Berry bear
John Potter

Kodiak bears are the largest in the world. Big males can weigh 1,500 pounds and can measure up to 10 feet tall when they stand on their hind legs.

The bears are a separate subspecies, isolated from their ancestors on the island of Kodiak about 12,000 years ago.

One of the reasons they grow so big is that there is a lot of food for them on Kodiak Island. Every fall they like to eat spawning sockeye salmon, which enter rivers and creeks making them easy prey. They like to eat the fish's brains, flesh and eggs, which carry the most nutrition.

Thanks to warmer weather, though, fewer bears have been eating sockeye when they come to spawn in the summer. Scientists think it is because red elderberries, another food source the bears like, are ripening sooner. When given the choice between berries or fish, the bears have chosen berries the past two years. The bears seem to have a sweet tooth.

The elderberries used to ripen after the salmon had already run upstream. Now the bears have fruit weeks earlier.

The change in diet won't just affect bears, salmon and elderberry bushes. According to scientists it could also affect birds — like gulls — that depend on bears pulling salmon out of the stream. With more salmon spawning their numbers could grow. 

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"This overlap in their resources forces the bears to make a choice that could in the long run result in fewer bears and/or unexpected changes in ecosystem structure," said Jack Stanford, director emeritus at the University of Montana's Flathead Lake Biological Station and one of the researchers.

It's estimated there are about 3,500 bears on Kodiak Island, one of the densest populations of bears in the world. Because there are so many bears concentrated at times in very small areas, they have developed a language and way to express themselves to avoid fights.

— Brett French, Billings Gazette

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