Montana is suing Yellowstone National Park over a plan to increase the number of bison in and around the park and establish greater tolerance for their presence outside its boundaries.

In a press release announcing the lawsuit, Montana Gov. Greg Gianforte criticized the National Park Service for how it developed the plan, describing the effort as an example of “federal overreach” and saying it was created without proper state consultation.

“The National Park Service has repeatedly and consistently failed to engage with the state in a meaningful and transparent manner as required by law throughout the planning process,” Gianforte said in the statement. “NPS has not given us a fair shake and has ignored concerns raised by the state.”

The state is asking the U.S. District Court to halt the plan’s implementation and send park administrators back to the drawing board to draft a new plan. The Montana Department of Livestock and Montana Fish, Wildlife, and Parks are also plaintiffs in the lawsuit, which alleges the National Park Service made procedural errors in developing the plan and failed to take into account the concerns of the livestock industry.

Wildlife advocates criticized the lawsuit, arguing that bison, America’s national mammal, belong on the landscape and that Montana had adequate opportunity to weigh in on the park’s proposal. More than 27,000 people commented on the plan, which was celebrated by some conservationists and disdained by others for the compromises it incorporated.

The plan, formally adopted earlier this year to replace a version enacted in  2000, directs wildlife managers to aim for a herd of 3,500-6,000 animals, a modest expansion of the population target established more than 20 years ago. It also calls for expanded bison hunting and gives bison greater flexibility to roam beyond the tolerance zones along the park’s northern and western edges. The latter change is supported by the Custer Gallatin National Forest, which manages much of the land adjacent to the park. 

Yellowstone bison have historically been confined to the park due to concern they may spread brucellosis, which can cause cattle to abort their young. But as the new plan notes, updated research has found that elk have transmitted brucellosis to cattle more than two dozen times since 2000, while there has not been a single recorded case of bison-to-cattle transmission of the disease. 

In the 51-page court filing, the state alleges the NPS developed the plan over a “break-neck” 1.5-year period without “meaningful consultation and collaboration” with the state and describes the plan as “NEPA deficient” — a reference to the National Environmental Policy Act. The lawsuit also argues that an overabundance of bison has reduced the park’s woody vegetation and diminished its biodiversity. It criticizes a plan component that increases the number of bison transferred to tribal governments around the country, arguing the expansion merited a more rigorous review, and takes issue with the abandonment of a bison brucellosis vaccination program the 2000 plan included.

A spokesperson for Yellowstone National Park said the park service will review the lawsuit “and let the legal process play out.”

Montana state Sen. Pat Flowers, D-Belgrade, said he’s disappointed that bison management is returning to the courtroom, describing the state’s litigation as a time- and money-intensive step backward in bison management.

Flowers also described FWP’s participation in the lawsuit as “puzzling.”

“I don’t understand the dog they have in this fight,” he said. “I think their advocacy should be [for] managing bison as wildlife, recognizing there are some challenges there with the risk of brucellosis.”

Like the Montana Department of Livestock, the Montana Stockgrowers Association has been critical of the park’s proposal. The association expressed concerns that expanding the overall bison population will lead to more migration out of the park, increasing the risk of brucellosis transmission to cattle and stressing the park’s available forage.

In an email to MTFP, Buffalo Field Campaign Habitat Coordinator Darrell Geist criticized the state’s motivation for filing the lawsuit.

“Gov. Gianforte is aiming to significantly reduce the bison population so very few, if any, remain to migrate onto millions of acres of National Forest habitat elk freely roam,” Geist said. “It’s about the state exerting control over Yellowstone National Park and diminishing the most significant wild bison population remaining in the United States.”

In a text to MTFP, Michelle Uberuaga with the National Parks Conservation Association described the park’s plan as a workable compromise.

“Buffalo belong on the land, they are an integral part of a healthy and wild Yellowstone,” she wrote. “The park’s plan balanced many competing interests and the state of Montana had ample opportunity to provide input.”

The plan was developed amidst several years of tumult in bison management across multiple agencies.

Early last year, a tribal hunter was grazed by an errant bullet while harvesting a bison just north of Yellowstone’s boundary. The particularly harsh winter of 2022-23 drove bison out of the park in droves in search of forage, allowing hunters to kill 1,067 animals, a record. 

Montana is also engaged in a multi-year fight with the Bureau of Land Management over its decision to issue bison grazing leases in north-central Montana to American Prairie. To the consternation of many of the state’s livestock producers, the nonprofit has been developing one of the country’s largest nature reserves, with bison a keystone species.