Alaska: Giant role for bears in spreading berry patches

When two American scientists were wandering through the Alaskan southeast forest, they were overwhelmed by the number of berries there. Salmon-berries, high bush cranberries, soapberries, blueberries, devil’s club berries and more. And not just here and there, but all throughout the forest.

Laurie Harrer, biology instructor at Central Oregon Community College and Oregon State University: “There are just a ton of berry-producing plants in Southeast Alaska. In particular, Devil’s Club is everywhere. If it is that prolific, and all over the place, it must have a very successful method of dispersing its seeds around.”

Together with Taal Levi, assistant professor of wildlife at Oregon State, Harrer set up a study. Over two summers, they identified more than 400 clusters of berries in a stretch of forest about 30 miles. They indexed the plants and trained motion-triggered cameras on the plants, to see what was eating them.

“A bird would fly in and maybe peck and eat anywhere between two and five berries at a time,” Harrer said. “But when a bear would visit these clusters of berries, they would just demolish the entire area. After we crunched the numbers, we realized how huge of an effect bears were having. ”

As reported in an article by, bears weren’t just eating more berries; they were eating magnitudes more berries. A single bear would eat over 100,000 berries an hour. This makes them into cargo carriers, taking seeds far away from the original berry patch.

So bears are really helping plants to reproduce. Dispersed berries have a better chance than those that just dropped from the bush. And when bears finally release the seeds, they even leave something to help them grow: berry seeds land on the ground with their own fertilizer already accompanying them.

Based on their research, Levi and Harrer believe bears are the most important seed dispersers in the region for berries. “Because there are so many bears, it’s understandable why you have so many more berries in Alaska."

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