September 22, 2009

Northern brown bears feed on whitefish

Canadian scientists say they have discovered brown grizzly bears are feeding on migrating broad whitefish in a Northwest Territories stream.

Scientists from the University of Alberta say the discovery in the Mackenzie Delta region of the Northwest Territories has researchers advising increased care in petroleum extraction and infrastructure development within the area.

Oliver Barker and Andrew Derocher, who led the study, said they observed at least one brown bear engaged in the unusual activity of caching whitefish at Pete's Creek, a small Mackenzie River tributary located between Inuvik and Tuktoyaktuk.

The study marks the first scientific reporting of brown bears feeding on whitefish and supports what is recorded from local traditional knowledge.

Brown bears in the Mackenzie Delta face several challenges. Not only are food sources scarce, the bears are often active for just five months of the year, the scientists said. That creates extreme pressure for them to find adequate nutrition.

These bears are real opportunists. They'll take advantage of different food sources, Barker said. This means some will turn to whitefish which are easily available in large numbers when they migrate in the fall. And although bears are omnivores and can exist on mostly vegetarian diets, fish are a better food source because they are rich in protein and fat.

The discovery is reported in the September issue of the journal Arctic.