What happened to the grizzlies Wyoming trucked in from Montana to boost genetic diversity?

In the months after Grizzly 1126F hit the ground in Wyoming two summers ago, the young translocated bear went on an impressive walkabout that had state biologists eagerly watching her movements. 

And move she did.

“She moves everywhere,” said Dan Thompson, who leads large carnivore management for the Wyoming Game and Fish Department. 

Grizzly 1126F’s unique history ups the intrigue in her travels all over the map. The 4-year-old sow is one of two bears that were trucked south from Montana’s Northern Continental Divide Ecosystem in July 2024, along with Grizzly 1129M, a male. The translocation, partly in response to a federal judge’s 2018 ruling, was intended to increase the genetic diversity of the Greater Yellowstone Ecosystem’s population of grizzlies, which remains geographically isolated.  

So where’d Grizzly 1126F go after being captured near Montana’s Middle Fork Flathead River and deposited southwest of Togwotee Pass in the Blackrock Creek drainage? 

“She has made several loops around the entire ecosystem,” Thompson said. “Around Yellowstone, into Idaho, up toward Cody. Then she went down toward Jackson, Wilson, into Idaho again and came back across the north end of the Tetons.” 

The female grizzly has stopped, for now, to den at a remote site deep in the Teton Wilderness beyond the North Fork of the Buffalo Fork River, he said. 

Meanwhile, the translocated male has had the opposite proclivity since being turned loose along a remote shoreline of Yellowstone Lake. Grizzly 1129M basically stayed put. 

“He really has maintained a location in the southern half of Yellowstone, south of Yellowstone Lake,” Thompson said. 

Typically, males make big dispersals and females stay put — the opposite of what’s happened with the translocated grizzlies. It’s led biologists to joke that they missexed the two animals. They didn’t, Thompson said.

Ultimately, it’s not where grizzlies 1126F and 1129M go that’s most important to those biologists. It’s what they do: Ideally, other grizzlies. The goal is for them to reproduce.

“She should have bred this year,” Thompson said, “so it’ll be interesting to see if she has cubs this spring.” 

Grizzly bear crews that keep close tabs on the population will be monitoring to see if that’s the case. 

Ascertaining whether Grizzly 1129M has spread his genes will be less straightforward. The boar is also estimated to be 4 years old, which isn’t considered a “prime age,” Thompson said, but he still should have bred females in summer 2025.

“We can only discern that through DNA tests,” he said. 

Eventually, analyses of blood extracted during routine grizzly bear captures will be able to pinpoint bears on the landscape that have genetic markers from both the Greater Yellowstone and Northern Continental Divide populations.  

For now, Thompson and his fellow carnivore managers are just happy that both bears have stayed within the Yellowstone region and stayed out of trouble — neither has been involved in any known conflict.  

The translocation of two grizzlies was an interagency effort that’s related to the status of the species: Ursus arctos horribilis is classified as threatened under the Endangered Species Act. Populations in both western Montana’s Northern Continental Divide Ecosystem and the tri-state Greater Yellowstone Ecosystem are considered robust and have long exceeded goals, but about 35 miles separate the two populations and there has never been a proven case of a grizzly departing one recovery zone and breeding in another. (They’ve come close: In 2023, a Yellowstone ecosystem bear dispersed to the northeast and ended up in Montana’s Pryor Mountains.)

North Montana’s grizzlies are connected to a much larger Canadian population, and so specifically, biologists want to see new genetic material introduced to the isolated Yellowstone population. It’s unclear if that’s happened yet, but there are no grave concerns about inbred grizzlies.

“This was not because we were worried about the genetic vigor of the population,” Thompson said. 

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But the 2018 ruling from U.S. District Court Judge Dana Christensen, which overturned the states’ bid to manage and hunt grizzlies, cited concerns about the population’s long-term genetic health. The federal judge out of Montana faulted the U.S. Fish and Wildlife Service for not planning to intervene unless “the Greater Yellowstone grizzly’s genetic health is demonstrably weakened.”

“In short, the Service has failed to demonstrate that genetic diversity within the Greater Yellowstone Ecosystem, long-recognized as a threat to the Greater Yellowstone grizzly’s continued survival, has become a non-issue,” Christensen wrote. 

Seven years later, two grizzlies born in Northern Montana — 1126F and 1129M — are spending their winters in Wyoming den sites. Evidence that they’ve reproduced could be months away.