Polar bear swam 9 days in search of sea ice, study says

Allison Cross - 

A mother polar bear swam for nine days straight to reach sea ice, covering nearly 700 kilometres and losing her cub in the process, according a new study on the movement of female polar bears.

The study, which links shrinking sea ice as a possible threat to polar bear cubs, also noted the bear lost 22 per cent of her body weight after swimming in the Beaufort Sea.

“It’s pretty remarkable. That’s the longest that’s ever been recorded for bear swimming non-stop,” said Anthony Pagano, the study’s lead author and a U.S. Geological Survey wildlife biologist. “Historically, there just wasn’t this extensive amount of open water that bears would be forced to swim (in).”

Initial results from the ongoing study, which used data from GPS collars on 68 bears, were presented last week at the International Bear Association Conference in Ottawa.

Scientists tracked the movements of the bears between 2004 and 2009 in the Beaufort and Chukchi Seas, and found their journeys in the water were an average of 150 kilometres long.

They also saw an increase in the number of swims over the course of the study.

“About a quarter of our . . . bears had these (greater than 50 km) swims in 2004,” Pagano said. “And in 2009, just over 60 per cent had swims.”

The long swims are likely very strenuous on the bears, said Pagano, and often fatal for their cubs.

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