Behaviorīison are mostly active during the day and at dusk, but may be active through the night. They can jump over objects about 5 feet (1.5 m) high and have excellent hearing, vision, and sense of smell. Bison are agile, strong swimmers, and can run 35 miles per hour (55 kph). 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. Both sexes have relatively short horns that curve upward, with male’s averaging slightly longer than those of adult females.Īll bison have a protruding shoulder hump. They are reddish-tan at birth and begin turning brown after 2-½ months. Calves of the year are born after 9 to 9-½ months of gestation. Males (2,000 lbs/900 kg) are larger than females (1,100 lbs/500 kg) and both are generally dark chocolate-brown in color, with long hair on their forelegs, head, and shoulders, but short, dense hair (1 in/3 cm) on their flanks and hindquarters. Reductions began again in the 2000s due to increasing numbers and litigation about migration into Montana.īull bison bellow during rutting season to display their dominance.īison are the largest land-dwelling mammal in North America.By 1968, herd reductions of bison ceased.For decades, bison numbers were reduced due to belief that they, along with elk and pronghorn, were over-grazing the park.Bison from private herds were used to establish a herd in northern Yellowstone.The US Army, who administered Yellowstone at the beginning of the 20th century, protected these bison from further poaching.By 1902, poachers reduced Yellowstone’s herd to about two dozen animals.In the 1800s, market hunting and the US Army nearly caused the extinction of the bison.Yellowstone is the only place in the lower 48 states to have a continuously free-ranging bison population since prehistoric times.

Can be aggressive, are agile, and can run up to 30 miles per hour.Mate in late July through August give birth to one calf in late April or May.May live 12–15 years, a few live as long as 20 years.Male (bull) weighs up to 2,000 pounds, female (cow) weighs up to 1,000 pounds.Blacktail Deer Plateau, Tower, and the Gardiner Basin. Winter: hydrothermal areas and along the Madison River.This includes two primary breeding herds: northern (~4,460) and central (~1,360). All of the interested parties bring their own wide-ranging values and objectives to the debate.Īround 5,900 bison counted in summer 2022. Conservation of wild bison is one of the most complex of Yellowstone’s resource issues. To prevent conflicts with ranching and other activities outside the park, the National Park Service (NPS) works with other federal, state, and tribal agencies to manage and develop policies for bison access to habitat in Montana. However, some Yellowstone bison are infected with brucellosis, a livestock disease that can be transmitted to wild bison and elk as well as to cattle through contact with infected fetal tissue. These behaviors have enabled the successful restoration of a population that was on the brink of extinction just over a century ago. They also exhibit wild behavior like their ancient ancestors, congregating during the breeding season to compete for mates, as well as migration and exploration that result in the use of new habitat areas. Unlike most other herds, this population has thousands of individuals that are allowed to roam relatively freely over the expansive landscape of Yellowstone National Park and some nearby areas of Montana. Yellowstone bison are exceptional because they comprise the nation’s largest bison population on public land. Yellowstone is the only place in the United States where bison (Bison bison) have lived continuously since prehistoric times.

Summer landscape photos