(CN) Warning the bison that once roamed the continental U.S. in the millions are at risk of extinction, three conservation organizations brought a federal complaint Wednesday requesting the animal be listed as a threatened or endangered species.

Buffalo Field Campaign, Friends of Animals and Western Watershed Project filed the claim against the U.S. Fish and Wildlife Service and Interior Secretary David Bernhardt. The three groups are represented by the Friends of Animals Wildlife Law Program.

The groups claim failure to grant the request could cause “irreparable ecological harm” to the bison’s natural habitat and the study of bison in Yellowstone National Park. They argue the bison play a “keystone role” in the Great Plains ecosystem and are imperiled by hunting and livestock grazing, infrastructure and climate change.

The claim also states that when bison wander outside the Yellowstone boundaries in migratory winter months, Montana state agencies in accordance with state plans for bison management may slaughter the animals.

Attorney Michael Harris said the defense does not want to list the bison as endangered because of political sensitivity on the issue.

“The protection of the bison is unfavorable in the Montana ranch lands,” Harris said. But he added the petition holds merit because the park is down to a small remnant of bison that could soon disappear.

From 2005 to 2014, the park’s bison herds declined rapidly from a population of 3,531 to 1,400.

The Western Watershed Project and Buffalo Field Campaign first submitted a petition to safeguard the species under the Endangered Species Act (ESA) in 2014 and again in 2015. When the Fish and Wildlife Service denied the petition in 2016, the organizations filed a lawsuit in response.

Judge Christopher Cooper issued a finding in 2018 that the FWS had failed to thoroughly evaluate the petition and thus acted arbitrarily in issuing a rejection of the petition. He ordered the agency conduct a new 90-day finding on the petition.

The defendant is now in violation of the ESA for failing to conduct a 90-day finding on the petition, the claim states.

Harris shared that when the organizations sent the U.S. Fish and Wildlife Service a 60-day notice of the lawsuit earlier this year, they were slow to respond, waiting until March.

“It was very much ‘We’ll get to it when we get to it,” he said.

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