Global Warming Altering Polar Bear's Food Chain

Global warming is altering the food chain of the arctic which is reeling under thinning ice cover.

Researchers at Norwegian Polar Institute described polar bears preying on white-beaked dolphins during last spring. The dolphins are known to head up north during summers when the ice is thinner but not in spring or winter. The thinning of ice with more than normal surface water could have forced dolphins to venture north, where the bears may have ambushed them when the dolphins surface for air, The Guardian reports.

"An increase of white-beaked dolphins in areas where the sea ice shifts northward may, given the significant size of these animals, offer a new prey or carrion food source to bears in an environment where access to ringed seals and bearded seals may decline in future years," researchers wrote in Polar Research journal. Polar bears usually feed on seals. This is the first recorded instance of polar bears preying on dolphins.

The paper describes dolphins getting trapped under the sudden ice cover, rendering them vulnerable to polar bears. Researches also wrote about an unusual caching behavior of the bears. They witnessed a male polar bear shoving the remains of a dolphin under ice for later consumption. Researchers termed such behavior unusually of polar bears.