It's not easy to swim 175 km (109 mi.) when you're starving to death. It's not easy either to try to survive when you're shedding body weight at a rate of 1 kg (2.2 lbs.) a day. And it might be hardest...
The polar bears in Hudson Bay [Canada] are probably at the edge of the range at which they can survive right now, says Anthony Pagano, a research biologist with the U.S. Geological Survey and the lead author of the paper.
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