Scientists in the Arctic have recorded what is by far the longest swim a polar bear has ever been known to make. A female bear fitted with a radio collar swam continuously for almost 10 days through icy waters north of Alaska, covering 420 miles as she searched for ice floe hunting grounds. "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. It is truly an amazing feat," the lead researcher tells the BBC.
The epic swim, however, came at a huge cost to the bear: she lost more than a fifth of her body fat, and her yearling cub did not survive the journey. "It was simply more energetically costly for the yearling than the adult to make this long distance swim," the lead researcher says. The team says that as Arctic ice continues to decrease, polar bears will have little choice but to continue making such long swims, at equally high cost.