One of the last hopes that polar bears may be able to weather the changing climate and break-up of their icy habitat has just been dashed. The bears are facing longer periods without the sea ice on which they depend for hunting seals, and some spend the months between August and October on shore. The hope was that during ice-free months, when their primary food source is scarce, the bears could slow down their metabolism to winter hibernation levels without going to sleep - so-called "walking hibernation". But an analysis of 30 polar bears in the Beaufort Sea near Canada shows this isn't the case. The bears did slightly reduce their activity and body temperature in the lean months, but not enough to maintain body weight and improve their chances of survival. This is probably an emergency response to lack of food rather than a form of hibernation.
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