Grizzly bears (Ursus arctos horribilis) are a subspecies of brown bear found across North America, Europe, and Asia. They are distinguished by a prominent shoulder hump, a somewhat concave facial profile, and longer, less curved front claws compared to black bears. Their fur coloration varies from light brown to nearly black, often featuring silver or golden tips, giving them their “grizzled” appearance. Adult males typically weigh between 400 to 600 pounds, while females average 250 to 350 pounds in the contiguous United States.
Current Strongholds in the Lower 48 States
In the contiguous United States, grizzly bears are primarily concentrated in several isolated ecosystems within the Northern Rocky Mountains. The most robust population resides in the Greater Yellowstone Ecosystem (GYE), which spans parts of Wyoming, Montana, and Idaho. This ecosystem, encompassing Yellowstone and Grand Teton National Parks, supports an estimated 1,000 to 1,030 bears, inhabiting diverse landscapes including forests, subalpine meadows, and riparian areas.
Another significant population is found in the Northern Continental Divide Ecosystem (NCDE) in northwestern Montana, which includes Glacier National Park. This area is home to approximately 1,000 grizzly bears, thriving in a mix of dense forests, alpine terrain, and open grasslands. Smaller populations exist in the Cabinet-Yaak Ecosystem, straddling northwestern Montana and northern Idaho, and the Selkirk Mountains Ecosystem in northern Idaho. These areas offer rugged, forested habitats, with fewer than 50 individuals in the Cabinet-Yaak and Selkirk ecosystems. The North Cascades Ecosystem in northern Washington also contains some of the best remaining habitat, but its grizzly bear population is estimated to be fewer than ten individuals.
Historical Range and Decline
Historically, grizzly bears roamed extensively across western North America, with an estimated 50,000 individuals inhabiting the lower 48 states prior to 1800. Their range stretched from the Pacific Coast to the Great Plains, and as far south as central Mexico. They occupied a wide variety of habitats, including prairie grasslands, alpine meadows, coastal regions, and vast forest ecosystems. The Rocky Mountains, the Upper Missouri River, and California were particularly common areas for grizzlies.
The arrival of European settlers in the 1800s marked a decline for grizzly bear populations. They were perceived as a threat to livestock and human safety, leading to widespread hunting, poisoning, and trapping. Between 1850 and 1920, grizzly bears were eliminated from 95% of their original range in the contiguous United States. By the 1930s, their distribution was reduced to less than 2% of their former territory. This contraction left grizzlies primarily confined to isolated national parks and wilderness areas in Washington, Idaho, Montana, and Wyoming.
Conservation and Management of Grizzly Bear Populations
Conservation efforts for grizzly bears in the United States gained momentum with their listing as a threatened species under the Endangered Species Act (ESA) in 1975. This legal protection prohibits harming, harassing, or killing grizzly bears in the lower 48 states, and mandates recovery plans. The U.S. Fish and Wildlife Service, responsible for their oversight, identified six recovery ecosystems to guide these efforts.
Management strategies focus on habitat preservation, minimizing human-bear conflicts, and population monitoring. Agencies work to secure and maintain large, connected landscapes, including establishing protected areas and wildlife corridors that facilitate movement between isolated populations, promoting genetic diversity and overall population resilience. Conflict resolution programs are also implemented to reduce human-caused mortalities, a primary threat. This involves promoting bear-resistant food storage and managing attractants like garbage and livestock carcasses to prevent bears from becoming habituated to human food sources. Ongoing research provides data on bear behavior and population dynamics, informing adaptive management practices to ensure their long-term survival.