By Emily Senkosky, UM News Service
MISSOULA – In early 2025, the U.S. Fish and Wildlife Service will decide whether to delist some populations of grizzly bears in the U.S. Northern Rockies. As Montanans consider their future with grizzly bears, University of Montana scientists are helping inform the social, ecological and policy aspects of the dialogue.
Grizzlies are emblematic to the West and particularly to Montana, where most grizzly bears in the lower 48 call home. Thanks to species protections and concerted, collaborative conservation efforts, grizzly bear populations have increased since its listing on the Endangered Species Act in 1975. But with that recovery, more conflicts have arisen between grizzly bears and humans – from unsecured attractants leading to habituation, to livestock depredations and human-grizzly bear encounters that can threaten the safety of humans and grizzly bears alike.
The Montana Department of Fish, Wildlife and Parks recently released a new management plan for grizzly bears that would direct state management of the species if they are delisted by the USFWS. At this crossroads, Montanans have the opportunity to help define their future with grizzly bears, keeping both humans and bears in mind. UM researchers with the W.A. Franke College of Forestry and Conservation and the Montana Cooperative Wildlife Research Unit are assisting with the conversation.
The Once Wild West
The grizzly bear’s historic range once covered most of western North America, stretching from Alaska to Mexico and from the Pacific Ocean to the Mississippi River. But as Americans expanded their range West and sought to remove large carnivores from the landscape, grizzly bear numbers crashed – dwindling to less than 1,000 in the lower 48 before the ESA protected them.
When first listed on the ESA, Congress set the bar for delisting grizzly bears: recovery over a “significant” portion of its original range. Later in the 1993 Grizzly Bear Recovery Plan, six recovery areas were identified as having sufficient habitat quality to support a “revived” grizzly population.
These zones include the Greater Yellowstone Ecosystem, Northern Continental Divide Ecosystem, Cabinet-Yaak Ecosystem, Selkirk Ecosystem, North Cascades Ecosystem and Bitterroot Ecosystem.
Today, grizzlies only occupy about 6% of their original range and are established in four out of six recovery zones. However, grizzly bear populations remain absent within the Bitterroot and North Cascades ecosystems since their extirpation – or complete removal – in these areas in the 1900s.
The Bitterroot Ecosystem spans more than 5,800 square miles along the border of Idaho and Montana. In the early 2000s, USFWS planned to reintroduce grizzlies to the ecosystem, but action was never taken. Grizzly bears now appear to have made some headway into the area on their own, and in 2023 a federal district judge ordered USFWS to actively reconsider plans to reintroduce grizzly bears there.
Dr. Sarah Sells, a U.S. Geological Survey research ecologist with UM’s Montana Cooperative Wildlife Research Unit, recently authored a study with Dr. Cecily Costello, a Montana FWP grizzly bear research biologist, to identify habitat grizzly bears are most likely to use as they naturally repopulate the Bitterroot Ecosystem. Sells and Costello’s study, “Predicting future grizzly bear habitat use in the Bitterroot Ecosystem under recolonization and reintroduction scenarios,” highlights the potential for this recovery zone in the continued success story of grizzly bear conservation.
The Importance of the Bitterroot
Efforts to improve the genetic exchange between the two populations of grizzly bears in the Greater Yellowstone Ecosystem and Northern Continental Divide Ecosystem have been a critical lynchpin in the discourse surrounding the species’ recovery. Population exchange is a major factor when it comes to determining if a population is “genetically viable” – able to reproduce and maintain stability.
The risks of genetically isolated grizzly bear populations are a key concern. Without genetic interchange, populations are at risk of inbreeding, leading to malformations and a lack of resilience against environmental changes. Maintaining genetic variation is critical for wild populations to survive, reproduce and adapt to future habitat transitions, such as those caused by climate change.
Sells and Costello’s study expands on their previous research using movement data from 65 GPS collared bears in the Northern Continental Divide Ecosystem to predict habitat use across grizzly bears’ range as they recover. By using simulations to predict dispersal routes and habitat suitability in the Bitterroot Ecosystem, Sells and Costello’s research demonstrates how grizzly bears could move across the landscape. Their work suggests that the Bitterroot Ecosytem could serve as a natural bridge between the Northern Continental Divide and Greater Yellowstone populations.
“Reestablishing a population in the Bitterroot Ecosystem would make it that much more likely that the genetic flow could happen successfully, because they don’t have to get as far before they find another grizzly bear population to mix genes with,” Sells said.
