Scientists are not drawing any conclusions about a relationship between global warming and their newly released findings that female polar bears and their cubs are routinely completing 100-mile swims through Arctic waters. U.S. Geological Survey biologists attached collars with GPS technology to 52 bears over a five-year span in the Beaufort Sea off Alaska, reports Dot Earth blogger Andrew Revkin in The New York Times. They recorded 50 swims averaging 96 miles. One bear swam over 200 miles.
The study was too limited to clarify whether the warming Arctic climate and related summer expansion of open water in the Arctic Ocean is necessitating more long swims - or whether that is reducing the bear's survival rate or reproductive success. The paper notes that cubs accompanied mothers on a number of the marathon swims. In a phone interview this morning, the lead author, Anthony Pagano, noted that the bear population in the study region, the southern Beaufort Sea, appears to be stable at about 1,500 animals.
The scientists say lack of swimming data on polar bears prior to this study makes it impossible to determine whether they are swimming longer as Arctic ice recedes in the face of global warming. In 2011, USGS researchers reported a 426-mile apparently nonstop swim by a female polar bear.