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Grizzly bears making homes far from Yellowstone
Conservationists say core habitat area needs to be larger.
By Cory Hatch, Jackson Hole, Wyo.
Date: July 6, 2011
The Greater Yellowstone’s grizzly population is now large enough that some bears are expanding to locations in Wyoming where they haven’t been seen for decades — places where they could face trouble, bear managers say.
These grizzly sightings have occurred far from what biologists consider suitable habitat, places like the Gooseberry drainage southeast of Meeteetse, desert environments in the Bighorn Basin and the Big Sandy area of the southern Wind River Range, said Mark Bruscino, bear management program supervisor for the Wyoming Game and Fish Department.
“This year we’ve had several bears documented in places where we didn’t expect bears to show up,” he said. The Gooseberry drainage bear is “the farthest east we’ve known a grizzly bear to be in the last 50 years.
“In the Bighorn Basin, even though historically bears probably used these riparian corridors out in this desert environment, they haven’t been seen there in many years,” Bruscino said.
Other odd locations for grizzlies include Heart Mountain north of Cody and areas south of Lander.
The grizzly population has grown at about 4 percent per year since the species was first protected in the 1970s.
Biologists conservatively estimate the population at more than 600 grizzlies, up from an estimated 224 in 1975.
Some wildlife managers say there could be as many as 1,000 grizzlies in the ecosystem.
As the population has grown, so has its range, said Chuck Schwartz, the Interagency Grizzly Bear Study Team leader. In the 1970s, the estimated range encompassed nearly 6,000 square miles.
By the 1980s, that territory had grown to 6,500 square miles, then to nearly 8,900 square mile in the 1990s, and to 13,000 square mile through about 2000.
The most recent estimate has grizzly bears occupying about 22,000 square miles.
Schwartz cautioned that the formula used to calculate those numbers has evolved over the years, but he said it still gives a good picture of how the bear’s range has expanded.
“Back when the bear was listed, in the ’70s, bears were left in Yellowstone National Park and some of the surrounding wilderness,” he said. “Since about the late ’90s, we are beginning to see bears show up in places where people never thought about grizzly bears.”
Outside of Wyoming, bears have ranged as far as Dillon, Mont. On July 1, The Seattle Times reported a bear in the North Cascades of Washington.
The estimated 22,000 square miles currently occupied by grizzly bears is well beyond the U.S. Fish and Wildlife Service primary conservation area, a 9,200-square-mile area encompassing Yellowstone National Park and some of the surrounding forest that is a federal recovery zone for the species.
The goal for the primary conservation area is to maintain suitable habitat for grizzlies.
“This means that the number of developed sites, livestock allotments and total amounts of secure habitat will be maintained at or improve upon conditions present in 1998,” according the U.S. Fish and Wildlife Service website.
“In addition,” the website continued, “several other habitat parameters will be monitored, which include such things as distribution and abundance of major natural foods (army cutworm moths, winter-killed ungulate carcasses, cutthroat trout, and whitebark pine seeds).”
Conservation groups say bear managers need to focus on identifying more suitable habitat for the species, not limiting the animal’s movements. That includes expanding the grizzly bear primary conservation area.
“One of our goals has been to get the primary conservation area more closely linked to suitable habitat,” said Mark Pearson, conservation program director for the Greater Yellowstone Coalition.
Providing wildlife corridors between suitable locations is also imperative, Pearson said.
“It seems like bears are going to move into the Wyoming Range and the Wind Rivers,” he said. “We want them to be able to move into the central range in Idaho and northwest.”
Conservation groups also say the region’s grizzlies need connectivity with other populations of bears to maintain genetic diversity. Bear managers say that diversity could be attained, if necessary, by capturing bears from other populations and releasing them in the Greater Yellowstone Ecosystem to breed.
“Ultimately, we need a connection between Yellowstone and Glacier bears,” Pearson said. “Hopefully, that can happen naturally without biologists trucking bears back and forth.”
Access to these habitats is important for the grizzly’s survival, Pearson said.
“Climate change is going to change food sources, which we’ve already seen with whitebark pine,” he said. “Bears are going to need to be able to move and disperse across a wider range of habitats.”
The recent grizzly sightings outside of vast expanses of wilderness — places like the Big Horn Basin desert that are considered by most biologists to be marginal habitat — are probably explained by young adult males, Bruscino said.
“That’s a well-understood behavior in young [male] bears,” he said. “They also move around considerably before they set up a home range. That bear may or may not decide that’s a place where he wants to live.”
The urge to set up shop far away from his mother and siblings might be how a grizzly male avoids mating with close relatives, Schwartz said.
“When a mother has offspring, the female offspring will set up a home range near their mother,” he said. “Males, they leave their mother’s home range and go off some distance.
“There may be some advantage to prevent inbreeding,” he said. “What we’re seeing is a very natural process of grizzly bear biology.”
Although bears may seem out of place today, some of these locations historically might have made good grizzly habitat.
“The Great Plains were populated by something like 8 million bison,” Schwartz said. “Meat probably was an important food source for the grizzly bears living out on the Great Plains. Well, they’re gone.”
Instead, livestock and human developments occupy these spaces, Bruscino said.
“I think they just won’t succeed, because the potential for conflict is high in some of these places,” he said. “Grizzly bears succeed in big expanses of wild country.”
Even places such as the Bighorn Mountains, which might seem like good bear habitat, are used intensively for cattle and sheep grazing, Bruscino said.
“They’re probably dispersing into habitats that are no longer biologically suitable,” he said. “In the Greater Yellowstone Ecosystem, suitable grizzly bear habitat is kind of an island. Once they hit the beach, that’s that.
“They probably don’t belong there any more,” Schwartz said. “The land has been converted from a wild state. It’s occupied by humans. It’s no longer suitable for bears.”
For now, Wyoming Game and Fish bear managers must abide by the restrictions of the Endangered Species Act, Bruscino said.
“We have no ability to control where the bear population expands to,” he said. “All we can do is manage bears that cause damage to people or property, or preemptively move a bear that has the potential for conflict.”
That means more work for bear managers educating people about safe bear practices, including securing human foods and using pepper spray or some other means of defense in the backcountry.
“As the bear population expands, it ultimately requires more resources from the agency to collect information on the population and to manage bears,” Bruscino said.
The expanding population highlights the need to redouble efforts to educate people about the grizzlies, Pearson said.
“Trying to stay a step ahead of the bears ... will be important,” he said.