One of Alaska's own polar bear experts is making headlines this week with a new revelation about the toll climate change is taking on polar bears as a result of melting sea ice. A group of scientists recently documented a mother bear's "epic nine-day swim in search of ice" in the waters of the Beaufort Sea.

"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," George M. Durner told BBC News, which reported the findings Tuesday. Durner is a research zoologist with the U.S. Geological Survey in Anchorage at the Alaska Science Center.

With data collected over a two-month period in 2008, Durner and his colleagues chronicled the bear's eastward journey along the Alaska coast, during which she made that incredible nine-day, 426-mile swim from land to floating pack ice over the sea's deep waters. Along the way, she lost her yearling cub and 22 percent of her body weight: more than 100 pounds.

"Our observation confirms that yes, indeed, polar bears are capable of, they have the ability to undergo these extraordinary behaviors such as long distance swimming. No one else has been able to provide data like this before," Durner said in an interview from his Anchorage office Tuesday.

The comprehensive data comes from a unique mix of hi-tech gadgets that were affixed to the bear in August 2008, each equipped with computer chips that recorded and preserved the data that scientists were able to download two months later, when the bear was again captured.

Through satellite tracking, motion detectors and thermometers they kept tabs on her every hour of every day. They not only knew where she was but also whether she was walking or swimming, resting or active, and how warm or cold it was outside or in the water and, with a sensor buried in the fat beneath her skin, they recorded her own body temperature -- a blend of gadgets designed to assist not only the USGS ongoing studies, but also a University of Wyoming study looking specifically at the physiology of polar bear on land and sea ice during summer in the Beaufort Sea. For scientists, having all of the technology on a single animal was a rare expedition that, as best as it could, let them travel alongside the mother bear via data diary.

"What makes her particularly unique is the wealth of data that we have available from this animal to be able to tell a story about what she experienced," Durner said.
What was her life like in the two months scientists eavesdropped on her? She started as a healthy, 500-pound bear that was lactating and caring for a yearling cub. At some point she left Alaska's coast and went for a swim in search of sea ice, the floating surface bears use to travel over hunting grounds.

Along the way, during the swimming journey that went on far longer than scientists have to-date recorded, she lost her cub. Durner suspects it died from exhaustion during the long, 426-mile swim from land to pack ice, but there's no way to know for sure. The floating ice pack was farther off shore than usual -- a trend attributed to melting sea ice and climate change. And it was over deep waters which aren't as food-rich as the shallower continental shelf, over which summer pack ice in years past has been found.

By the time scientists caught up with the polar bear again in October 2008, she had traveled hundreds of miles eastward toward Canada. Her cub was gone, she had stopped lactating and she had lost a lot a weight.

In the past, polar bears haven't had to swim as far to reach the ice, Durner said, adding that the mother bear probably had no idea what she was getting herself into.