DNA study doubles bear census

The estimate is in: There were 765 grizzly bears roaming the Northern Continental Divide Ecosystem during the summer of 2004.

That's the official result of an ambitious and unprecedented genetic study of the largest grizzly bear population in the lower 48 states. The study will be published in the January edition of the Journal of Wildlife Management.

Kate Kendall, a researcher with the U.S. Geological Survey in Glacier National Park, revealed the results of the study to a group of about 100 people in the park's community building Tuesday.

"We're really excited to finally present the results of this project," said Kendall, who has discussed the project publicly many times but could not reveal the final population estimate until the study had been peer-reviewed and accepted for publication.

"Here it is," she said, projecting a slide showing the population estimate for the 7.8 million-acre study area: 294 males and 470 females for a total of 765 grizzly bears.

The study involved DNA analysis of 34,000 bear-hair samples, collected from scent-baited sites surrounded by barbed wire, and from rub trees that bears routinely use in the backcountry. The study identified 563 individual grizzly bears in the ecosystem, considered the minimum population count.

The ecosystem includes Glacier Park, the Bob Marshall Wilderness Complex and surrounding forest and range lands.

But running the numbers through a "mark-recapture" statistical analysis, the population was pegged at 765.

Kendall said the study produced a high "confidence interval" - basically a statistical statement that there is 95 percent certainty that the bear population ranged between 715 and 831 bears, with the mean at 765.

"This is two-and-a-half times the number of bears previously estimated to live in the area," Kendall said, referring to an earlier estimate of 250 to 350 bears that was based on observations of female bears with cubs.

The study produced a bounty of peripheral information on the population, revealing things such as varying bear densities and genetic variation within the study area. It found that there has been a tightening genetic connectivity between six genetically distinct sub-populations over time.

"Overall the general health of the population is good," Kendall said. "With diversity in the population levels seen in undisturbed populations in Canada and Alaska, there is no evidence that population size was ever severely reduced or that its connection to Canadian populations was broken. The genetic structure suggests that there has been population growth between 1976 and 2007."

However, researchers did find early signs that human development along U.S. 2 has started to inhibit breeding between bears north and south of the highway west of the Continental Divide.

A graph shows an indistinguishable mixing of bear genetics on both sides of the highway east of the divide, but far less west of the divide where there is denser development and traffic.

The study found the densest concentrations of grizzly bears in the interior of Glacier Park, with declining densities moving south into the Bob Marshall Wilderness Complex.

The study's main purpose - the population "snapshot" - will provide a baseline for determining how the overall population is faring in the future.

A companion study being led by Montana Fish, Wildlife and Parks is aimed at generating a statistical population trend by monitoring female bears fitted with GPS collars. The study focuses on births and mortalities of female bears and their offspring over a 10-year period.

The population study, costing $4.8 million, has been criticized by Republican presidential candidate John McCain as being an example of wasteful government spending.

But Montana political leaders, along with land and wildlife managers, have vigorously defended it as a breakthrough project and a necessary step in the eventual recovery of the Northern Continental Divide grizzly bears, which have been protected as threatened under the Endangered Species Act since 1975.

The Greater Yellowstone grizzly bear population, estimated at 400 to 600 bears, was delisted last year after more than 35 years of intensive study.

Kendall's project was a logistical mountain to climb for an army of more than 400 people in summer 2004. Hair samples were collected four times from 641 "cells" in a project area the size of Maryland and Delaware combined.

Volunteers and paid workers carried barbed wire, scent bait and other supplies deep into the backcountry, progressively locating snagging sites at higher elevations every two weeks.

"Some field crews were stationed more than 30 miles from the nearest road," Kendall noted.

The project involved more than a dozen state, federal and tribal agencies, along with nonprofit groups.

According to The Associated Press, the U.S. Fish and Wildlife Service, which is in charge of regulating endangered species, is currently reviewing the bears' status in Montana as part of a five-year review required by the Endangered Species Act.

The study's results will be a key piece of evidence used by biologists to determine whether the bear still needs federal protection, a conclusion due out early next year.

Reporter Jim Mann may be reached at 758-4407 or by e-mail at jmann@dailyinterlake.com