The National Park Service and the U.S. Forest Service have repeatedly violated their own mandates by hazing and slaughtering thousands of bison attempting to leave Yellowstone National Park, according to a coalition that filed a lawsuit Monday. 

The coalition, which consists of individuals, American Indian groups and conservation groups such as Buffalo Field Campaign and the Western Watersheds Project, say the federal government has largely let livestock interests dictate how they treat the species.

In the lawsuit, filed in U.S. district court in Montana, the groups cite a long list of complaints, some of them specifically implicating Gallatin National Forest.

“As a once widely ranging native species, wild bison are now almost exclusively limited to the [Greater Yellowstone Ecosystem], and migrate to or attempt to migrate to forests in the ecosystem,” the complaint states. “Without managing for the viability of this keystone species, the Forest Service is not providing for adequate and appropriate diversity of plant and animal species.”

Yellowstone officials are also faulted in court documents.

“The Park Service has participated in capture, slaughter and other activities intended to prevent bison from establishing viable populations outside of [Yellowstone],” the lawsuit says. “These actions have the effect of impairing and not conserving bison in the [Greater Yellowstone Ecosystem]. Since 2000, hundreds of bison have been captured inside YNP, with many of those captured sent to slaughter.” 

Stephany Seay, media coordinator for the Buffalo Field Campaign, said the lawsuit’s goal is to make more habitat available for bison outside the park.

“The agencies are not making [habitat] available for those bison,” she said. “They are mandated to provide habitat for native species on the land that they manage. They are absolutely failing in their mandates.”

“We want a fair hearing for bison in the federal courts,” Seay said. 

During the last decade, federal agencies working with the state of Montana have captured and shipped to slaughter more than 3,300 bison to prevent the spread of brucellosis to cattle.

The lawsuit asks for the National Park Service and Forest Service to be barred from participating in the slaughter program. It also says claims about the threat of brucellosis have been overstated.

“It’s crazy for me to think that in a state like Montana, where we are rich in wildlife and wildlands, that we don’t have room for bison,” said Tom Woodbury of the Western Watersheds Project.

In early 2008, when the bison population had topped 4,000 animals, more than 1,400 bison were captured and shipped to slaughter.

That same year, the Government Accountability Office released a scathing report admonishing federal agencies for failing to preserve Yellowstone’s bison.

Federal officials said they were keen to expand where bison could go — but not at the expense of raising risks of brucellosis transmission.

“We need to learn from those baby steps to see if we might apply those at a broader scale,” said Forest Service spokeswoman Marna Daley of Gallatin National Forest.

Elk also carry brucellosis and are considered the likely culprits in at least seven transmissions to cattle in the last decade.

However, the Yellowstone region’s estimated 100,000 elk are not subject to a slaughter policy.