Environmentalists are challenging a permit they say would allow federal and state wildlife managers to capture and hold captive certain wolves that find their way into the American Southwest from the north and from Mexico.
The Center for Biological Diversity filed its lawsuit against the U.S. Fish and Wildlife Service on Thursday. The agency did not immediately respond.
The group says it's seeking the protection of wolves found outside the area in New Mexico and Arizona where the federal government has been reintroducing endangered Mexican gray wolves.
Friday marks the 15th anniversary of the first release of captive-bred Mexican wolves as part of the reintroduction program.
There are now at least 75 of the predators in the wild in New Mexico and Arizona. Environmentalists argue that's far below what's needed for the population to be sustainable.