Young Grizzly Bear Moved to Cabinet-Yaak Ecosystem to Help Boost Population

Augmentation program preserving population, genetic diversity

By Tristan Scott
A young grizzly bear recently released in the Cabinet-Yaak Mountains to augment the ecosystem's sparse grizzly population. Courtesy FWP

The sparse population of grizzly bears in the rugged Cabinet-Yaak Mountains of Northwest Montana received a boost this month when wildlife officials released a young bruin into the remote ecosystem as part of an augmentation program.

On the morning of July 21, the two-and-a-half-year-old grizzly bear emerged from a culvert trap, stepped into the sunlight and entered the rugged Cabinet Mountains near the Montana-Idaho border, according to a press release from Montana Fish, Wildlife and Parks.

The 120-pound male marks the latest addition to a small-but-growing population of grizzly bears in the Cabinet-Yaak Ecosystem. It was the 20th grizzly bear moved to the region through an augmentation program that began in 1990 in an effort to save the population and boost genetic diversity. The last augmentation into the ecosystem occurred in 2016.

The latest grizzly bear did not have any prior conflicts with humans.

FWP officials, in collaboration with the U.S. Fish and Wildlife Service, captured the bear in a remote area near Stryker Basin in the Stillwater State Forest. They fitted the bear with a GPS radio collar for future monitoring and released him in a remote area west of Spar Lake in the Kootenai National Forest south of Troy.

The augmentation program continues to be a success in an ecosystem that saw its grizzly bear population nearly vanish 30 years ago. In 1988, biologists estimated fewer than 15 grizzly bears remained in the Cabinet-Yaak, which spans approximately 1,000 square miles in the Yaak River drainage and 1,620 square miles in the Cabinet Mountains.

“Knowing what we know now from sampling, I think that was actually a very generous estimate. The number of bears were probably in the single digits,” Wayne Kasworm, grizzly bear biologist for the U.S. Fish and Wildlife Service Cabinet-Yaak Ecosystem Program, stated in the press release.

Today, thanks largely to the augmentation program that Kasworm helped establish, there is an estimated 55-60 grizzly bears in the Cabinet-Yaak Ecosystem, with a projected growth rate of 2.1 percent annually.

Illustrating the intent and success of the program, the third bear moved through augmentation, a female in 1993, is responsible for at least 25 descendants through three generations. That female produced at least 10 first-generation offspring, which gave rise to at least 14 additional grizzly bears, and among those at least one offspring and counting.

“We are trying to increase the genetic structure of the population by bringing in unrelated individuals with no history of conflict,” Kim Annis, FWP grizzly bear management specialist, stated in the release. “We have a really good family tree for the Cabinet Mountains that shows we might possibly have lost the population altogether without having continued this augmentation program.”

The recovery goal is 100 grizzly bears in the Cabinet-Yaak and hopefully over time the animals will link with surrounding yet separate ecosystems, the Selkirk to the west, the Northern Continental Divide to the east, the Bitterroot to the south, and British Columbia to the north.

“The ultimate goal is to see bears move into the Cabinet Mountains and reproduce. We haven’t seen documented gene flow or reproduction, and only in the last few years have we seen minimal movement into the Cabinet Mountains,” Kasworm said. “That’s another step forward.”

The gender ratio of bears shows a slight preponderance of females in the Cabinet-Yaak, and while research shows that makes have been moving back and forth between the Yaak and Cabinets in recent years, the movement hasn’t resulted in reproduction.

“We don’t want to be moving bears with a pick-up truck forever. We want to encourage natural movement to help with gene flow and growing the population,” Kasworm told the Beacon. “That hasn’t really happened yet.”

Part of the problem is that the male grizzlies are moving between the main Cabinet Mountains and the Yaak during the fall rather than in spring, when breeding occurs. Another issue preventing reproduction could be the young bears aren’t yet competitive enough to successfully mate.

“Not only do you have to be there and be a competitive male, but you have to be there at the right time,” Kasworm said.