“The islands of Wrangel and Herald are not called the ‘maternity home of polar bears’ by accident. This is where the majority of pregnant females of the Chukotka-Alaskan polar bear population lie in dens every year,” says Mikhail Stishov, WWF-Russia project coordinator for Arctic biodiversity conservation. “Understanding the importance of this territory, we readily supported a new research project. WWF provided the reserve with four professional quadcopters, two with thermal imagers. And at the end of last year, with our support, nature reserve staff took drone control courses.”
Polar bears are usually counted between March and April, when females leave the birth dens and take their cubs to sea ice to teach them survival and seal hunting skills. Traditional polar bear counting methodology involves groups of specialists riding snowmobiles around the areas with the highest concentration of dens. On each trip, they inspect every slope, valley and any other areas where a layer of snow allows the bears to dig out temporary housing. But finding a den is not an easy task. Most dens are in high, hard to reach crevices, with entrances only one meter in diameter. These openings can be hard to spot when the blinding sunlight is reflecting off the snow.
A drone with a thermal camera can help to overcome these difficulties. The temperature inside the den is much higher than outside, and when flying around the territory, a thermal halo illuminating these habitats can be seen on the drone control panel. The expert can then record and examine these findings in detail with a high-resolution camera.