Environmentalists say that amount of protection is still too low. Alan Ehrgott heads the American Rivers Conservancy. 

"I think not enough is being done to allow for the recovery of the frog. It’s not going to happen just with the designation of core habitat. It’s going to require some money and it’s going to require some active management."

Federal officials say they’ll work with ranchers who have populations of the threatened frog on their land to make their operations more compatible with the frog’s needs.

The Service said in its rule, “We believe that sensible ranching operations are compatible with California red-legged frog conservation and recovery, while alternate land uses such as high-density urban development, which could replace failed ranching operations, are not compatible.”   

The red-legged frog inspired Mark Twain’s short story “The Celebrated Jumping Frog of Calaveras County.”