Success & Controversy
The protection and recovery of bison in Yellowstone is one of the great triumphs of American conservation. In 1902, after years of market hunting and poaching, there were only two dozen bison left in Yellowstone. Over the next hundred years, park employees worked to bring this species back from the brink of extinction. We succeeded, and now face the challenge of helping to manage a rapidly growing population of migratory bison that frequently roam beyond our borders onto private land and land managed by other agencies.
Yellowstone’s bison population is growing; the park’s borders are not.
Due to high rates of survival and reproduction, the bison population increases by 10 to 17% every year (that’s ten times faster than the human population grows worldwide). Currently, predation by wolves and bears has little effect on the population. Unless bison are allowed to seasonally migrate into surrounding states like other wildlife, we will eventually reach a point where there are too many bison in too small a space (the current population is 5,500 animals). Allowing the bison population to grow indefinitely will cause overgrazing and possibly mass starvation of animals in Yellowstone, as well as larger migrations and greater conflict outside the park.
The state of Montana treats bison differently than other wildlife.
Bison are not allowed to move freely outside Yellowstone due to fears by livestock interests that they might transmit brucellosis to cattle and compete with cattle for grass, as well as concerns for human safety and property damage. These fears have resulted in Montana legislation that prohibits moving live bison to other conservation areas, leaving few options to control the population. For long-term conservation, Yellowstone bison need access to habitat outside the park. All other wildlife moves freely in and out of the park, including elk which is another species that carries brucellosis.
Hunting inside the park is not an option.
Hunting is prohibited in Yellowstone, which is why the park offers some of the best wildlife viewing in the world. Several groups want to open the park to bison hunting, but Yellowstone National Park managers strongly oppose this idea. Allowing hunting in Yellowstone would affect the behavior of animals and drastically change the experience people expect when they visit. This is not the future we want for Yellowstone, and we don't believe it's the future the public wants either.
Eight agencies play a role in making decisions about Yellowstone bison.
In 1995, Montana sued the National Park Service because bison were migrating out of the park onto state lands. A court-mediated settlement reached in 2000 created the Interagency Bison Management Plan, which set a population target of around 3,000 animals and established a cooperative effort to manage bison in and around Yellowstone. If you care about bison, we encourage you to learn more about the agencies and tribes that play a role in deciding their future.
Bison need to be managed.
Until there is more tolerance for bison outside Yellowstone, the population can only be controlled by hunting outside the park and capture near the park boundary. Captured bison are transferred to Native American tribes for slaughter and distribution of meat and hides to their members. We understand that many people are uncomfortable with the practice of capture and slaughter--we are too, but there are no other options at this time. We have proposed alternatives, like quarantine and expanded tolerance, but these actions are opposed by the Montana Department of Livestock and the Animal and Plant Health Inspection Service.
We work to maintain a viable, wild, migratory population of our national mammal.
Yellowstone provides one of the few places where bison live much like their ancestors did: unfenced, and unprotected from harsh winters, drought, or predation. Yellowstone bison also provide a physical link to those ancestors, and show no evidence of interbreeding with domestic cattle. They were declared our national mammal in 2016 because they’re a symbol of wild America, an important part of our heritage, and a key player in an ecosystem that’s much larger than a national park.
We want to send Yellowstone bison to other conservation areas.
Right now, it’s against state and federal laws to move wild bison exposed to brucellosis anywhere except to meat processing and research facilities. We’ve proposed to implement a quarantine program for bison in collaboration with the Assiniboine and Sioux tribes on the Fort Peck Reservation. From quarantine, animals that repeatedly test negative for brucellosis could be sent alive to other public, private, or tribal lands. Quarantine would reduce the need for capture/slaughter operations, and it would promote an even more robust population of Yellowstone bison across the country. The state of Montana and the Animal and Plant Health Inspection Service have opposed this proposal.
We need a new bison management plan.
While the existing plan has been effective at preventing brucellosis transmission and maintaining a viable population, we believe that we've outgrown it. New data about bison biology and disease prevalence are available, and public opinion is shifting toward more tolerance for bison in Montana. We need a new paradigm that recognizes bison as wildlife and gives them the ability to move more freely on suitable public lands outside the park.
What You Can Do
We encourage you to learn more about bison conservation. Read about the History of Bison Management, review some Questions & Answers about bison management, download a copy of Yellowstone Bison: Conserving an American Icon in Modern Society, or watch an extended video Q&A with our lead bison biologist.
What would you like to see? Get to know all the people and agencies for whom this issue is important, including state legislators, congressional representatives, and the members of the Interagency Bison Management Plan. We’ll need to work together to find a future that includes wild bison.