Inside the Corwin Springs compound, government veterinarians draw blood from the necks of young bison for disease screening and clip off pieces of ears for genetic testing. Those that pass muster become eligible for relocation outside Yellowstone, which could occur as soon as this winter on American Indian reservations in Montana.
"Our goal is to put them back on the landscape across the country, wherever state agencies and tribes can manage them appropriately," said Jack Rhyan, a veterinarian with the U.S. Department of Agriculture, which operates the Corwin Springs compound with the state of Montana.
For bison advocates, the project is the first step toward their dream of thousands of wild bison again thundering across broad areas of the Great Plains and the Rocky Mountain West. Ranchers, however, consider it a potential nightmare driven by nostalgia and filled with risks.
"The 18th century is gone. It's not coming back," said Jason Camp, a Montana cattle rancher who wants bison confined to Yellowstone.
Once numbering in the tens of millions in North America, bison populations plummeted in the 19th century as settlers moved West and hunted the animals for food. Later, hired guns such as Buffalo Bill Cody killed bison by the thousands - both for sport and to supply hides to growing domestic and European markets.
By the 1880s, only about 500 bison were left.
To stave off extinction, Teddy Roosevelt and others looked to save the animals by concentrating them in Yellowstone National Park. This spring, there were about 2,100 wild bison in the park.
Overall, there are about 20,000 wild bison in places including the National Bison Refuge in Montana, South Dakota's Wind Cave National Park and Utah's Henry Mountains. Another 500,000 bison in North America are being raised commercially for meat.
For ranchers, the primary concern over expanding the territory wild bison can roam is the livestock disease brucellosis. While Yellowstone offers the most genetically pure stock of bison in the world, about half the animals have brucellosis - which can cause pregnant cattle to abort their calves.
"Until they have a handle on brucellosis in that buffalo herd, they shouldn't be talking about moving any buffalo around the state," said Camp, whose ranch sits about 60 miles from Yellowstone.
Even disease-free bison would pose a threat, he added, by competing with cattle for grazing land.
For the last two decades, state and federal officials have been capturing and killing a large number of bison that migrate outside the park to prevent an outbreak that would trigger serious and costly restrictions on the ranching industry. Cattle at two ranches in Montana and Wyoming, however, recently tested positive for the disease.
Researchers at Corwin Springs employ intensive screening to help allay disease concerns, although they acknowledge brucellosis can lay dormant for months or even years before showing up in a test.
"We had one bison we had tested four times and then we tested it again and it converted to positive," Rhyan said. "It's sneaky - it becomes latent and cooks along, and then all of a sudden it blows up."
Animals at the compound are kept under strict quarantine and tested for brucellosis up to a dozen times. Infected animals are sent to slaughter. The project costs about $130,000 annually, according to Montana officials.
On a recent day, state and federal veterinarians herded 40 bison through a cattle chute on the compound. Wild-eyed, the animals smashed against the chute's steel bars. They twisted and bucked until a veterinarian locked down a head brace to still their movements.
More veterinarians moved in, to draw blood and take skin samples.
Most of the 400-pound bison showed no sign of disease and were set loose. Six animals that tested positive for brucellosis were loaded onto a trailer bound for a nearby slaughter plant.
Three years into the project, the first batch of about 40 bison adults and calves are slated to be shipped out this winter. Once on the reservations, tribal leaders will take over management of the animals, which must be fenced off from livestock and other wildlife. After five years of additional brucellosis testing, the tribes can set loose those animals testing negative.
Tribes interested in the herds have been following the program closely. Ervin Carlson, a member of the Blackfeet tribe and president of the InterTribal Bison Cooperative, said he expected several tribes to submit proposals to take animals from the quarantined Yellowstone bison.
"Buffalo have always been a part of us, for our culture and a lot of our spirituality," Carlson said. "I'd like to see them just like other wildlife. They'd be able to roam free just as other wildlife are able to do."
At least three states also have expressed interest in bison, according to Keith Aune with the American Bison Society, who has been serving as a liaison between agencies involved in the quarantine project and parties interested in bison.
Once the bison are placed, the bison will be designated as wildlife and fall under state regulation. If one migrates off the reservation, it will still be considered wildlife and can be hunted only under state regulations. The tribes will be encouraged to manage bison numbers through hunting.
A group of scientists hope the Corwin Springs project is just the beginning of a new chapter for bison restoration in North America. This spring, in a paper published in the journal Conservation Biology, 28 scientists and bison advocates argued the small, isolated herds now dotting the West could grow over the next century to occupy vast swaths of North America, including sites in Montana, Wyoming, Colorado and New Mexico.
Kent Redford with the Wildlife Conservation Society in New York said the group wants to "broaden the scope" of bison conservation and move past the troubles at Yellowstone, where more than 1,600 bison were killed last winter by government wildlife agents and hunters after the animals migrated outside the park.
"There's no reason you couldn't have many more bison across a much broader area than is currently available," Redford said. "We've got Alaska to Mexico to talk about."
