Nature's strategies: Squirrels with a rainy day fund

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Science  02 Mar 2018:
Vol. 359, Issue 6379, pp. 982
DOI: 10.1126/science.359.6379.982

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Organisms often face times when resources are scarce. To get by, the 13-lined ground squirrel, like many other creatures, stockpiles resources to use later. Scurrying around the South Dakota prairie, the ground squirrels mark the approach of winter by bingeing. By the time a squirrel holes up to hibernate, its weight will have soared by about 40%. But the tactic has downsides. A roly-poly rodent is easier prey for a hawk or coyote. The rainy day fund also can run out prematurely. So once a squirrel is nice and tubby, it enters hibernation, slashing its energy expenditure by 90%. Packing on the fat requires metabolic and behavioral adjustments. Although it develops some of the metabolic defects of type 2 diabetes, the animal isn't sick. And by spring, it is lean and spry and ready to begin the cycle again.