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Researcher Criticizes Yellowstone Grizzly Population Model

Ahead of a potential Yellowstone grizzlies delisting move, at least one researcher has called into question the model used to estimate their population.

Specifically, the researchers questioned whether Chao2 (the model used by the U.S. Fish and Wildlife Service to predict the bear’s population in the Greater Yellowstone Ecosystem) accurately accounted for the impact of hunting.

According to a press release, Professor Len Broberg of the University of Montana, using a modeler called RAMAS, predicted hunting would lead to sharper declines in the Yellowstone grizzly population than the estimate reached under Chao2. The model echoes concerns raised by Yellowstone Superintendent Dan Wenk, who feared delisting the bear would cause numbers to decline even in the Park, which could have a deleterious economic and ecological effect. From the press release:

“Even if things stay basically as they have been for the past decade, my model indicates that the rate of harvest they’re projecting may cause some serious problems for grizzly bear population size,” Broberg said.

The committee’s model underestimates the number of males that would be killed by hunters, Broberg said. But Montana Fish, Wildlife and Parks dispute this claim.

Ken McDonald, wildlife division administrator at Montana Fish, Wildlife and Parks, said the agency will continue to rely on the Chao2 system to monitor the number of bears. He argued that if hunting is approved, it will be done in a responsible manner with the three states working together.

“There’s this misperception that hunting is going to be wide open, unlimited,” McDonald said. “All the states have put together – as a requirement of delisting – what hunting would look like in their state.”

The agency does not plan to track bear numbers on its own.

Broberg added the population is currently “sizeable,” and could probably sustain a slight rate of hunting. However, Broberg added, “I’m concerned that the rate that’s being proposed right now does not necessarily match up well with that objective.”

According to the U.S. Geological Survey, at least 55 grizzly bears were killed in the Greater Yellowstone Ecosystem—an unusually high number.

The Interagency Grizzly Bear Committee, which approved a conservation strategy earlier this year, will meet in Missoula, Montana Tuesday.

About Sean Reichard

Sean Reichard is the editor of Yellowstone Insider and author of Yellowstone Insider For Families 2017.

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