Dr. Tom Smith of BYU and BJ Kirschhoffer of PBI talk about studying the maternal dens of the polar bears on Alaska's north slope.

© Polar Bears International

2/15/2016 5:53:57 PM

Maternal Den Study 2016: Finding Polar Bears in the Great, White North

Fieldwork in the Arctic is especially challenging in winter, with bitterly cold temperatures and rapid weather shifts. But it also yields important information on polar bears, which is why scientists venture into the vast whiteness year after year.

At the end of February, PBI's Geoff York, senior director of conservation, Dr. Tom Smith of Brigham Young University, who serves on our Scientific Advisory Council, and Wes Larson, BYU graduate student, will fly to Alaska to deploy video camera monitoring systems at polar bear maternal den sites.

Locating a polar bear den is not an easy task in the flat light and totally white landscape of the North Slope. The wind whips, the sky is almost the same color as the ground, and it's virtually impossible to see any definition in the landscape.

In past years, researchers have been led to polar bears' dens by following pregnant females wearing radio or satellite collars, or more recently with Forward-Looking InfraRed (FLIR) technology, which can detect heat under the snow. The field team then place cameras 100 meters from the dens to monitor the mother and cub exiting and their behavior while in the area.

Six weeks after placing the cameras, they pick them up and analyze the footage—hours of snow and blowing snow—and, if they are lucky, moments of behavior rarely seen by people.

This year the team is faced with a new challenge: no known dens to monitor.  They will guide their efforts with information provided by the U.S. Fish and Wildlife Service FLIR surveys, the joint PBI/BYU/Michigan Tech Research Institute SAR den survey, and the historical den data record.

"We will be visiting high-probability areas where we have had success in the past," York said. "We have three to four places in mind where we will have a reasonable chance of observing polar bear denning activity."

The researchers will also set the cameras further back than in past years to get a wider shot, and thus a better chance of filming the bears as they leave the den.

The maternal den studies provide a baseline of polar bear behavior in northern Alaska. The 14-year-old study addresses the following questions:

  • When do polar bears typically emerge from their dens with cubs?
  • How long do families hang around at the den site before heading to the sea ice to hunt seals?
  • What do they do?
  • How sensitive are denning polar bears to human disturbance?

Smith said they've found that "individual bears can be pretty resilient to human activities, but it is sometimes hard to tell what causes an early den departure."

 As their sea ice habitat forms later in the year and melts earlier, due to anthropogenic climate change, more polar bears may be denning on land than on sea ice, a notable shift from behavior in the past.

This research gives us a broader picture of denning behavior—increasingly important information as human activity increases and the sea ice shrinks.

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