CHEYENNE, Wyo. — President Donald Trump's administration has opened the door to industry-friendly changes to a sweeping plan imposed by his predecessor to protect a ground-dwelling bird across vast areas of the U.S. West.

Wildlife advocates warned that the proposed changes would undercut a hard-won struggle to protect the greater sage grouse.

Representatives of the ranching and energy industries cheered the policy shift as needed to give states flexibility.

The recommended changes released Monday by Interior Secretary Ryan Zinke recognized for the first time the importance of livestock grazing on sage grouse habitat, said Jim Magagna, executive vice president of the Wyoming Stock Growers Association.

It also backed away from requirements to keep rangeland grasses and shrubs at a prescribed minimum height, which ranchers had complained was arbitrary.

"I was very pleased with what I saw there in terms of the tone," Magagna said.

Millions of sage grouse once populated the American West, but development, livestock grazing and an invasive grass that encourages wildfires has reduced the bird's population to fewer than 500,000.

The conservation plan that was years in the making affects 11 states, and just how much Zinke intends to tinker with it remains to be seen.

It was hashed out under President Barack Obama and unveiled in 2015 as a solution to keeping the bird off the endangered species list following a decadelong population decline caused by disease and pressure on habitat from energy development, grazing and wildfires.

The proposed changes, the result of a 60-day review by Zinke's agency, could give states wiggle room in areas such as setting population goals and drawing boundaries of recognized habitat.

Advocacy groups such as The Wilderness Society and National Wildlife Federation said the proposal was a backdoor attempt to allow unfettered oil and gas development that ignored previous scientific studies showing that drilling too close to breeding areas would harm the birds.

"Wholesale changes to the plans are not necessary and could derail years of hard work," federation President Collin O'Mara said in a statement. "We cannot fall victim to the false dichotomy that pits wildlife conservation against the administration's energy development goals."