Polar bear survival during summer

If you happen to be in the Arctic this summer polar bears (Ursus maritimus) can be spotted spending their time on the sea ice or on the shore in areas where ice has melted. While it is difficult to study the physiology of bears living on the ice, it had been hypothesized that bears living on shore experience a state similar to winter hibernation in which they attempt to decrease their energy expenditure when food resources are low. However, new research published in Science shows that bears living on the ice as well as those on shore experience some decrease in activity as well as body temperature while their energy expenditure is actually similar to that of animals that are fasting but not hibernating.

The research team enlisted help from the US Geological Survey, US Fish and Wildlife Service, two helicopters and an ice-breaking vessel to help capture and tag over two dozen polar bears as well as implant 17 bears with a probe that can measure body temperature. It took 36 days just to recapture the animals with the temperature probes!

With the Arctic ice beginning to melt earlier in the summer and also taking longer to freeze in the winter, these prolonged periods of ice melt may be a challenge to the animal's survival over time according to study co-author Merav Ben-David (University of Wyoming - Laramie).

Sources:

Whiteman JP, Harlow HJ, Durner GM, Anderson-Sprecher R, Albeke SE, Regehr EV, Amstrup SC, Ben-David M. Summer declines in activity and body temperature offer polar bears limited energy savings. Science, 349(6245), 295-298, July 2015.  
DOI: 10.1126/science.aaa8623

Image of a "shore" polar bear from National Geographic.