BILLINGS, Mont. — The federal government is proposing to lift threatened-species protections for hundreds of Yellowstone-area grizzlies, opening the door to future hunts for the fearsome bears across parts of three states for the first time since the 1970s.

The proposal caps a four-decade, government-sponsored effort to rebuild the grizzly population and follows the lifting of protections in recent years for more than a dozen other species, including the gray wolf, brown pelican and flying squirrel.

Hunting within Yellowstone National Park would still be prohibited. But the proposal could allow animals to be taken in surrounding parts of Montana, Idaho and Wyoming.

“By the time the curtain closes on the Obama administration, we are on track to have delisted more species due to recovery than all previous administrations combined,” U.S. Fish and Wildlife Service Director Dan Ashe told The Associated Press. “We’ve done that because of several decades of hard work, like with the grizzly bear.”

Grizzlies once roamed much of North America and came to symbolize the continent’s untamed wilderness. Hunters and trappers had nearly wiped them out across most of the Lower 48 by the late 1800s.

Thursday’s announcement came as conflicts between humans and grizzly bears have been on the rise, including six people fatally mauled since 2010. A record 59 bears were killed by humans last year, often by wildlife managers following attacks on livestock.

That’s resulted in pressure to turn over management of the animals to states, in part so hunting can be used to control the population. But wildlife advocates declared the government’s announcement premature and warned that it could reverse the species’ gains.

“There’s still a lot of uncertainty facing this population,” said Sylvia Fallon, senior scientist for the Natural Resources Defense Council.

A final decision on the proposal is due within a year. It could come sooner if state wildlife commissioners act quickly to adopt rules on how much hunting is allowed. Those rules are not mandatory under the federal proposal, federal officials said.

Montana Gov. Steve Bullock said the bear population would be responsibly managed by state wildlife officials. If a public hunt for the animals is pursued, the Democrat said, it could be done in a way that avoids killing bears that live on the periphery of Yellowstone.

“Yellowstone wildlife is treasured. We understand that. We’ll manage them in a way that addresses that sensitivity,” Bullock said.