Yellowstone, Montana Officials Disagree on Bison Management

Once roaming the Great Plains in the tens of millions, the American bison is arguably one of the West’s most iconic species. After a near brush with extinction, roughly 20,500 Plains bison are now in conservation herds across North America, according to the U.S. Fish and Wildlife Service, a quarter of which call Yellowstone National Park home. Nearly a quarter million more live in commercial herds.

Yellowstone bison are comanaged by a handful of organizations, not all of whom agree on priorities and best practices. When they’re inside the park, bison are under the management of the National Park Service. But when herds migrate outside of park boundaries into Montana, control shifts to the Interagency Bison Management Plan, a group consisting of the Park Service and seven other federal, state and tribal organizations, that was created in 2000 as a result of a court-mediated settlement regarding management rights to Yellowstone bison.

At its annual fall meeting on Oct. 31, members of the interagency group expressed disapproval of a draft Environmental Impact Statement released in August by Yellowstone officials seeking to update the park’s bison management program. The statement is the first new guiding document to bison management since the IBMP was formed, and the park fielded thousands of public comments in response to the proposed initiatives.

“Historically, success in bison management has only occurred when NPS and the State have cooperated and managed together,” wrote Montana Gov. Greg Gianforte in a 17-page Oct. 10 letter that will be evaluated by the park alongside the nearly 30,000 public comments submitted. “YNP’s uncollaborative and obstinate posture is reminiscent of a time before the IBMP, when tensions between YNP and the State were high and litigation prevalent.” In a recent interview with Mountain Journal, former Yellowstone Superintendent Dan Wenk discussed the interagency tensions surrounding bison conservation and management before the IBMP, among other topics.

A staggering 27 percent of Yellowstone bison were killed or removed from the park last winter, resulting in an estimated low of 3,960 bison in May. Following a productive 2023 spring breeding season, the current population has rebounded to near the 10-year average of 4,890, according to a recent IBMP report. Although populations have seemingly recovered, the loss triggered alarm bells for park officials, prompting the draft EIS statement to suggest that IBMP groups should not remove more than 1,100 animals this upcoming winter.

Montana law limits where bison can move outside of the park, and the animals are valued by both state and tribal hunters. As such, management seeks to strike a balance between supporting a healthy population and avoiding mass migrations that could cause problems outside of the park, according to the IBMP website. A primary concern in Montana is the transmission of brucellosis, a harmful bacterial disease, from bison to livestock. New research, however, suggests that bison are no longer the brucellosis-transmitting culprits they’ve been made out to be.

“Brucellosis in [Greater Yellowstone] cattle are traceable genetically and epidemiologically to transmission from elk, not bison,” according to a 2020 study by the National Academies of Sciences, Engineering, and Medicine. It is new data and circumstances such as this that prompted Yellowstone to update its management protocol.

The primary ways the population is currently controlled is through hazing, tribal and state hunts outside of park boundaries, capture and transfer to tribes for shipment to slaughter, and capture for transfer to tribal herds following brucellosis testing through the Bison Conservation Transfer Program. Yellowstone’s EIS outlines three proposed options for future management.

Despite the data presented in the EIS, a slew of Montana state officials and organizations, including Gianforte, the Montana Department of Livestock, and Montana Fish, Wildlife and Parks, don’t believe Yellowstone’s plans would do enough to manage the population. The spread of brucellosis to Montana livestock is still of primary concern to officials.  

“In its haste to blame elk, YNP fails to address or examine how increased bison population and distribution will affect elk presence, movement, and distribution in [Greater Yellowstone] and thereby exacerbate the spread of brucellosis to other wildlife and livestock,” Gianforte wrote in his letter to the park.