CHEYENNE, Wyo. — A lot of Westerners are watching whether the U.S. Fish and Wildlife Service is about to pursue Endangered Species Act protection for the greater sage grouse.

A finding is expected by week’s end and the oil and gas, livestock and wind energy industries — to name the bigger interests concerned — all have an enormous stake in whatever the agency decides.

“It ranks right up there with the spotted owl and polar bear,” said Pat Deibert, a Fish and Wildlife biologist in Cheyenne who’s been closely involved in the listing decision.

Especially in Wyoming, officials don’t mince words about the potential effect. Wyoming is believed to be home to at least half of North America’s sage grouse. Vast expanses of Wyoming are sage grouse habitat, including the same areas of gas development that supply much of the nation’s heat and drive the state’s economy.

An endangered listing would be “absolutely devastating” by requiring sage grouse to be considered ahead of virtually any development in most of the state, said Ryan Lance, a deputy chief of staff to Gov. Dave Freudenthal.

“This would throw the whole state economy up in the air,” Lance said.

A brown, chicken-sized bird with pointed tail feathers, sage grouse can be found in 11 states and southern Canada. Besides Wyoming, they inhabit large portions of Nevada, Montana, Oregon and Idaho, and smaller areas in Colorado, Utah, California, Washington and the Dakotas.

Loss of the birds’ sagebrush habitat is their biggest problem by far, said Deibert, who indicated she knows what the finding will be but won’t say ahead of a formal announcement.

In Wyoming, habitat has been lost to gas wells, and related pipelines and roads. In northern Nevada, the problem is cheatgrass, an invasive species that causes frequent wildfires to burn up sagebrush and prevent it from growing back.

West Nile virus also has taken a heavy toll on sage grouse. The birds have little immunity to the disease, and in northeast Wyoming, coal-bed methane development has pumped millions of gallons of groundwater to the surface, creating breeding grounds for mosquitoes that transmit West Nile, Deibert said.

And the list of problems for sage grouse continues. Unnatural noise frightens them. Barbed-wire fences can be a deadly collision threat. Also, sage grouse don’t like to linger near structures such as power lines or wind turbines, fearing that predatory birds can perch on those high places.

“They just do not like us. That’s it,” Deibert said.