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. In fact, bison are the heaviest land animals in North America. 

Approximately 50 million bison once dominated the North American landscape, but habitat loss and unregulated shooting reduced the population to less than 1,000 by 1889. As of 2020, 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. Yellowstone National Park is the only place in the U.S. where bison have continuously lived since prehistoric times, and those bison are pure with no cattle genes.

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. Their coat is so well-insulated that snow can settle on it without melting. 

The head is heavy with short, curved 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 can weigh 30-70 pounds at birth and are normally orange-red, earning them the nickname "red dogs."

These large grazers feed on plains grasses, weeds, shrubs, and leafy plants. They regurgitate their food and chew it as cud before final digestion.

Bison are unpredictable and can be very dangerous. While appearing slow and docile, they are very agile and can run up to 35 mph. They are also strong swimmers. 

You can judge a bison’s mood by its tail. When it hangs down and switches naturally, the bison is usually calm. If the tail is standing straight up, watch out - the bison may be ready to charge!

At Fossil Rim, just before you enter the Front Gate - look to your right and you will likely see our bison in their pasture. Similar to rhinos, bison have poor eyesight with excellent senses of smell and hearing.


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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.