Global Warming

Alaska's Grizzly Bears Drop Salmon for Berries as Climate Changes

When Kodiak Island's elderberries started ripening earlier, its icon bears changed their diet. It's another ecological shift amid climate change, scientists say.

Each summer, the shallow freshwater streams of Kodiak Island, Alaska, are so thick with sockeye salmon, you literally cannot cross the waterways without stepping on the brightly colored fish. With the salmon come brown bears, often dozens of grizzlies per stream, hauling the fish onto nearby banks for an easy meal.

During an unusually warm summer in 2014, however, no bears could be found. At the peak of the annual salmon run, as the fish made their way upstream to spawn, the roughly 1,000-pound bears were busy feasting on berries instead, according to a study published today in the Proceedings of the National Academy of Sciences. A similar phenomenon is believed to have also occurred in 2016, after the study period ended, but the bears were not closely monitored to confirm their feeding behavior.

Biologists who study Alaska's iconic omnivores say changes in seasonal phenomenon caused by a warming planet were behind the bears' unusual behavior, which could affect the entire ecosystem.

Different species are responding to climate change in different ways, "so what you have is a scrambling of the schedule," said William Deacy, a biologist at Oregon State University in Corvallis and lead author of the study.

The island's brown bears typically feed first on salmon, followed by elderberries later in the season. An earlier-than-usual ripening of red elderberries, however, forced the bears to make a choice.