The U.S. Fish and Wildlife Service has a long tradition of scientific excellence and always uses the best-available science to inform its work to conserve fish, wildlife, plants, and their habitat for the benefit of the American public.
Created in 1903 by President Theodore Roosevelt, today's National Wildlife Refuge System protects habitats and wildlife across the country, from the Alaskan tundra to subtropical wetlands. Managed by the U.S. Fish and Wildlife Service, the Refuge System's 560-plus refuges cover more than 150 million acres and protect nearly 1,400 species of birds, mammals, reptiles, amphibians, and fish.
While national wildlife refuges were created to protect wildlife, they are for people too. Refuges are ideal places for people of all ages to explore and connect with the natural world. We invite you to learn more about and visit the national wildlife refuges and wetland management districts in Colorado, Kansas, Montana, Nebraska, North Dakota, South Dakota, Utah, and Wyoming.
The Mountain-Prairie Region's Office of Ecological Services (ES) works to restore and protect healthy populations of fish, wildlife, and plants and the environments upon which they depend. Using the best available science, ES personnel work with Federal, State, Tribal, local, and non-profit stakeholders, as well as private land owners, to avoid, minimize, and mitigate threats to our Nation's natural resources.
Providing leadership in the conservation of migratory bird habitat through partnerships, grants, and outreach for present and future generations. The Migratory Bird Program is responsible for maintaining healthy migratory bird populations for the benefit of the American people.
The U.S. Fish & Wildlife Service Fish and Aquatic Conservation Program in the Mountain-Prairie Region helps conserve, protect, and enhance aquatic resources and provides economically valuable recreational fishing to anglers across the country. The program comprises 12 National Fish Hatcheries.
Law enforcement is essential to virtually every aspect of wildlife conservation. The Office of Law Enforcement contributes to Service efforts to manage ecosystems, save endangered species, conserve migratory birds, preserve wildlife habitat, restore fisheries, combat invasive species, and promote international wildlife conservation.
External Affairs staff in the Mountain-Prairie Region of the U.S. Fish and Wildlife Service provides support to the regional office and field stations to communicate and facilitate information about the Service's programs to the public, media, Congress, Tribes, partners, and other stakeholders in the 8-state region.
When Lewis and Clark explored the West in the early 1800s, grizzly bears roamed across vast stretches of open and unpopulated land between the Pacific Ocean and the Great Plains. But when pioneers moved in, bears were persecuted and their numbers and range declined. As European settlement expanded over the next hundred years, towns and cities sprung up, and habitat for these large omnivores—along with their numbers—shrunk drastically. Of the many grizzly populations that were present in 1922, only six remained when they were listed by the Service in 1975 as a threatened species in the lower-48 states.
General Habitat Requirements
Good grizzly bear habitat provides all the components necessary for the species’ survival: food, cover, a place to den, solitude, and plenty of space. Prime grizzly bear habitat features a diversity of plants, which provides bears with a varied food supply of plants, insects, and animals.
Today, grizzly bears are only found in large tracts of relatively undisturbed land, and a clear relationship exists between the loss of grizzly bears and the destruction or fragmentation of their habitat. Bear researchers agree that the most crucial element in grizzly bear recovery is to secure adequate habitat.
The home range for one grizzly bear may encompass up to 600 square miles, so space is essential. Because grizzly bears can come into conflict with humans and our uses of the land, such as ranching or recreation, good bear habitat must offer some areas that are isolated from development or otherwise highly impacted by humans.
Roads likely pose the most imminent threat to grizzly habitat today, and the management of roads is one of the most powerful tools available to balance the needs of people with the needs of bears. In addition, the impacts of logging, mining, livestock grazing, and various forms of outdoor recreation in grizzly habitat can be mitigated through well-designed management programs.
Like humans, the grizzly bear is omnivorous and scavengers by nature, spending most of their waking hours searching for food. Grizzly bears are adaptable and may eat insects, a variety of flowering plants, roots, tubers, grasses, berries, small rodents, fish, carrion (roadkill and other dead animals), other meat sources (e.g. young and weakened animals), and even human garbage if it is easily accessible.
Grizzly bears are active and feeding for six to eight months in the spring, summer and fall of every year. During this time, they must consume large amounts of food in order to survive the winter. Bears in each ecosystem learn where and when particular foods are available through their personal experiences, and because of this, biologists have been able to learn and generally predict their seasonal distribution and movement.
Food Habits Through the Seasons
Grizzly bears emerge from their dens in the spring, between late March through May, when young vegetation begins growing. During the early months they move out of the snow to low elevation areas to feed on winter-killed animals, ants, grasses and sedges, clover, dandelion, cow parsnip, and other plants.
In the summer months of June through August, grizzly bears continue to eat flowering plants and dig for roots, tubers, and insects. Common summer food sources are thistle, fireweed, mushrooms, and moths in Yellowstone. In some areas, bears may prey for a few weeks on newly born elk, deer, and bison calves, until the young animals become too fast to be captured. In late summer, berry-producing shrubs provide a preferred food in some ecosystems.
In September and October, grizzly bears spend more and more time searching for food and eating. Berries, whitebark and limber pine nuts, insects, and starchy tubers and roots are important food sources that allow them to build up the fat reserves they need for winter hibernation, which begins in late October or November.
Grizzly bears in the Greater Yellowstone Ecosystem also enjoy whitebark pine cone seeds where they overlap with their home range, and some conservationists have questioned whether an abundant supply of whitebark pine was necessary for the survival of bears in this ecosystem. Research indicates that as opportunistic feeders, Yellowstone grizzly bears can maintain healthy population levels even with varying availability of whitebark pine.