Polar bear swam nine days straight in search of ice
Thursday, January 27, 2011
New findings published recently that showed a female polar bear in the Beaufort Sea swam nearly 700 kilometres over nine straight days in search of ice paint a picture of a species on the brink, said one Canadian polar bear expert.
"The problem now is as the ice has changed, the ecosystem is becoming much less predictable for the bears and we're seeing more bears swimming greater distances and this doesn't bode well for the population," said Andrew Derocher, who works in the University of Alberta's department of biological sciences.
"The cost to the population is huge. We're potentially at least losing cubs and bears are going to end up in poorer condition . . . and they're less likely to survive or reproduce."
Derocher reviewed the paper for the U.S. Geological Survey before it was published in Polar Biology. The findings, based around GPS tracking of a bear in the Beaufort Sea in Alaska, were the centre of a BBC report this week.
The report said the bear was in the water for 232 consecutive hours in temperatures ranging from 2 C to 6 C.
Derocher is part of research groups tracking polar bears by similar means in western Hudson Bay off Manitoba, the Fox Basin in Nunavut and on the Canadian side of the Beaufort Sea.
"We've not seen any bears swim anywhere near those sorts of distances," he said, adding that most areas Canadian polar bears would frequent — with the exception of Hudson Bay — would not have 700 kilometres of open water to work with. He said the new findings are still representative of the future of the species around the pole.
He said large adult males might be able to top the performance of the bear cited in the study in Polar Biology, but estimates the nine consecutive days of swimming seen in the findings would be close to the maximum for a female bear.
"It's energetically expensive to do this," he said. "This bear lost over 20 per cent of its body mass . . . and she also apparently lost her offspring during this swim. We've always said that polar bears can swim long distances . . . but only certain bears can actually do it. Young animals, old animals and animals in poor condition are usually unable to accomplish anything like this."
Polar bears prefer to use sea ice as a link from one area to another, Derocher said, adding that under normal circumstances, polar bears would not be in the open water for any longer than 100 kilometres.
"It speaks to the desperation of an animal trying to live in a world that's changing so rapidly," he said. "The bears are trying to adapt to the changing conditions (in the Beaufort Sea), but every indication we have is that the bears aren't doing very well.
"The survival rate is going down, the number of cubs is down and the body conditions are down, so you put it together and it doesn't (look good) for the population."
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