"In one of the most dramatic signs ever documented of how shrinking Arctic sea ice impacts polar bears, researchers at the U.S. Geological Survey in Alaska have tracked a female bear that swam nine days across the deep, frigid Beaufort Sea before reaching an ice floe 426 miles offshore.

The marathon swim came at a cost: With little food likely available once she arrived, the bear lost 22% of her body weight and her year-old female cub, who set off on the journey but did not survive, the researchers said.

'Our activity data suggests that she swam constantly for nine days, without any rest. Which is pretty incredible,' said George M. Durner, a USGS zoologist and a lead author of the study, published last month in the journal Polar Biology."

Kim Murphy reports for the Los Angeles Times January 29, 2011. [2]