Federal officials may tweak how they manage the threatened desert tortoise in southern Utah and three other states.

It's been 18 years since the tortoise received federal protections and biologists still aren't sure if the measures are stopping the species' decline.

The U.S. Fish and Wildlife Service is proposing to change its management plan to focus on a more coordinated approach with federal, state and local officials.

Environmentalists, though, say the proposal is too weak and doesn't do enough to directly address threats such as urbanization, grazing and predators.