Bison

The American bison is the largest land mammal in North America and the national mammal of the United States. Despite its iconic status, the American bison has a long and varied history in the U.S.

Plains bison are being restored to Native American and public lands across the U.S. These herds play a significant role in the health of our grasslands as they help create habitat for other animals and promote plant growth when they forage. They are also valued by Indigenous communities for cultural renewal. 

Why are bison imperiled?

More than 30 million bison once roamed North America. As a major food source, bison formed the basis of the economy for numerous Plains Indian societies. In the late 19th century, however, the U.S. government encouraged mass hunting of bison in an organized effort to destroy the livelihoods of Plains Indians. By the late 1800s, fewer than 1,000 bison remained and all Plains Indians were forced onto reservations.  

Today urbanization, agriculture and industrial development fragments their grassland habitat and climate change exacerbates this threat. Low genetic diversity among individual herds threatens the ecological restoration of bison. And human intolerance is also a threat to their survival.

Partners are united and working across North America, however, to restore the bison. One recent breakthrough in helping better manage today’s herds was when Colorado Governor Jared Polis signed the “Protect Wild Bison” bill in April 2025. The bill designated bison in Colorado as wildlife in addition to livestock. Dual listing gives Colorado Parks and Wildlife the ability to manage bison as a big game species, working with tribes as well as the federal Bureau of Land Management and agencies from bordering states. Herds along the Colorado-Utah border, for example, could be managed cooperatively between Colorado Parks and Wildlife, Utah, the federal Bureau of Land Management and the Ute Tribes.