In a remarkable feat of endurance, a polar bear has been tracked swimming for nine days continuously in a desperate bid to reach new ice floes. The polar bear's 426-mile journey around the Beaufort Sea is equivalent to twice the length of the river Thames. Reuters

By Rob Hastings
Wednesday, 26 January 2011 In a remarkable feat of endurance, a polar bear has been tracked swimming for nine days continuously in a desperate bid to reach new ice floes, covering 426 miles in the process. The bears are excellent swimmers and are known to travel long distances in search of seals. But scientists working for the US Geological Survey, who logged the animal’s plight using a GPS tracking collar, said the animal’s exertions were exceptional – and further evidence of the extent to which the melting of the bears’ natural habitat due to global warming is threatening their very existence. The research, published in the Polar Biology journal, found that swims of such extreme distances “may result in high energetic costs and compromise reproductive fitness”. The journey did not end happily for the tracked animal. As well as shedding 22 per cent of her body weight, she also lost her young cub.

Melting sea ice forces polar bear to swim for nine days

By Ella Davies, BBC Earth News reporter
Tuesday, 25 January 2011 A polar bear swam continuously for over nine days, covering 687km (426 miles), a new study has revealed. Scientists studying bears around the Beaufort sea, north of Alaska, claim this endurance feat could be a result of climate change. Polar bears are known to swim between land and sea ice floes to hunt seals. But the researchers say that increased sea ice melts push polar bears to swim greater distances, risking their own health and future generations. In their findings, published in Polar Biology, researchers from the US Geological Survey reveal the first evidence of long distance swimming by polar bears (Ursus maritimus). “This bear swam continuously for 232 hours and 687 km and through waters that were 2-6 degrees C,” says research zoologist George M. Durner. “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.” Although bears have been observed in open water in the past, this is the first time one’s entire journey has been followed.  … Mr Durner tells the BBC that conditions in the Beaufort sea have become increasingly difficult for polar bears. “In prior decades, before 1995, low-concentration sea ice persisted during summers over the continental shelf in the Beaufort Sea.” “This means that the distances, and costs to bears, to swim between isolated ice floes or between sea ice and land was relatively small.” “The extensive summer melt that appears to be typical now in the Beaufort Sea has likely increased the cost of swimming by polar bears.” …

Polar bear’s epic nine day swim in search of sea ice