Bison

male bison with six small birds on its back
Birds will perch on the backs of bison, looking for insects disturbed by their grazing.

NPS Photo / Kim Acker

 

Perhaps no other animal symbolizes the West as dramatically as the American bison. In prehistoric times millions of these animals roamed the North American Continent from the Great Slave Lake in northern Canada, south into Mexico and from coast to coast. No one knows how many bison there were, but the naturalist, Ernest Thompson Seton, estimated their numbers at sixty million when Columbus landed. They were part of the largest community of wild animals that the world has ever known. The National Park Service has played an important part in returning the bison to the Great Plains. Click here to view the YouTube video Restoring the Thunder: Bison conservation in the Great Plains National Parks about the restoration of the American bison to the Great Plains.

Explore the Timeline of the American Bison created by the U.S. Fish and Wildlife Service.

 
an adult male and female bison stand in an orange patch of dirt, their noses are orange with mud
Cows (left) are smaller and have less hair on their heads. Bulls (right) are much larger, more muscular, and have thicker hair on their heads and forelegs.

NPS Photo

Description


Bison are part of the family Bovidae, to which Asian buffalo, African buffalo and domestic cattle and goats belong. Because American bison resembled in some ways old world buffalo (Asian and African buffalo), early explorers to North America began to call them buffalo. Although it is a misnomer, the name buffalo is still used interchangeably with bison. One of the physical differences between the old world buffalo and the American bison is the large shoulder hump of the bison. This hump, along with a broad, massive head, short, thick neck and small hindquarters give the animal its rugged appearance.

The color and character of the bison's fur varies with the season. A mature bull in winter has a dark brown to black coat. The length of the hair measures up to sixteen inches on the forehead, ten inches on the forelegs, and only eight inches on the hindquarters. It is little wonder that bison, unlike domestic cattle, face into storms.

 
a young bison rubbing its neck against a metal stake, the stake is bending under the weight
In the spring, bison shed their winter coat and may use wallows, park signs, trail markers, and fence posts to help remove itchy loose fur.

NPS Photo

Behavior


The best description of a bison's temperament is unpredictable. They usually appear peaceful, unconcerned, even lazy, yet they may attack anything, often without warning or apparent reason. To a casual observer, a grazing bison appears slow and clumsy, but they can outrun and out-maneuver than all but the fleetest horse. They can move at speeds of up to 35 miles per hour and cover long distances at a lumbering gallop.

Their most obvious weapon is the horns that both males and females have. But their head, with its massive skull, can be used as a battering ram, effectively using the momentum produced by two thousand pounds moving at thirty miles per hour! The hind legs can also be used to kill or maim with devastating effect. At the time bison ran wild, they were rated second only to the Alaska brown bear as a potential killer, more dangerous than the grizzly bear. In the words of early naturalists, they were a dangerous, savage animal who feared no other animal and in prime condition could best any foe. A bull with lowered head, snorting and pawing the ground, with tail stiffly upraised, conveys a universal warning of danger to all nearby that is impossible to ignore!

Other activities of the bison include rubbing, rolling, and wallowing. 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.

Bison have poor eyesight but acute hearing and an excellent sense of smell. The sounds they make range from a pig-like grunt to an aggressive bellow.

 
Bison mother and calf graze in the grass
Calves stay with their mothers until they are about one year old.

NPS Photo

Reproduction


The rutting, or mating, season lasts from late June through early September with peak activity in July and August. At this time, the older bulls rejoin the herd and fight each other for breeding rights. The herd is very restless during the rut and this is when they are most dangerous.

Calves, born about nine months later in April or May, generally weigh 30 to 70 pounds. They have reddish-brown fur and do not have the conspicuous hump of the adult. After a few months, the fur begins to change to chocolate brown and the hump begins to develop.
 

Cultural Significance and Conservation


Wind Cave, also called Oniya Oshoka or Maka Oniye, is a significant place in the Lakota tradition. In Lakota oral tradition, not only were the first humans born from the cave, but the first bison came from the cave as well. This oral tradition highlights the close connection that plains tribes had, and continue to have, with bison.

In 1800, it was estimated there were 40 million bison, by 1883, there were few wild bison in the United States - most were in Yellowstone National Park. By 1900, there were less than a thousand left in North America. The majority of the forty million animals were killed in a fifty-five year period, beginning in 1830. Many people denounced the slaughter; few did anything to stop it. Fortunately, a small, devoted group of conservationists managed to save a few hundred.

In 1913, the American Bison Society sent 14 bison from the New York Zoological Gardens (now the Bronx Zoo) to Wind Cave. An additional six bison were sent to the park in 1916 from Yellowstone National Park. It is from these bison that Wind Cave's herd is descended from.

 
 

More About Bison in the National Parks

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    Last updated: October 22, 2020

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