Polar bears face swimming to land or ‘ecological trap’ as sea ice diminishes

Outdoor Alaska: Dimishing sea ice prompts polar bear behavior changes
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ANCHORAGE, Alaska (KTUU) – Changing sea ice conditions are forcing polar bears to adapt. New research shows that a growing percentage of polar bears are coming to land and becoming dependent on human provisions for food, while those that stay on the dwindling sea ice to continue natural polar bear behavior may be floating on an ecological trap.

The USGS researchers used GPS collars with a camera, accelerometor and other scientific tools to track and analyze the bears’ behaviors.

Researchers with the USGS Alaska Science Center have noticed the behavioral changes in polar bears on the Southern Beaufort Sea over the last 15 years and more recently a team began studies to determine which behavior was better for the bears. The researchers used GPS collars with video cameras and an accelerometer to track the bears, calculate how much energy they used, and compare the energy requirements of coming to land during summer months versus staying on the sea ice.

“Going into it we thought it’s surely going to be more energetically expensive to come to shore, because often times bears are staying on the sea ice until the last possible minute before they come to shore,” Todd Atwood, a research wildlife biologists with USGS said. “In some cases bears are swimming 400, 500 kilometers to get to land. Swimming is a lot more energetically expensive than walking. So we expected them burn through a lot more energy to get to land, and that’s what we found.”

By pairing the GPS camera collar with a tri-axial accelerometer, the researchers were able to estimate how much energy bears used for different behaviors by calculating overall dynamic body acceleration.

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