Getting To Know Montana's Black Bears

Rick Mace, FWP wildlife biologist

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While we knew a lot about black bears by the 1990s, one question troubled biologists and made bear management controversial. How many bears are out there, biologists wondered? Even in the 1990s no one knew exactly, because it was too expensive to mark and count bears.

All this changed with recent advances in genetic technology that make it possible to identify species, sex and individual animals from DNA extracted from animal’s hair.

In 2000, FWP embarked on a 10-year black bear population with plans to use DNA testing to mark and count bears.

We established a 500-square acre study area in the Swan Valley south of Big Fork. We will track the number of bears, age and sex structure of the population, harvest rates, and natural mortality rates over a 10-year period by marking and monitoring black bears using both radio telemetry and DNA analysis.

Here’s how it works. I use a small army of 30-40 volunteers every July—usually FWP biologists and other interested FWP employees—to put out barbed-wire hair traps or “corrals.”   We place a knee-high strand of barbed wire around four trees. In the corral center, we put fish and blood bait on a log.   Then we go away. Bears that come to investigate the site duck under the wire and leave a few strands of hair.

Several weeks later, we return to collect the tufts of hair and put each separate sample into a small coin envelope.   Each envelope has a unique number to track the location of where the hair sample was collected. The hair samples go to a genetic lab in Canada called Wildlife Genetics International in Nelson, B.C. for DNA analysis.

The results come back on a computer spreadsheet. The DNA marker and bear’s sex provided by the lab, combined with our location number on the envelope, identifies each individual bear.   I put the DNA marker number on the map where we collected that bear’s fur. If the hair sample in one envelope is a perfect match to that in another envelope, we know this bear visited two different locations and we can map those two locations using our location numbers from the envelopes.

In the summer of 2001, we identified 212 bears by their DNA. Then we looked at the 25-30 radio-collared bears in the area to see how bears tended to move in and out. We found, based on the exact movements of this smaller subset sample, that during black bear hunting seasons, about 85 percent, or 180 of the 212 bears, would be in the 500 square-acre study area.  

All bear hunters are required to bring their harvested bears to FWP for inspection of age and sex.   We also collect hair samples from these harvested bears. DNA results on the harvested bears in 2001 showed that only two of the harvested bears, or one percent, were from the group of 180 bears we knew to be in the area during the hunting season.   As it turns out, this is a very sustainable mortality rate.

We’re replicating this study all over Montana.   In the Swan Valley, we supplement our research with radio-collared bears, so we can calibrate bear movement and be the most exact there. But we have results now in the Yaak in northwestern Montana and the Big Snowy, Little Snowy and Judith mountains near Lewistown.   The goal is to put these research techniques to work in two additional places each year.

For the first time we will know with some certainty how many bears are in an area and, of those counted, how many are harvested each year.   We know black bear populations are able to sustain 10-12 percent harvest rates. So far, in the few areas we’ve studied, Montana’s harvest rates are in the single digits.  

Using DNA analysis to mark and track bears in this 10-year study will generate the information biologists need to sustain healthy bear populations.   Although it sounds high-tech, in practice it is a very useful tool for common-sense bear management.