In a ground-breaking study that used DNA from bear hair to count bears without having to see them or to capture them, U.S.Geological Survey researchers have preliminary results showing that there are an estimated 437 grizzly bears in the northern third portion of the Northern Continental Divide Ecosystem and an estimated 332 grizzly bears in Glacier National Park itself.
Because of statistical variation, the actual numbers of bears in the northern third of the NCDE may vary from 349 to 590 individual bears, and from 241 to 549 bears in Glacier National Park, said Katherine Kendall, the USGS bear researcher in charge of the study. Kendall's study site encompassed 2 million acres - the northern third of the NCDE, an area that stretches from the southern Canadian border to just north of Missoula, Montana (see http://www.mesc.usgs.gov/glacier/beardna.htm for study site boundaries).
Although bear numbers for the park are higher than the previous 1970's estimate of 200 grizzly bears in the park, Kendall cautions that because the 1970s estimate was based on bear sightings only, its numbers would not stand up under today's scientific standards for reliability.
"Because of this," said Kendall, "we can't use these new, more reliable numbers to say anything about trends, except that in relation to other grizzly populations in the United States, this population appears fairly healthy, with a high density of bears."
Glacier National Park Superintendent Suzanne Lewis said that the park was "very pleased" with the preliminary reports generated by Kendall's work. "It gives the National Park Service insight into the grizzly bear population in the Northern Continental Divide Ecosystem of northwestern Montana that we've never had."
Grizzly bears once roamed most of the North American continent, but habitat destruction and direct conflicts with humans have reduced their range by 99 percent in the lower 48 states (see historical and current range maps at http://www.mesc.usgs.gov/glacier/dna_detail.htm#Background). Today, researchers estimate that fewer than 1,000 grizzly bears remain south of the Canadian border.
The Northern Continental Divide Ecosystem is one of six grizzly bear recovery zones south of Canada, and at 6 million acres, supports the largest population of bears south of Canada. "We have a richer and wetter habitat, a habitat with more topographic variation than the recovery areas to the south," said Kendall.
Bears in the Northern Continental Divide Ecosystem are connected genetically with bears across the border in Canada. This also gives the NCDE better long-term prospects of retaining a viable population than other bear recovery zones in which bear populations are more isolated and thus may lose genetic diversity over time.
Kendall reached these new numbers by identifying species, sex and individuals from DNA extracted from bear hair and scats -- bear feces -- without handling bears, a innovative process friendlier to bears and to the scientists studying the large grizzlies. Previous grizzly bear population studies in forested habitats typically were accomplished with live capture, radio collars and aerial tracking of bears, which is expensive and disruptive to bears, as well as to park visitors.
In 1998, bears were lured to 620 systematically positioned "hair traps" by well-tested lures brewed from aged fish, cattle blood, and other goodies. When the bears investigate the sweet-smelling brew, they have to cross a strand of barbed wire that snags fur - and within that fur, the animal's specific identity as revealed through genotyping its DNA.
This year is the final field season of Kendall's DNA study of bears in the Glacier National Park Ecosystem. Between now and fall, another round of hair trapping and rub tree surveys will snag bear hair that, when genotyped, will allow Kendall to estimate the survival rate of bears between 1998 and 2000, an important factor to understand when managers set conservation actions and priorities. The DNA profiles of the individual bears will also allow resource managers to address future conservation issues by providing them with information on the degree of genetic variation, how the individual bears are related and the ratio of males to females. Glacier National Park Superintendent Lewis noted that the park was looking forward to the additional knowledge it would gain from Kendall's last field season.
Many partners participated in the research. All genetic analyses were performed at Dr. Lisette Waits' laboratory at the University of Idaho. Other partners in the study included Glacier National Park, Flathead National Forest, Kootenai National Forest, Lewis and Clark National Forest, Blackfeet Nation, and Montana Department of Natural Resource Conservation and Montana Fish, Wildlife and Parks. Canon Corporation, Earthwatch Institute, National Fish and Wildlife Foundation, and the National Park Foundation also supported the research.
As the nation's largest water, earth and biological science and civilian mapping agency, the USGS works in cooperation with more than 2,000 organizations across the country to provide reliable, impartial, scientific information to resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, contribute to the sound conservation, economic and physical development of the nation's natural resources, and enhance the quality of life by monitoring water, biological, energy and mineral resources.
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