Grizzly counts under review
In effort to show species is healthy, managers seek to shrink area where bear deaths are counted.
By Cory Hatch, Jackson Hole, Wyo.
April 25, 2012
Grizzly managers have proposed new ways to count bears and bear deaths in the Greater Yellowstone Ecosystem that could make it easier to end federal protection of the species.
In the absence of accurate grizzly bear demographics, the changes are expected to increase the estimated number of bears in the population while decreasing the estimated number of mortalities, experts say. The idea surfaced at a meeting of Yellowstone area grizzly mangers in Teton Village last week.
The current method for estimating the size of the grizzly population — by counting females with cubs of the year from the air and ground and by trapping — is inaccurate, USGS biologist Mark Haroldson said at the gathering last week. The mathematical formula estimates the population at between 533 and 652 animals, but Haroldson said it is likely larger.
While the math worked well when the population was small, the formula is obsolete now that the numbers have grown, he said.
“We have a conservative population estimate,” he told the Interagency Grizzly Bear Committee’s Yellowstone group. “We know [the method] is biased low, and it becomes more biased at higher population numbers.”
With the new method, biologists would count females with cubs using aircraft only. They would not seek grizzlies from the air with the aid of radio collars.
Instead, they would fly specified patterns and count the number of both collared and uncollared bears.
Since wildlife managers would know how many bears they have collared, the ratio of collared to uncollared bears spotted on flights would enable them to calculate the population.
Grizzly bear managers have also proposed shrinking the area where they count grizzly bear deaths.
The number of bear deaths is important because the data is used to judge the health of the population, including whether it is growing, staying steady or declining. When a certain threshold is passed, the Endangered Species Act requires managers to do a comprehensive review of the species. That review includes identifying threats to bear survival.
For the last two years, the number of bear deaths passed the mortality limits, triggering such a review.
The area where grizzly deaths are now counted encompasses about 38,600 square miles and, in Wyoming, includes the Wind River Range, most of the Wind River Indian Reservation, the Wyoming Range and agricultural land in Sublette County.
The proposed boundary would reduce the area where bear deaths are counted roughly by half. The proposed area encompasses about 19,305 square miles managers say they consider biologically suitable habitat for bears.
The zone includes most of the Wind River Range and Montana’s Gravelly Range, but otherwise would keep to currently occupied grizzly bear habitat around Yellowstone National Park. Shrinking the zone in which grizzly deaths are counted means bears that die outside the boundary won’t be counted as losses to the population.
The land that makes up the difference between the current and proposed areas is mostly unsuitable bear habitat, Haroldson said.
“Right now we’re being penalized for success,” he said. “We have bears that are leaving these boundaries, getting into conflicts and being counted against our mortality limits.”
Reducing the count of bear deaths also would improve the population outlook and help managers make a case for less federal oversight.
The good news for conservation groups is that the federal government is recognizing the Wind River Range as biologically suitable grizzly bear habitat, Natural Resources Defense Council senior wildlife advocate Louisa Willcox said after the meeting.
“It’s a step in the right direction in recognizing that bears have a legitimate place in the southern Wind Rivers and the Gravelly Range,” Willcox said. “Previous plans had not really affirmed that.”
However, there is still a discrepancy between where grizzly managers are counting bears and where they are protecting habitat, Willcox said. Currently, habitat is only protected in the Primary Conservation Area, which includes Yellowstone National Park and the federal land, mostly U.S. Forest Service land, close to it.
“They’re counting in this larger area and they’re establishing mortality limits using those counts, but they’re not protecting habitat in that larger area,” Willcox said.
There is some land outside of the proposed count-area boundary that is suitable habitat for bears, Willcox said.
Not everyone at last week’s meeting agreed with the proposed new boundary. Idaho Fish and Game regional supervisor Steve Schmidt suggested it could make it difficult to kill problem bears.
“I think we need to think carefully about what it might mean in the future ... to create our biologically suitable area as our line in the sand,” he said. “Will that limit our management options in the future if we have bears in the biologically suitable area? We know bears in the biologically suitable area are going to get into trouble.”
Hoback outfitter Sam Coutts said the federal government has done a poor job keeping track of grizzlies in the ecosystem.
“We don’t have any idea how many bears we have out here,” he said.
“You’ve got to get a crane to set up a bird feeder on the outside of your house,” he said, pointing to county regulations that require keeping clean neighborhoods. “All these big predators that we have are all down over the top of us.”
Federal researchers should take a lesson from the military and use thermal imagery to count bears, Coutts said.
“You could fly that with thermal and in two days count the number of bears that are out there,” he said. “This is a waste of the taxpayers’ money.”
Regardless of how bears are counted, the ecosystem’s population growth appears to have backed off the 9 percent annual growth rate seen in the past, Haroldson said.
“We’ve seen a decline in cub survivorship,” Haroldson said. “We’ve seen a decline in yearling survivorship.
“Data ... suggest that subadult survivorship has declined also,” he said. “We are catching less subadults in the population than we were previously.
“We’ve got multiple analyses that point to the same conclusion: The rate of population growth has declined,” Haroldson said.
The question is whether grizzly bears have used up all the suitable habitat, or whether the decline is due to another factor: a reduction in whitebark pine seeds, an important grizzly food.
In November, a three-judge panel in the 9th Circuit Court of Appeals agreed the federal government should not be allowed to stop protecting the grizzly. As a result, the bear remains a federally protected threatened species.
Judges concluded the U.S. Fish and Wildlife Service failed to show that whitebark pine declines were not a threat to Yellowstone grizzlies. By showing that the population is robust, the new accounting methods could help the agency convince the courts that a lack of whitebark pine seeds wouldn’t mean the demise of the grizzly population
Grizzly bears can readily find other foods, Haroldson said.
“In poor whitebark pine years, they’re eating truffles,” he said. “They’re doing a lot of mushrooming.
“There’s no sign of a collapse in the bear population,” Haroldson said. “This whitebark pine issue will play out ... and so far we’re doing OK.”
Willcox said researchers on the study team need to do more to find out how grizzly bears are getting those calories.
“There is not one piece of peer-reviewed science that shows that truffles are a sufficient substitute for whitebark pine,” she said.
“Whitebark pine had a unique role in this ecosystem in its direct relationship with larger litters and lowering mortality rates because of where it grows. Do these alternative foods serve the same function, and if they don’t, what are the consequences to the population?”
Federal wildlife managers say they’ll put the proposals out for public comment before they are implemented.