About Bison
Yellowstone is the only place in the lower 48 States where free-ranging bison (Bison bison) have lived continuously since prehistoric times. This includes two primary breeding herds: northern and central. Male (bull) weighs up to 2,000 pounds, female (cow) weighs up to 1,000 pounds.
In the 1800s, market hunting and the US Army nearly caused the extinction of the bison. By 1902, poachers reduced Yellowstone’s herd to about two dozen animals. The US Army, who administered Yellowstone at the beginning of the 20th century, protected these bison from further poaching. For decades, bison numbers were reduced due to belief that they, along with elk and pronghorn, were over-grazing the park. In recent years, the bison population in Yellowstone has ranged from 3,500 to nearly 6,000.
All bison have a protruding shoulder hump. Large shoulder and neck muscles allow bison to swing their heads from side-to-side to clear snow from foraging patches, unlike other ungulates that scrape snow away with their front feet. Bison are agile, strong swimmers, and can run 35 miles per hour (55 kph). They can jump over objects about 5 feet (1.5 m) high and have excellent hearing, vision, and sense of smell.