![]() ![]() This means that during these cold periods, there must have been greater seasonal permafrost thaw depths than there are today! During the cold glacial periods of the Ice Age, ground squirrels were able to live in areas in which they are absent today because of shallow permafrost. The discovery of ice age ground squirrel burrows and middens in the goldfields presents a counterintuitive puzzle. Arctic ground squirrels do not live in the areas around the Klondike goldfields today due to the proximity of the permafrost to the surface there-ground squirrels cannot dig through frozen ground and must have access to at least 100 centimetres of thawed ground to dig their hibernaculae. Today, arctic ground squirrel populations are quite restricted to isolated open ground in both southern and northern Yukon, but during the glacial periods of the Ice Age their range expanded into the Klondike goldfields in central Yukon. ![]() Their prehistoric burrows and nests, also called middens, can be found criss-crossing the permafrost bluffs of many placer mine gold mines. Ice age Arctic ground squirrel remains are common finds in the thick mud, or "muck", of the Klondike goldfields of Dawson City. Conveniently for scientists studying the ice age world, these adaptations for hibernation and seed caching have preserved an unprecedented record of the plant communities present during the Ice Age. To survive once they emerge from their dens in late April or early May, they make use of cached seeds and grasses from the previous fall. During hibernation, Arctic ground squirrels perform one of the most amazing feats of any living mammal-they allow their body temperature to drop below freezing to -2.9☌, warming up periodically through bouts of shivering. Arctic ground squirrels survive the long winter by hibernating for seven or eight months in dens, or hibernaculae, about 100 centimetres below ground surface. They live in large colonies of as many 50 individuals where they maintain extensive tunnel networks. They are commonly seen along roadsides throughout much of southern Yukon-including a unique population of jet-black Arctic ground squirrels that live along the Alaska highway south of Whitehorse, Yukon.Īrctic ground squirrels are well adapted for their Arctic world, particularly the cold glacial times when the Mammoth Steppe extended across Beringia. Today, these medium-sized rodents can be found beyond the treeline or in treeless clearings across the Circumpolar North, from Siberia to the Canadian Eastern Arctic. The oldest discovered Arctic ground squirrel remains have been found in Alaska and date back 1.8 to 2.5 million years. Ground squirrels first appeared in North America about 10 million years ago, but quickly expanded north and west into Eurasia. Of all the ice age animals still alive today, the Arctic ground squirrel has arguably taught us the most about the ice age world. ![]()
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