An American bison is a cattle relative with a prominent shoulder hump. It mainly eats grasses and lives in herds.
Long hair covers the head and shoulders, while the hindquarters have shorter hair. Both sexes have short, upward-curving horns.
American bison graze in herds and repeatedly return to grasslands. Heavily grazed patches develop short, dense vegetation.
A study published in 2019 examined bison effects on grasslands in Yellowstone, USA. During 2012–2017 researchers established thirty one-hectare sites in areas frequently used during spring movements. They compared grazed plots with fenced plots protected from grazing, measuring plant biomass and the composition of leaves and stems.
In the most intensively grazed areas, animals removed more than half the available plant tissue. Vegetation remained short and dense, however, and during mid-to-late summer its nitrogen-to-carbon ratio was higher than in protected plots. Researchers used that ratio as an indicator of forage quality. Differences between grazed and protected patches revealed the relationship between feeding bison and the vegetation that continued growing afterward.
An extinction-risk assessment has not been added yet.
Yellowstone bison move outside the park seeking winter forage. Their movements beyond the boundary are restricted because of concerns including disease transmission to cattle and competition for grazing. The National Park Service works with states and Tribal partners on conservation and management. Its live-animal conservation transfer program uses quarantine and repeated testing. Animals certified as free of brucellosis are moved to the Fort Peck Tribes for additional testing; some are subsequently distributed to other Tribes to support herd restoration.