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The bison, once a national icon, are Ice Age survivors and once their population numbered 30-60 million in North America.  Today, the total wildlife one hundred percent bison population in North America is estimated at 20,504.  No other species has declined this quickly.

Bison were hunted almost to extinction in the 19th century. Less than 100 remained in the wild by the late 1880s. They were hunted for their skins and tongues, with the rest of the animal left behind to decay on the ground.

The plains bison is the largest land mammal in North America.  Bison’s can weigh from 700 to 2,000 pounds and are between 7 and 12 feet in length. 

An overall small population of bison managed as wildlife in North America, and small herd size among them, contributes to ongoing loss of genetic diversity. Therefore, long-term conservation of existing diversity is at risk.

Known for roaming great distances, bison move continuously as they eat. 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.

Dominant bulls follow the cow around until the cow chooses to mate During this period, the bull blocks the cow’s vision so that she may not see other competing bulls, and bellows at males striving for the cow’s attention. June through September is the mating season, with peak activity in July and August. The cow’s pregnancy averages between 270-285 days, with calves being born in April and May.  The litter size is one calf.

Bison With Her Calf

Today there are only two public bison herds that have not shown evidence of interbreeding with cattle, which was done in order to produce heartier livestock. This has contributed to the “near threatened” status of the bison. The two herds exist in Yellowstone National Park and Elk Island National Park in Canada.  The largest wild herd of approximately 4,500 individuals is in Yellowstone National Park.

Bison are among the most dangerous animals encountered by visitors to the various North American national parks and will attack humans if provoked. They appear slow because of their lethargic movements, but can easily outrun humans; bison have been observed running as fast as 40 mph. A bison can do a standing jump over six feet straight up.

Efforts are being made to establish additional herds elsewhere to safeguard these valuable genetics and species should a catastrophic event such as  a disease outbreak threaten the herds. Several Native American tribes are working with World Wilde Fund (WWF) to grow bison numbers once again across the vast grasslands under their management.

Yellowstone National Park

The American bison played an important role in the ecology of the Great Plains.They graze heavily on native grasses and disturb the soil with their hooves, allowing many plant and animal species to flourish. 

Bison are adapted to the extreme weather conditions of the Great Plains, from summer heat to winter cold and blizzards. In winter, bison can dig through deep snow with their heads to reach the vegetation below.

The greatest threat to the bison is the refusal of some humans to accept them.  Habitat loss of the grasslands to urban development and agriculture is also a major contributor to the decline of the species. Only eight percent of all grasslands on earth are protected.  If bison are ever to reclaim their place on the Great Plains, serious efforts need to be made to secure safe habitat for them, and to combat the intolerance toward this animal.

WWF is promoting various Bison Adoption Kits if you would be interested in helping preserve part of America’s history and the American Prairie. The world’s leading conservation organization, WWF, works in 100 countries and is supported by more than one million members in the United States and close to five million globally.

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