Jenny E. Ross

ScienceShot: Polar Bear Cannibalism on the Sea Ice

Carolyn is a staff writer for Science and is the editor of the In Brief section.

On 21 July 2010, a photographer observed a polar bear guarding its kill out on the sea ice in Svalbard, Norway. Not an unusual event—except that the prey it held in its mouth was another polar bear, a yearling cub. Even that was not unheard of: Inuit hunters in Greenland and Canada have long known that polar bears—usually adult males—might kill younger polar bears for food. But such events have only been reported on land, not on sea ice, and no one had photographed it before. Since then, says the photographer, Jenny Ross, there have been two other documented sightings of adult male polar bears on sea ice feeding on their younger bear kills, one in September 2009 and one in July 2010. Given the dwindling sea ice and the scarcity of seals nearby at that time of year, young polar bears may simply be the most available prey, Ross and Arctic biologist Ian Stirling of Environment Canada in Edmonton note in the December issue of Arctic. But, they add, it might also be a sign of things to come: A warming climate and less and less sea ice will send seals northward even earlier in the summer, and the frequency of intraspecies predation could increase.

Correction: This item originally misstated the date of the event in the photograph and the age of the younger polar bear.

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