28.01.2011 | 13:12
A polar bear swam continuously for over nine days, covering 426 miles, animal researchers were astonished to discover, Daily Mail reported.
And the scientists studying bears around the Beaufort Sea, north of Alaska and Canada, 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 the survival of the species.
In their findings, published in the journal Polar Biology, researchers from the US Geological Survey reveal the first evidence of long distance swimming by polar bears.
One of the bears they fitted with a tracking collar made an epic journey in search of food between an initial capture in late August and a recapture in late October 2008.
'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.'
The study found that, in addition, the bear then intermittently swam and walked on the sea ice surface another 1200 miles.
Although bears have been observed in open water, this is the first time one's entire journey has been followed. By fitting a GPS collar to a female bear, researchers were able to accurately plot its movements for two months as it sought out hunting grounds.
Unfortunately for the bear, the feat came at a high cost. Not only did the polar bear lose body mass, she also lost her yearling cub along the way.
The baby bear simply could not survive the swim across the increasingly perilous Beaufort Sea in Alaska.
Polar bears swim from ice floe to ice floe in search of their main prey, ringed seals, but the warming global temperature has made the journey a bit harder.
'The extensive summer melt that appears to be typical now in the Beaufort Sea has likely increased the cost of swimming by polar bears.'
The bears hunt their prey on frozen sea ice: a habitat that changes according to temperature.
'This dependency on sea ice potentially makes polar bears one of the most at-risk large mammals to climate change,' says Mr Durner.
The International Union for Conservation of Nature identifies polar bears as a vulnerable species, citing global climate change as a 'substantial threat' to their habitat.
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