MISSOULA, Mont. - A federal judge heard arguments Tuesday on whether gray wolves in Montana and Idaho should be protected once more under the Endangered Species Act and whether those states can ensure the species won't be wiped out under their management.

Defenders of Wildlife, the Greater Yellowstone Coalition and other wildlife advocates sued the federal government after the U.S. Fish and Wildlife Service named wolves in the Northern Rockies a distinct population segment and removed them from the endangered species list in April 2009.

The Fish and Wildlife Service turned over wolf management to Montana and Idaho wildlife officials but left federal endangered species protections in place for wolves in Wyoming, where state law is considered hostile to the animals' survival.

Gray wolves were listed as endangered in 1974, but following a reintroduction program in the mid-1990s, there are now more than 1,700 in the Northern Rockies.

The population is one of the most well-studied and best-understood in the world, and the conclusion 15 years after reintroduction is that wolves will continue to survive under state management, Justice Department attorney Mike Eitel told U.S. District Judge Donald Molloy.

The only threat now is Wyoming's state laws, which does not offer protections against people killing wolves throughout most of the state, Eitel said.

Plaintiffs attorney Douglas Honnold told Molloy the government should not be able to split the level of protection between the states - the entire Northern Rockies population segment must be listed as endangered if a portion is considered endangered.

The plaintiffs also are challenging how the Fish and Wildlife Service determined its minimum recovery population - at least 100 wolves and 10 breeding pairs in each of the three states - and the biology behind how the wolf population should be distributed among those states.

"We hope the Fish and Wildlife Service will go back to the drawing board and come up with something that will work," Honnold said.

Both sides say Molloy's decision could shape whether the government can use political considerations, such as state laws and boundaries, in choosing how and where a species can be listed under the federal wildlife protection law.

Congress meant for the government to have flexibility in protecting species under the Endangered Species Act, and both the Bush administration and the Obama administration have approved the wolf decision by the Fish and Wildlife Service, Eitel said.

But Molloy told Eitel he was having trouble accepting that the Endangered Species Act allows wolves in Wyoming to be separated from the rest of its distinct population segment.

"I understand the practical argument, I understand the political argument. Those two things are very, very clear. But what I don't understand is the legal argument. That's not very clear," the judge said.

Attorneys representing Montana and Idaho assured the judge that their states' laws and regulations require them to manage viable wolf populations. Both states held wolf hunts last year, Montana's ending with 73 wolves killed and Idaho with 185 killed.

Both are considering expanding their quotas and the tactics allowed for this year's hunt.

At the end of 2009, there were at least 843 wolves in Idaho, 524 in Montana and 320 in Wyoming, with more in parts of Oregon and Washington state.

That's too many for some. The population boom has meant livestock losses for ranchers and competition for hunters for big game, such as elk.

More than a dozen people gathered outside the courthouse to drive home the point that wolves aren't welcome. One carried a sign that simply said, "Kill wolves."

Each side is asking Molloy to grant a summary judgment, which could end the court case before it goes to trial. Molloy said he will make a ruling "as quickly as I can."