Courtesy of U.S. Fish and Wildlife Service Two Gunnison sage grouses face each other.

The U.S. Fish and Wildlife Service declared the Gunnison sage grouse a threatened species Wednesday. Under the Endangered Species Act, the habitat of the bird will be protected, which critics say could limit oil and natural gas development.

Dan Ashe, the agency's director, says that the bird is "still likely to face extinction in the future" and said that about 1.4 million acres will be designated as the species' critical habitat.

Gov. John Hickenlooper on Wednesday said Colorado will sue the federal government over the matter. He, and other Colorado political leaders, including Sen. Mark Udall, Sen. Michael Bennet, and U.S. Rep. Scott Tipton, roundly condemned the designation.

“I am deeply disappointed by the U.S. Fish and Wildlife Service's decision," Udall said in a statement. "Colorado's ranchers, conservationists, and state and local leaders have worked tirelessly together for more than 20 years to protect the Gunnison sage grouse, support local jobs and strengthen our special way of life."

Colorado politicians fear the listing could limit oil and gas development in western Colorado. But Ashe says that shouldn’t be a major issue.

"We don’t see a high potential for oil and gas development across the range of Gunnison grouse," he says. "So we don’t expect that to be a major source of conflict."

About 5,000 Gunnison sage grouse remain. The largest population, about 4,000 birds, lives in the Gunnison Basin of Colorado.

The designation of "threatened" and not "endangered" means the government will propose only regulations "necessary for the conservation of the species." Namely, it would grant exemptions for land owners to continue to ranch and farm in certain areas. A press release from WildEarth Guardians criticized that move.

“Imperiled by irresponsible grazing, oil and gas drilling, residential development, roads, powerlines and the cumulative impacts of these threats, the fewer than 5,000 remaining Gunnison sage grouse need the strongest possible protections to ensure they survive and recover,” said Erik Molvar, wildlife biologist with WildEarth Guardians.

State and local officials sought to delay the decision because they believe voluntary measures could help the bird.

The Gunnison sage grouse is related to the greater sage grouse, which is the focus of another debate about federal protections.