Scientific Name

Bison bison

Species Survival Plan



Open grasslands and prairies


Wolf, grizzly bear, coyote and man


Grasses and weeds

Originally Native To

North America


78 inches at hump


Male 2,200 lb.
Female 1,100 lb.


Distinct hump over shoulders; short, curved and black horns

Gestation Period

9 - 9.5 months


1 calf


Wild 15 - 20 years
Captivity 30 years

Social Behavior

Mixed-sex herds



Bison or Buffalo?

“Buffalo” is the term used by most people to describe the American bison. The term buffalo is believed to be derived from a name given to bison by early French explorers.

Bison and buffalo are members of the cattle family. True buffaloes are the Cape buffalo in Africa and the Asian water buffalo. Bison are found only in North America and Europe.

An estimated 20-30 million bison once dominated the North American landscape, but habitat loss and unregulated shooting reduced the population to just 1,091 by 1889. As of 2019, approximately 500,000 bison live across North America.

However, most of these are not pure wild bison, but have been crossbred with cattle in the past, and are semi-domesticated after being raised as livestock for many generations on ranches. Fewer than 30,000 wild bison are in conservation herds and fewer than 5,000 are unfenced and disease-free.

On May 9, 2016, President Obama signed the National Bison Legacy Act, making the bison our National Mammal. This was achieved through the efforts of the American Bison Coalition.

Bison are large, cow-like mammals with a distinct hump above their shoulders. The head, neck, shoulders and front legs are covered with shaggy hair, while the hind part of the body has short hair.

The head is heavy with short, curved and black horns. The tail is short, ending in a tuft of hair. The color of adults varies from light brown in summer to brownish-black in winter.

Bison calves average 35-50 pounds at birth and are normally reddish-brown, but some are black. Bison are unpredictable and can be very dangerous. While appearing slow and docile, they are agile and can run as fast as a horse.


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As a private nonprofit corporation, Fossil Rim does not receive national or state government support. Every cent spent or donated here goes in some way, directly or indirectly, toward the care of our animals.