When snow piles deep in Yellowstone's interior, bison go where it is shallower, and the easiest way down is the valley of the Yellowstone River toward Gardiner and the park's north gate. Some winters a few hundred animals make the trip, some winters far more. At the boundary they leave the protection of the park and walk into Montana, and into one of the longest-running fights in American wildlife management.
Yellowstone's bison are the herd the country nearly lost. They are the only bison in the United States that have lived wild in the same place since prehistoric times. By 1902 about two dozen were left in the park, and the herd rebuilt from those survivors and a small captive herd brought in to join them. Today it numbers in the thousands, more than five thousand in recent counts, more than the park's managers or the state of Montana want on the winter range.
The disease and the line
The trouble is brucellosis, a bacterial disease that can make pregnant cows abort and that probably reached the park's wildlife from cattle in the first place. Many Yellowstone bison carry antibodies to it, and Montana's livestock industry fears losing its disease-free status if the infection passes back into cattle. Under the Interagency Bison Management Plan, a partnership of federal, state and tribal governments, bison that leave the park in winter are hazed back, hunted or captured. Montana law forbids moving wild bison that may have been exposed to brucellosis anywhere but to slaughter or to research.
The capture pens are at Stephens Creek, inside the park a few miles northwest of Gardiner. In a hard winter the plan calls for removing several hundred animals. Some are taken by public hunters and by members of tribes with treaty hunting rights, who hunt along the boundary as their ancestors hunted bison in this country. Many of the captured animals have gone to slaughter, the meat and hides distributed to tribes.
A way out
For decades there was no third choice. A quarantine program, approved in May 2018, created one: bison captured at Stephens Creek that test negative are held and tested again and again, for one to three years, until they can be certified free of the disease. On August 23, 2019, the first fifty-five, all bulls, were trucked across the state to the Assiniboine and Sioux Tribes of the Fort Peck Reservation, at Poplar on the Hi-Line, where they finished their testing. In January 2023 a load of 112 cows, calves and bulls made the largest single transfer yet, and another 116 followed in February 2024, bringing the total to 414. An expansion of the Stephens Creek quarantine pens, opened in July 2023, more than doubled what the park could handle; the winter before, a record 282 animals had entered the program.
Fort Peck does not keep them all. The tribes and the InterTribal Buffalo Council pass the certified animals on to tribal nations across the country; Yellowstone bison from Fort Peck have gone as far as Alaska. It is the largest return of live Yellowstone bison to tribes in history.
In winter, drivers coming into Gardiner sometimes meet bison on the road and on the flats around the stone arch at the town's edge. Give them room. They are wild animals, faster than they look, on either side of the line.