Colorado files lawsuit challenging federal protection for Gunnison sage grouse

The state attorney general's office is already working on a legal challenge to the decision by the US Fish and Wildlife service to list the Gunnison sage-grouse as "threatened" under the endangered species act.

The Attorney General's Office filed a lawsuit against the Interior Department and the U.S. Fish and Wildlife Service on Tuesday, arguing that listing the bird as threatened was unwarranted.

The state says the Fish and Wildlife Service failed to rely on the best available science, consider conservation efforts by landowners and state and local governments and study the economic effects of the designation.

The Fish and Wildlife Service listed the bird as threatened in November, and about 5,000 remain, only in Colorado and Utah.

Some environmental groups also have sued, saying threatened status is too weak and the birds should be considered endangered, which carries stronger protections.

Federal protection could bring restrictions on agriculture and oil and gas wells.