Increased polar bear cannibalism observed due to sea-ice habitat loss

“An adult polar bear is seen dragging the body of a cub that it has just killed across the Arctic sea ice.

Polar bears normally hunt seals but if these are not available, the big predators will seek out other sources of food - even their own kind.

The picture was taken by environmental photojournalist Jenny Ross in Olgastretet, a stretch of water in the Svalbard archipelago.

“This type of intraspecific predation has always occurred to some extent,” she told BBC News.

“However, there are increasing numbers of observations of it occurring, particularly on land where polar bears are trapped ashore, completely food-deprived for extended periods of time due to the loss of sea ice as a result of climate change.”

The journalist was relating the story behind her pictures here at the 2011 American Geophysical Union (AGU) Fall Meeting, the largest annual gathering of Earth scientists.

A paper describing the kill event in July 2010 has just been published in the journal Arctic. It is co-authored with Dr Ian Stirling, a polar bear biologist from Environment Canada.

Ross had approached the adult in a boat. She could see through her telephoto lens that the animal had a meal, but it was only when she got up close that she realised it was a juvenile bear.

The kill method used by the adult was exactly the same as polar bears use on seals - sharp bites to the head.

“As soon as the adult male became aware that a boat was approaching him, he basically stood to attention - he straddled the young bear’s body, asserting control over it and conveying ‘this is my food’,” the journalist recalled.

“He then picked up the bear in his jaws and, just using the power of his jaws and his neck, transported it from one floe to another. And eventually, when he was a considerable distance away, he stopped and fed on the carcass.”“

Sources: BBC, Arctic Institute of North America

Update: More pics (graphic)