Yellowstone griz population rises slightly in a year
By Mike Koshmrl, Jackson Hole, Wyoming
Date: November 19, 2012
The estimated population of grizzly bears in the Greater Yellowstone Ecosystem has increased slightly in the past year, from 593 to 608.
Biologists divulged the new numbers during a subcommittee meeting of the Interagency Grizzly Bear Committee in Bozeman last week, said Mark Bruscino, the Wyoming Game and Fish Department’s large carnivore section supervisor.
The ecosystem population estimate is conservative, Bruscino emphasized.
“I would call it a minimum estimate,” he said in a phone interview. “The [counting method] we have right now is biased low, and we know that. It’s statistically very easy to understand why it’s biased low.”
Bruscino said the current counting method has a problem.
“As bear density increases, your ability to discern different females with cubs decreases,” Bruscino said. “For example, if there’s five females with cubs in the Lamar Valley, using the current technique, you may only be able to use two or two of those because we don’t use anything that may be a duplicate sighting.”
The Interagency Grizzly Bear Study Team is switching to a new counting method that will better represent the population, Bruscino said.
“The current technique is based on a minimum known females with cubs of the year, and the new technique will be an estimate of total females with cubs of the year,” Bruscino said.
The estimate provided by the grizzly committee this year uses the old counting method, and compares the 2011 and 2012 counts as “apples to apples,” Bruscino said.
Biologists and statisticians are still working out the kinks in the new method, but they could have it finalized by the time the Interagency Grizzly Bear Committee holds its semi-annual meeting in Jackson Hole in the spring, Bruscino said.
Through Friday, there were 50 “known or probable” grizzly bear deaths in the Greater Yellowstone Ecosystem, Northern Rocky Mountain Science Center data show. The study team posits two grizzly deaths for every one that is detected, but the multiplier does not apply to cub deaths. Bruscino called it a “high” but “sustainable” year for grizzly mortality.
Grizzly bears are protected under the Endangered Species Act, but there’s been a push from Gov. Matt Mead, other western states and the Department of the Interior to delist the bruin. That would open the door to grizzly bear hunting in Wyoming.
“Hunting is an option in our management plan,” Bruscino said.