This image provided by the National Park Service shows a gray wolf in the wild.
The Humane Society of the United States provided a copy of the lawsuit to The Associated Press before its public announcement. The other plaintiffs include Born Free USA, Help Our Wolves Live and Friends of Animals and Their Environment.
Hunters and trappers in Minnesota and Wisconsin killed 530 wolves combined during those states' recently concluded seasons — 413 in Minnesota and 117 in Wisconsin. The Michigan Legislature voted in December to authorize wolf hunting, which could resume as early as this fall if the state's Natural Resources Commission approves.
"In the short time since federal protections have been removed, trophy hunters and trappers have killed hundreds of Great Lakes wolves under hostile state management programs that encourage dramatic reductions in wolf populations," Jonathan Lovvorn, chief counsel for animal protection litigation at the HSUS, said in a statement. "This decision rolls back the only line of defense for wolf populations, and paves the way for the same state-sponsored eradication policies that pushed this species to the brink of extinction in the first place.
U.S. Fish and Wildlife Service spokeswomen did not immediately respond to messages seeking comment, nor did officials with the Minnesota, Wisconsin and Michigan Departments of Natural Resources.
It's been more than 40 years since the federal government imposed protections to prevent wolves from going extinct in the lower 48 states. Gray wolves recovered to more than 4,000 combined in the western Great Lakes and northern Rocky Mountain states by the time the government took them off the list in those areas in January 2012. That action followed several years of court battles and turned responsibility for managing their populations back to the states.
Minnesota had an estimated 3,000 wolves before they came of the endangered list, while Wisconsin and Michigan had about 850 and 700. The three states' management plans would allow a 50 percent decline in the region's population if hunting and trapping took it down to the minimum levels allowed under their plans, the lawsuit says.
"This drastic population decline would not only threaten the Great Lakes population, but it would prevent this population from serving as a source of dispersing wolves that could repopulate unoccupied portions of the wolf's range," the lawsuit says.
Environmentalists also have gone to court to try to restore federal protections to wolves in Wyoming.
Wildlife managers predicted before the inaugural seasons in Minnesota and Wisconsin that hunters would face stiff challenges in bagging the wary predators. It turned out not to be quite as difficult as expected. Minnesota and Wisconsin slightly exceeded their hunting-and-trapping targets of 400 and 116, respectively, but officials said those were just goals, not firm quotas, so exceeding them was not cause for concern.
Jayne Belsky / AP file
In this photo provided by Jayne Belsky via the Wisconsin Department of Natural Resources, a gray wolf is seen roaming a wooded area near Wisconsin Dells, Wis.