Polar bears, a species in steady decline throughout the Arctic, are most vulnerable in early spring as they leave their lairs and move to the north. The WWF's Polar Bear Patrol launched a campaign in April on monitoring the bears in coastal areas.
A coordinator of the project, Vladilen Kavry, said the researchers have so far found only three abandoned lairs and met only one polar bear with two cubs. He said this was a clear sign that the bear population has been significantly reduced.
"In the 1990s large numbers of bears were shot in Chukotka when most villages were on the brink of starvation. Now the bear population faces a negative influence from climate change," Kavry said.
The coordinator said illegal trade in the hides of polar bears was on the rise in Russia. The polar bear population in Chukotka is currently estimated at between 3,000 and 5,000. Some 200 of the bears are killed annually, according to World Wildlife Fund statistics.
According to the U.S. Geological Survey, two thirds of the world's 25,000 polar bears could die by 2050, as the ice they use to hunt seals melts due to global warming.
The hunting of polar bears was internationally banned in 1957.