JACKSON, Wyo. — The estimated number of grizzly bears in and around Yellowstone National Park has been revised downward by 6 percent from a year ago, but wildlife biologists say the drop isn’t cause for concern that the animals are in trouble.
“There’s no evidence of a major change in the long-term trend of the population, and the long-term trend is still flat to slightly increasing,” Frank van Manen, a wildlife biologist with the U.S. Geological Survey, said.
The number of grizzly bears in the Greater Yellowstone Ecosystem, which includes areas of Wyoming, Montana and Idaho, is estimated at 714 this year, down from 2014’s estimate of 757, according to information released at a meeting of wildlife biologists Wednesday.
The decline comes during debate whether federal protections for the grizzly bear should be lifted. Wildlife advocates say grizzly bear numbers are not sufficient enough to warrant lifting protections and subjecting the bears to possible hunting. But delisting advocates say grizzly bear populations have grown to the point where they are expanding beyond their current habitat and are coming more and more into conflict with humans.
Van Manen, a team leader with the Interagency Grizzly Bear Study Team, said the new grizzly bear population estimate is a single-year snapshot and not any indication that the population is in decline.
“It is within the range of variability, and we know there’s sampling bias involved,” he told the Jackson Hole News & Guide. “What we look at is that trend line over time, and if we look at that there’s no evidence of an actual decline.”
The model that federal bear managers use to gauge grizzly numbers is biased low, van Manen said.
“We are underestimating probably by about 40 percent, according to these calculations,” van Manen said.
Adjusting for the model’s underestimation, the grizzly population would have come in this year at around 1,000.
Van Manen presented data Wednesday to the Yellowstone Ecosystem Subcommittee that counted 52 grizzly bear deaths so far this year and 90 percent of those deaths have been caused by people.
But mortality levels for both sexes are still within the limits set by recovery plans, van Manen said.
Nearly 6 percent of female grizzlies have died this year, he said, which is below the 7.6 percent threshold that can lead to decline. Among boar grizzlies 11.4 percent have died, again below the acceptable mortality limit of 15 percent.
The grizzly bear has been a protected species under the Endangered Species Act for all but two years since 1975.
Officials with the U.S. Fish and Wildlife Service have said there are no firm plans to propose a rule that could lift protections for the Yellowstone ecosystem’s grizzly bears.