The U.S. Fish and Wildlife Service decided to remove the gray wolf from the list in March, saying the species had recovered from near-extermination in the region. That transferred wolf management to Idaho, Wyoming and Montana, which are planning what would be the first public hunts in decades.

The lawsuit filed last week by 12 environmental and animal rights groups seeks to block the hunts, but the three states that filed paperwork with the court Monday and Tuesday hope to fend off the litigation so the hunts can proceed.

Officials from the states said Tuesday that they can be trusted to sustain wolves without federal oversight. The hunts, they said, are needed in part to control wolf packs that have been killing an increasing number of livestock.

"People have supported wolf recovery on the belief that being successful would mean a return of state authority over the animal," said Bob Lane, chief legal counsel for Montana Fish Wildlife and Parks.

At least 39 wolves already have been killed in the region since federal protection was lifted. Those deaths came under more relaxed rules for ranchers responding to livestock conflicts and a shoot-on-site designation for the predator across most of Wyoming.

An estimated 1,500 wolves now roam the three states. Federal biologists say that is much more than needed to sustain the species, but critics say only a larger population could prevent inbreeding and offset the impact of hunting.