A look at how Fish and Game studies the bear population in Unit 13

Updated: Jul. 16, 2021 at 7:00 AM AKDT
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ANCHORAGE, Alaska (KTUU) - Since last summer, Alaska Department of Fish and Game researchers have been studying the population density of bears in Game Management Unit 13 through a series of traps specially designed to collect hair samples in a non-invasive way. Through the study, they’re able to collect good data on the density of bears in the area and so much more.

Region 4 Research Coordinator Jeff Stetz said Fish and Game has been studying the bears in that area for some time. The data they collect is crucial to game management. Unit 13 covers are large area that includes a portion of Denali National Park, west of the Wrangell-St. Elias National Park & Preserve and north of Prince William Sound.

“There was a mandate from the Board of Game in the 1990s to reduce the density of bears in that area, Unit 13, by half,” Stetz explained. “This will be the third data point in the series to try and track how well harvest has been at reaching that objective.”

What researchers are doing is pretty simple. They place a pile of forest debris that looks like a cache out in the bush and coat it with a scent. In many cases it’s something like rotten cow blood, Stetz said. Around the cache is a single strand of barbed wire hung at about knee height.

The bear smells the blood, walks over the wire, and more likely than not leaves a good sample of hair for researchers to study.

“We come in and collect it two weeks later or so, send it to a lab, and get all this great information about these individuals,” Stetz said. “and all it takes is a couple of follicles to be able to identify species, sex, and individual ID.”

He said technology has come a long way in how they can study hair from the animals and all the information they can get from it. Stetz said they can also determine if the bear is stressed out by studying the hormones in the hair. They determine what bears have eaten recently by studying nearby scat, but they can tell what the bears have made staples in their diet in the long term through studying the hair.

There are some limitations though. For example, he said they can’t tell how old a bear is by hair alone, “but they’re getting there.”

Stetz said this work has been going on since summer 2020. Before then, and currently, he said they have been studying bears’ movement and population density through a collar tracking program.

He said that work involves researchers carefully immobilizing the bear with darts, and putting a GPS collar on the animal. They also do aerial surveys with the help of the tracking collars to help calculate density. Stetz said they hope to wrap up that part of the study next May.

Information from the collars and the hair traps will be used together to make more determinations on the bear density in Unit 13.

Stetz pointed out that some major benefits of the hair collection method are that they can track multiple bears in a given area, whereas live capture limits researchers to the one bear. Because researchers don’t have to immobilize the bears through the hair trap method, he said the bears’ behavior is completely unaffected by the study.

Another important note is that there is absolutely no food for the bears in the traps — just a scent. So Stetz said the bears aren’t being rewarded and thus, aren’t conditioned to look for food at the trap after going there once.

These traps are spread out all over the place in Unit 13, far away from camps and trails. Stetz said he’s never had a problem with a person stumbling across one of them, but should that happen, it’s advised that people leave them alone.

While the information researchers are learning about is fascinating in it of itself, Stetz said what they’re learning is crucial to managing the number of bears in the area and checking in on the mandate to reduce the population density there.

“Hypothetically if the density has been reduced passed that Board of Game objective ... they may change the harvest regulations for the area,” he said. “It’s information that the board can use to assess or make recommendations for management going forward.”

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