FILE - This undated file photo released by the U.S. Fish and Wildlife Service shows a sow polar bear resting with her cubs on the pack ice in the Beaufort Sea in northern Alaska. Polar bears forced to... more 
FILE - This undated file photo released by the U.S. Fish and Wildlife Service shows a sow polar bear resting with her cubs on the pack ice in the Beaufort Sea in northern Alaska. Polar bears forced to swim longer distances because of diminished sea ice off Alaska’s coast may be paying a price in lost cubs or precious calories, according to a study by the U.S. Geological Survey. (AP Photo/U.S. Fish and Wild Life Service, Steve Amstrup, File) less 
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Associated Press | Photo By U.S. Fish and Wild Life Service, Steve Amstrup, File
Tue, Jul 19, 2011 11:33 PM EDT