Bison - bison bison - Video, Facts
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The bison is a member of the bovine family. Commonly called “buffalo” (which is actually a different species not found in North America), it is the largest land mammal in North America. There are two subspecies: the wood bison in northern Canada, and the plains bison which once roamed across much of the continent. The bison has a large head with relatively small, curving horns. Its dark brown coat is long and shaggy on the forequarters, including the front legs, neck, and shoulders, while the rest of the body has shorter, finer hair.
Fast Facts
Height: 6-6.5 feet at the shoulder.
Length: 10-12.5 feet.
Weight: 900-2,000 lbs; males are larger than females.
Lifespan: 18-22 years in the wild; over 30 years in captivity.
Bison are considered a keystone species: they once roamed the continent in great herds, and their grazing pressure helped shape the ecology of the Great Plains.
Diet
Bison mainly eat grasses and sedges.
Population
Did You Know?
The trails carved by animals like bison and deer in their seasonal migrations formed some of the earliest traceable paths into the American wildnerness, and were followed by Native Americans, explorers and pioneers.
Historically, bison numbered an estimated 20-30 million. Unregulated shooting of bison, which culminated in mass slaughters during the 1870s, reduced the population to 1,091 in 1889. Today, approximately 500,000 bison live across North America. Most are not pure bison but rather have been cross-bred with cattle in the past and are raised as livestock on ranches. Fewer than 30,000 bison are in conservation herds, and fewer than 5,000 are free-ranging and disease-free.
Range
Bison once roamed across much of North America. Today bison are ecologically extinct throughout most of their historic range, except for a few national parks and other small wildlife areas. Yellowstone National Park has the largest population of free-roaming plains bison (about 4,000), and Wood Buffalo National Park has the largest population of free-roaming wood bison (about 10,000). See a bison range map >>
Behavior
Bison move continuously as they eat so that they rarely overgraze an area. They historically roamed great distances. The females, or cows, lead family groups. Bulls remain solitary or in small groups for most of the year, but rejoin the group during mating season.
Did You Know?
A bison's thick fur offers great protection against the harsh elements of the American plains. Their winter coat is so thick and well insulated that snow can cover their backs without melting.
Bison often rub, roll, and wallow. Wallowing creates a saucer-like depression called a wallow. This wallow was once a common feature of the plains; usually these wallows are dust bowls without any vegetation. In winter, bison can dig through deep snow with their heads to reach the vegetation below.
Bison have poor eyesight, but have acute hearing and an excellent sense of smell. Bison can reach speeds of up to 35 mph.
Reproduction
Mating Season: June-September, peak activity in July-August.
Gestation: 270-285 days. Calf is born April-May.
Litter size: 1 calf.
Threats
Cross breeding with cattle threatens the genetic purity of bison. The few remaining genetically pure wild bison must be conserved separate from cross-bred bison to protect pure bison genes.
Today, the bison of Yellowstone National Park also face the threat of slaughter when they cross park boundaries and enter the state of Montana. The Montana Department of Agriculture fears the contamination of cattle by bison carrying the disease brucellosis, although there are no known cases of brucellosis passed by bison to domestic cattle in the wild.
Reasons For Hope
In April 2008, more than 50,000 Defenders activists wrote messages to Montana tourism officials expressing outrage over this senseless slaughter. In response, Montana Governor Brian Schweitzer announced a deal with Yellowstone National Park to create a much-needed winter corridor outside the park for these icons of the American West. This agreement – although not an ultimate solution – means that at least some bison will finally be able to leave the park when they need food to survive the winter.
Defenders at Work
To help overcome the challenges faced by American bison, several scientists, government agencies, tribes, first nations, and non-governmental organizations are working together to conserve North America’s bison. The Bison Specialist Group of the World Conservation Union’s Species Survival Commission is drafting a status report and conservation action plan for North American bison.
The document will serve as a benchmark against which to evaluate conservation and recovery into the future and will provide guidelines for reintroductions and management of public and private herds.
Defenders of Wildlife will work with several others to implement the guidelines of the completed action plan. In the meantime, Defenders is working now to protect Yellowstone’s bison herd from slaughter, and to restore or increase bison herds on public lands. Learn more >>
Legal Status/Protection
- Endangered Species Act (ESA): Wood Bison are listed as endangered. Plains bison are listed as under review.
- IUCN Red List: Bison are listed as near threatened.
- CITES: Wood bison are listed in Appendix II.
- Learn more about legal status and protection of bison >>
How You Can Help
- Help bison and other wildlife by adopting a bison at our Wildlife Adoption Center.
- Take Action for Wildlife at our Wildlife Action Center.
For additional information
- Visit Defenders' Imperiled Species: Bison pages for more information about what Defenders is doing to help.
