ANCHORAGE, Alaska – Polar bears in the southern Beaufort Sea may be turning to cannibalism because longer seasons without ice keep them from getting to their natural food, a new study by American and Canadian scientists has found.
The study reviewed three examples of polar bears preying on each other from January to April 2004 north of Alaska and western Canada, including the first-ever reported killing of a female in a den shortly after it gave birth.
Polar bears feed primarily on ringed seals and use sea ice for feeding, mating and giving birth.
Polar bears kill each other for population regulation, dominance, and reproductive advantage, the study said. Killing for food seems to be less common, said the study’s principal author, Steven Amstrup of the U.S. Geological Survey Alaska Science Center.
“During 24 years of research on polar bears in the southern Beaufort Sea region of northern Alaska and 34 years in northwestern Canada, we have not seen other incidents of polar bears stalking, killing, and eating other polar bears,” the scientists said.
Environmentalists contend shrinking polar ice due to global warming may lead to the disappearance of polar bears before the end of the century.
The Center for Biological Diversity of Joshua Tree, Calif., in February 2005 petitioned the federal government to list polar bears as threatened under the federal Endangered Species Act.
Cannibalism demonstrates the effect on bears, said Kassie Siegal, lead author of the petition.
“It’s very important new information,” she said. “It shows in a really graphic way how severe the problem of global warming is for polar bears.”