How to Count Grizzlies
An intensive DNA study will help wildlife managers design better recovery strategies for the threatened bears.
To snag a grizzly bear, a mixture of decomposed fish guts and aged cattle blood works quite nicely, Kate Kendall has found. Kendall, a U.S. Geological Survey research ecologist, isn't interested in capturing entire animals, just snatches of hair for DNA studies. The gory concoction is applied on piles of forest debris, and barbed wire is stapled to surrounding trees. Tufts of fur catch when the enormous omnivores--males stand seven feet tall and top out at 600 pounds--investigate the alluring scent.
Kendall will be using this non-invasive sampling approach in northwestern Montana and northern Idaho this summer as part of a three-year study that began last year. The goal is to gain a more precise estimate of the grizzly population in the 1.7-million-acre Cabinet-Yaak ecosystem, one of six federally designated recovery zones for grizzlies, listed as threatened since 1975.
During the past three decades biologists have radio-collared a handful of bears in the Cabinet-Yaak ecosystem, and the U.S. Fish and Wildlife Service estimates that 40-45 grizzlies live in its recovery zone. Using a DNA-based approach should paint a clearer picture, not only by giving a more accurate countbut also by providing the gender breakdown and genetic diversity within the population. Kendall spearheaded a similar study in Montana's Northern Continental Divide ecosystem, collecting some 34,000 samples from 765 grizzlies--a number that turned out to be more than twice the previous population estimate.
"Grizzly bear recovery in the Cabinet-Yaak ecosystem is one of our highest priorities," says Paul Bradford, chair of the Selkirk/Cabinet-Yaak subcommittee of the Interagency Grizzly Bear Committee and supervisor of Montana's Kootenai National Forest. Other recovery zones, like the Northern Continental Divide and Yellowstone, have benefited from intensive, multimillion-dollar studies. "I think [this] DNA study will provide needed additional data that help us better understand the existing situation of the population, and help us design better recovery strategies," he says.
It's not just wildlife managers who are anxious to get a solid population number--local communities have a vested interest, too. "It's a huge management and economic question," says Kendall. "That's why it's so important to find out with certainty what the population status is right now, to have a good measure of trend, and to figure out if we're managing bears as well as we can to promote recovery."
Because of the bear's threatened status, some U.S. Forest Service roads have been closed to protect grizzly habitat, and logging and mining operations limited. In fact, many of the corporations, communities, and individuals affected by the restrictions are pitching in to fund the $1.7 million study, along with federal and state agencies.
"We think the numbers are higher than currently estimated--we're hearing from our friends and neighbors that they're running into grizzly bears more than they ever have," says Lincoln County commissioner Tony Berget. "We'd like to know how many are really out there so we can move forward and set a plan in motion to get these grizzlies recovered."
Besides setting up 395 baited hair trapsin 790 different locations, Kendall's team is putting barbed wire on natural bear rubs--trees and structures that the animals regularly shimmy up against, giving their backs and sides a good scratch.
Studying natural rubs has provided some fascinating insight. Using hair samples and remote cameras, Kendall has found that in some instances, several grizzlies use the same rub--just not all at the same time.
In addition to hair snags, sampling at existing rub trees is going to be especially important in the Cabinet-Yaak study, Kendall says.Biologists have been radio-collaring five or so bears annually for the past 28 years and those animals may be skittish of the snags. "There's a big avoidance issue with the hair traps--bears previously handled are less likely to go into them. So rub trees are going to be really important to help get a precise count."
Come June, 70 summer employees will be traversing the mountainous terrain of the Cabinet-Yaak, lugging five-liter containers of the blood lure to bait traps, and tacking barbed wire to natural rubs. "It's a huge, huge effort," says Kendall. And one that could prove hugely beneficial to the grizzly's recovery.
For more on the Cabinet-Yaak grizzly DNA study, and for more videos and photos, click here.