Polar Bear in 9 Day Continuous Swim

Scientists have tracked a female polar bear that swam 687 kilometers over nine days in the Beaufort Sea north of Alaska. But that wasn't all. She then walked and swam an additional 1,800 km, losing around 20% of her body weight during the journey to find a new ice floe.

The bear, which was first captured and collared in late August 2008, was tracked via a radio transmitter. The scientists, who work for the US Geological Survey, said that the "extraordinary long distance swimming ability of polar bears" may help the bears deal with the loss of Arctic sea ice.

"Our observation, however, indicates that long distance swimming in Arctic waters, and travel over deep water pack ice, may result in high energetic costs and compromise reproductive fitness."

The global population of polar bears is estimated between 20,000 and 25,000, according to the Natural Resources Defense Council. About one-fourth of polar bear populations is now classified as "declining" by the World Conservation Union's Polar Bear Specialist Group. The concern is that the early melting of Arctic ice because of temperature rise will reduce the amount of time the bears have to hunt. At the same time, less sea ice compels bears to swim longer distances than they are accustomed to, putting their lives at increased risk during storms.

"We are in awe that an animal that spends most of its time on the surface of sea ice could swim constantly for so long in water so cold," said research zoologist George M. Durner. "It is truly an amazing feat."

Their findings were published in the journal Polar Biology.