US federal wildlife officials are proposing to strip endangered species protections from the grey wolf populations in 48 states, citing significant increases in their numbers.

The decision, announced on Wednesday by David Bernhardt, the acting secretary of the Interior Department, is likely to set off another round of court battles.

Conservationists and biologists contend that some areas of the country, like the Adirondacks in New York and the southern Rocky Mountains, could be suitable habitats. But wolf populations in those regions are vulnerable and still need protection to recover.

The grey wolf populations had dwindled to about 1,000 in the Lower 48 states when they received protection under the Endangered Species Act in 1975. But since their reintroduction to various regions, mostly in the West, the wolves’ numbers have rebounded to about 5,000.

In a statement, the US Fish and Wildlife Service said: “Recovery of the grey wolf under the Endangered Species Act (ESA) is one of our nation’s great conservation successes, with the wolf joining other cherished species, such as the bald eagle, that have been brought back from the brink with the help of the ESA.”

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Mr Bernhardt made the de-listing proposal public on Wednesday in a speech to the North American Wildlife and Natural Resources Conference in Denver, but it is not yet official.

The proposed rule will be published in the Federal Register, with a period of time made available for public comment.

The Obama administration had also proposed removing the wolves’ endangered status in 2013, but federal courts rejected the move.

Even before Mr Bernhardt was named as acting secretary of the Interior Department, administration officials and Republicans in Congress had begun efforts to weaken the Endangered Species Act.

And Bernhardt has come under fire for potential conflicts in a debate over protections for the smelt, a tiny fish at the centre of one of the latest rounds of California’s water wars.

Once considered only a pest, wolves were extirpated from nearly all of their range through a campaign of bounty hunting, trapping, the killing of pups in the den with dynamite and even biological warfare as trappers introduced mange into wolf populations.

When the wolves received protection, much of the population was limited to northern Minnesota. In the mid-1990s, they were reintroduced into Yellowstone National Park and Idaho, where their numbers have taken off.

They have spread into neighbouring states, including Utah, Oregon, Washington and California.

As their numbers grew, ranchers have had to contend with wolves’ appetite for cattle and sheep.

And while hunters contend that wolves have decimated elk and other game in certain regions, conservationists point to the benefits that the predators provide: keeping deer, elk and other species in check and therefore reducing their effect on vegetation.

The National Cattlemen’s Beef Association applauded the plan for de-listing, and said it should have happened sooner.

In a joint statement, Jennifer Houston, president of the group, and Bob Skinner, president of the Public Lands Council, contended that the Endangered Species Act “rarely functions as Congress intended”.

“Radical environmental activists use an endless cycle of lawsuits and procedural tricks,” to thwart de-listing, they said.

The animals are prolific breeders and while they are hunted and trapped, they are managed by state wildlife agencies that limit how many can be killed.

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Losing the endangered status protection concerns conservationists, who worry that new populations won’t become established in areas where the wolf is present but not yet stable.

“Stripping protections from wolves now would halt further recovery from places where wolves once lived and could live again,” said Collette Adkins, carnivore conservation director for the Centre for Biological Diversity.

“Without protections in the Adirondacks or Maine or the southern Rockies we don’t have any hope of recovery.”