsal fin shape in orcas, I depend on a two-step identification system for my studies. Richardson’s ground squirrels can tell each other apart by a combination of odour and behaviour, but to us they all look alike. Teasing apart who hibernates when requires daily censusing of individually recognizable animals. Winter does not last that long, so what accounts for such extraordinarily long hibernation seasons? Long-term studies reveal that juvenile males do indeed hibernate for four months, but their sisters, mother, and father all spend seven to eight months in hibernation. However, that perception is only partially accurate. I soon learned that Richardson’s ground squirrels are regularly seen above ground during daylight hours for seven to eight months of the year, but rarely from late October through late February, generating the perception that they hibernate for a four-month period encompassing winter. ![]() So, is life as an Arctic ground squirrel enviable? I’m not sure-you’ll have to ask the squirrels.When I came to Canada from Australia years ago, I had never heard of Richardson’s ground squirrels, not even by their more vernacular name of “gopher.” To me, these prairie residents were exotic animals, and I wanted to know about them. When summer ends, the squirrel holds up in its burrow again, and the whole process starts over. But every few weeks, the squirrels shimmy, shiver, and shake, for hours at a time, warming themselves up just enough to stay alive.Īs spring arrives, the Arctic ground squirrel stops hibernating: Males first, and three weeks later, females. Not only is that below freezing, it’s the lowest recorded body temperature of any mammal! This feat is called “supercooling.” Entire organs slow, or shut down. Emphasis on the extreme: As Arctic ground squirrels hibernate, their body temperature drops to 28 degrees Fahrenheit. Instead, hibernation conserves energy through extreme inactivity. Though hibernation looks a lot like sleep, it’s not the same thing. Come fall, they lie down in their burrows, lowering their metabolic rate and surviving off accumulated body fat. To avoid starvation, lack of resources, and cruel weather, Arctic ground squirrels eat so much they nearly double their body weight. But these squirrels aren’t taking cover for the fun of it: Their survival of the long cold season depends on their ability to hibernate. If you detest snow and ice, that set-up might sound pretty appealing. Here are the pros: you’d hibernate during winter-all eight months of it. And the summer, when you’d be at your most active, is rather short. You’d be popular prey for local predators. Let’s have a debate: would you want to be an Arctic ground squirrel? Here are the cons: you’d live in the frigid tundra. ![]()
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