Streams In Yellowstone Make A Comeback Thanks To Wolves And Cougars

Nov 19, 2018

The return of wolves and cougars to Yellowstone National Park is helping stream systems make a comeback. The new study published in the journal Ecohydrology suggests returning carnivores to a landscape can have a cascading effect across the ecosystem.

Bob Beschta is the lead author of the study and emeritus professor at Oregon State University.

"I spent my entire professional career working on streams and never once did I have conversation with ecologists about wolves and streams and their potential role," he said.

Without wolves or cougars in Yellowstone, Beschta said elk were able to browse for food wherever they wanted. That kind of free reign led to heavy degradation of plants that grow alongside streams, like willows, cottonwoods and aspen.

"Stream systems respond," said Beschta. "That is, without plants, they begin to widen, they begin to insize and they begin to change dramatically. And they erode."

But with elk and cougars impacting where elk can browse and for how long, those original streams are coming back. Beschta said the study could have implications outside of Yellowstone, especially in discussions around allowing large predators like wolves on other public lands.

This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Boise State Public Radio in Idaho, Yellowstone Public Radio in Montana, KUER in Salt Lake City and KRCC and KUNC in Colorado.

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