The American bison is the largest land mammal in North America and, since 2016, the national mammal of the United States. Tens of millions once roamed the continent, but hunting cut the U.S. population to just 541 animals by 1889 before conservation brought them back. Many Americans call it a buffalo.
Appearance
- Appearance
- A huge shoulder hump, shaggy dark-brown winter coat, and lighter summer coat. Both sexes have short curved horns. Bulls weigh up to 2,000 lb (900 kg) and cows up to 1,000 lb (450 kg).
Where it lives
- Typical habitats
- Prairies and grasslands
- Mountain valleys
- Forest edges
- Range
- Once ranged from Alaska to the Gulf of Mexico and east to the Atlantic seaboard. Today wild herds live in parts of the U.S., Canada, and Mexico, mostly in parks and reserves, alongside many commercial ranch herds. In the U.S., public herds include those in Yellowstone National Park (Wyoming, Montana, Idaho), Wind Cave National Park (South Dakota), and Utah's Henry Mountains.
- Preferred conditions
- Yellowstone National Park is the only place in the United States where bison have lived continuously since prehistoric times. Nearly 5,300 bison lived there in 2025. They use Hayden and Lamar valleys year-round, graze grasslands in summer, and in winter move to thermal areas and along the Madison River.
- Seasons
In Wyoming
Breeding Jul–Aug
Behavior
- Diet
- Grasses and sedges make up most of the diet; bison graze 9–11 hours a day.
- Activity
- Surprisingly agile: they can run up to 35 mph (56 km/h) and jump about 5 ft (1.5 m). They roll in dirt to fight biting flies and shed old fur.
- Social life
- Cows and calves form herds that bulls join. In Yellowstone, herds average about 20 in winter and about 200 in summer.
Life cycle
- Breeding season
- The runs from late July through August in Yellowstone, when bulls bellow, wallow, and fight.
- Gestation
- About 9–9½ months
- Litter size
- Usually 1 calf, born in late April or May
- Lifespan
- About 12–15 years in the wild; a few reach 20
Cautions
- Cautions
- Bison are dangerous to people who get too close. In Yellowstone from 1980 to 1999, bison injured more than three times as many people as bears did.
Name and classification
- About the name
- Long known as Bison bison, and still often written that way, the species is now placed by some classifications in the cattle genus as Bos bison. Two subspecies are recognized: the plains bison, smaller with a rounded hump, and the wood bison, larger with a taller, squarer hump. In American English both "bison" and "buffalo" are accepted.
Conservation
- IUCN Red List
- NTNear ThreatenedCould become threatened before long
- Status
- Most bison today live in commercial herds; truly wild herds are fewer, small, and scattered. Cattle genes from past crossbreeding and diseases such as bovine tuberculosis are ongoing concerns.
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