CHEYENNE, Wyo. — Six conservation groups have filed a lawsuit challenging a recent federal government decision not to protect wolves in the northern U.S. Rocky Mountain region under the Endangered Species Act, arguing that states are exercising too much leeway to keep the predators' numbers to a minimum.

The groups sued the U.S. Department of the Interior, U.S. Fish and Wildlife Service and the directors of those agencies July 2 in U.S. District Court in Missoula, Montana.

The lawsuit follows a Fish and Wildlife Service decision in February to reject conservationists' requests to restore endangered species protections across the region. Wolves are in no danger of extinction as states seek to reduce their numbers through hunting, the agency found.

The Fish and Wildlife Service at the same time announced it would write a first-ever national recovery plan for wolves, with a target completion date of December 2025. Previously, the Fish and Wildlife Service pursued a region-by-region approach to wolf management.

The decision not to return wolves to endangered status in the region violated the Endangered Species Act by failing to properly analyze threats to wolves and rely on the best available science involving the animals, the six groups wrote in their lawsuit.

The lawsuit critiques state wolf management programs in the region. Montana and Idaho plan to sharply reduce wolf numbers while Wyoming allows wolves outside a designated sport hunting zone to be killed by a variety of means, according to the lawsuit.

The lawsuit singled out how a Wyoming man last winter ran down a wolf with a snowmobile, taped its mouth shut and brought it into a bar before killing it. The killing drew wide condemnation but only a $250 state fine for illegal possession of wildlife under Wyoming law.

The U.S. Fish and Wildlife Service didn't immediately respond to a request for comment on the lawsuit filed by Animal Wellness Action; the Center for a Humane Economy; Project Coyote, a project of the Earth Island Institute Inc.; the Kettle Range Conservation Group; Footloose Montana; and the Gallatin Wildlife Association.

''Rocky Mountain states have liberalized the legal killing of wolves and have also removed discretion from their fish and wildlife agencies, letting lawmakers run wild and unleashing ruthless campaigns to kill wolves by just about any and all means," Kate Chupka Schultz, senior attorney for Animal Wellness Action and the Center for a Humane Economy, said in a statement.

Wolves have been protected as an endangered species in the region off and on since they were first delisted in 2008. They were first listed in 1974 and populations were successfully reintroduced in Yellowstone National Park and Idaho in the mid-1990s.

They have been off the federal endangered species list in the northern U.S. Rockies since 2017.

The rejection of the conservation groups' petitions to relist wolves in February allowed state-run wolf hunts to continue in Idaho, Montana and Wyoming. Wolves also roam parts of California, Colorado, Oregon and Washington.

An estimated 2,800 wolves inhabit the seven states.