Threats to Grizzly Bears
Human-related deaths and habitat loss remain significant threats to long-term grizzly bear recovery. During the 1800s, an estimated 50,000 grizzly bears roamed from the Canadian border to Mexico and from the Pacific coast to the Great Plains. Today, grizzly bears in the lower 48 states are relegated to less than two percent of their former range. Grizzly bear populations in some areas are increasing and expansion is occurring back into portions of their historic range, like the plains of the Rocky Mountain Front in Montana. The future of our grizzly bear population relies on people accepting the presence of grizzlies and finding ways to coexist with this charismatic species.
The greatest threat facing grizzly bear populations today are deaths caused by humans. In an increasingly developed world, bears often cross through private lands in search of food and secure habitat. Attractants such as bee yards, garbage, fruit trees, chicken coops, livestock and birdfeeders often lure bears close to homes and habituate them, or help them become used to human activity. Bears that become used to living and feeding near human activity may be deemed a threat and then killed by wildlife officials or the private landowner. Often, these situations are avoidable.
Grizzly bears require large amounts of secure habitat, but in today’s reality, grizzly bears must routinely navigate roads, subdivisions, livestock operations and energy development. It is common knowledge that roads have a negative impact on grizzly bear survival. The remaining grizzly bear populations are unconnected, with major towns, roads and railways placed between them. Grizzlies need secure habitat to roam and reconnect the isolated populations like Yellowstone. It will be critical to the future of grizzly bears to identify and protect viable linkage corridors to ensure multiple, disconnected grizzly bear populations can someday be one.
Climate change poses new and little understood challenges to the bears. There is evidence suggesting that bears are denning later, and staying on the landscape longer in the fall when unintended shootings by hunters are most common. Most importantly, a changing climate can also impact food resources for grizzlies.
For example, whitebark pine seeds are a major food source for grizzly bears in the Yellowstone Ecosystem. Blister rust (an exotic species) and mountain pine beetle infections, exacerbated by climate change, are major threats to whitebark pine. Grizzly bears have shown that they can be adaptable to changing food conditions. However, this can occasionally lead them to seek out sources of food that can come from humans, like garbage, domestic fruit trees and livestock. Grizzly bears that choose to adapt to human-generated food resources often die as a result. What a grizzly bear’s environment and diet will look like in the face of climate change is still uncertain, and as habitats are altered we will have to continually assess the impacts to grizzly bears.
Lower 48 Grizzly Bears
Height: 3- 3 ½ feet at shoulders.
Length: 6-7 feet.
Weight: Adult males 300 - 850 lbs; females 200 - 450 lbs.
Top speed 35 mph.
Lifespan 20 - 25 years.