More than 100 bison were transferred from Yellowstone National Park to the Fort Peck Indian Reservation in Montana/NPS file

More than 100 bison from Yellowstone National Park were transferred to the Fort Peck Indian Reservation in Montana in January, marking the greatest transfer of bison to the tribes so far and bringing to nearly 300 the number of bison that have gone to the Assiniboine and Sioux tribes at the reservation.

The shipments, which mark the largest relocation of live Yellowstone bison to American Indian tribes in history, are ongoing as the National Park Service seeks to find a solution to how best to manage the park's bison. While biologists last summer estimated the Yellowstone bison herds included 6,000 individuals, park officials believe Yellowstone could accommodate 10,000 bison.

In January, the park transferred 112 bison to the Fork Peck Reservation. Since 2019, 294 bison have been transferred from Yellowstone to the Assiniboine and Sioux Tribes at Fort Peck. Approximately 170 of those bison have then been further distributed to 23 tribes across 12 states in partnership with the InterTribal Buffalo Council.  

The bison transferred last month were a large family group of seven males, 53 females and 52 calves, according to a park release.

Before they were shipped to Fort Peck, the bison had completed Phases I & II of the brucellosis quarantine protocol at Yellowstone and the APHIS facilities. Brucella abortus, a bacterium thought to have reached the country from European livestock, can cause spontaneous abortions or stillbirths in bison and cattle. Until 2010, if two or more herds in a state contracted the disease, or if a single herd detected to carry the disease was not sent to slaughter, all herds in that state were blacklisted from markets. Today that blacklisting applies only to the affected herd.

In Yellowstone, upwards of 60 percent of bison are thought to have been exposed to brucellosis; the park’s herds are judged to be “chronically infested” with the disease. 

Yellowstone's bison are thought to have descended from a small handful of privately owned herds and one deep in Yellowstone's interior that escaped the "Great Slaughter" of the late 19th century that decimated bison. Those "foundational" herds were held by Charles Goodnight in Texas, Michel Pablo and Charles Allard in Montana, James McKay in Canada, Frederic Dupree in the Dakota Territory, Charles "Buffalo" Jones in Kansas, and William Temple Hornaday at the New York Zoological Park in New York City.

In 1870, it has been estimated, 2 million bison from the “southern herd,” found south of the main east-west railroad line that crossed the Great Plains, were killed. Two years later an average of 5,000 bison a day were being killed. While Yellowstone National Park was established that year, 1872, and its enabling legislation outlawed the wanton destruction of wildlife, there was no one to enforce that regulation until the U.S. Army arrived in 1886 to patrol the park.

By 1876, for all practical purposes, the southern herd was judged to be wiped out, and six years later the northern herd faced the same fate. Extinction for the species loomed in 1902, when, aside from some private herds such as the one Charles Goodnight had established on his Texas ranch, free-roaming bison numbers were thought to be as few as 100, with maybe two dozen in Yellowstone.

Today, brucellosis has created political repercussions as officials, particularly in Montana, don't want their cattle herds exposed to brucellosis. To address those concerns, quarantine was included as a possible tactic for bison management back in 2001 when the Interagency Bison Management Plan (IBMP) was signed by the Secretaries of Interior and Agriculture and the governor of Montana. The National Park Service formally pursued a quarantine program in 2014 by initiating a public planning process. The operational quarantine program was approved in May 2018.

However, the National Academy of Sciences concluded in a 2017 paper that elk, not bison, are the primary carrier for brucellosis transmission in the Greater Yellowstone Ecosystem.

“In tracing the genetic lineage of Brucella across the ecosystem and among species, elk are now recognized as a primary host for brucellosis and have been the major transmitter of B. abortus to cattle,” the Academy wrote that year. “All recent cases of brucellosis in GYA cattle are traceable genetically and epidemiologically to transmission from elk, not bison.” 

The only facilities that currently meet structural specifications and biosecurity requirements for bison quarantine are located at Stephens Creek in Yellowstone National Park, Corwin Springs in Montana, and the Fort Peck Reservation.

Under the quarantine program, bison must go through three phases to be certified as brucellosis-free:

• Phase I - Managers capture bison in or near the park during winter. Bison considered suitable for quarantine based on initial negative tests for brucellosis are isolated in double-fenced quarantine pastures and tested every 30-45 days until all bison test negative for two consecutive testing periods.
• Phase II - Bison in these individual test groups undergo brucellosis testing by age and sex requirements described in the 2003 Brucellosis Eradication: Uniform Methods and Rules (APHIS 91–45–013) and are certified as brucellosis-free.
• Phase III - Managers can transfer bison to other fenced pastures. In the new location, brucellosis tests are conducted at six and 12 months to provide additional assurance. Managers keep these bison separate from other animals at least until the six-month test is completed. Thereafter, managers can release these bison on public or tribal lands for conservation and cultural purposes.

The bison shipped to Fort Peck go through phase III there.

Yellowstone National Park partnered recently with Yellowstone Forever and the Greater Yellowstone Coalition to more than double the capacity of the  park's quarantine facility. The park and APHIS intend to enter 250 new animals into the program this winter.

“We greatly appreciate the tremendous number of partners who have come together to make the Bison Conservation Transfer Program a success,” said Yellowstone Superintendent Cam Sholly. “It is important we continue to look for opportunities to build on the success of this program in order to move larger numbers of disease-free bison to tribes across the country, while also achieving our future goal of eliminating shipments to slaughter."