RENO, Nev. — The U.S. Fish and Wildlife Service is refusing to take the gray wolf off the list of endangered species in Nevada, even though agency biologists acknowledge the animals have been extinct in the state for decades.

In fact, while the University of Nevada's athletic teams are nicknamed the Wolf Pack, there's general agreement that the mountains and high desert valleys that boast mountain lions, black bears and bighorn sheep haven't been home to more than a handful of wolves for centuries.

The Nevada Division of Wildlife petitioned the federal agency to delist the wolf in Nevada, primarily to give the state more options to manage the wolf population in case the carnivores wander here after being reintroduced elsewhere.

In rejecting the petition earlier this month, the Fish and Wildlife Service said the Endangered Species Act makes it clear a species cannot be removed from the protected list unless it's documented the animal was listed in error and that either the species never existed or could not exist in an area because of unsuitable habitat.

"We agree with NDOW, that wolves never were abundant in the state, that there is limited habitat available for wolves in the state and that there probably never was a self-sustaining wolf population here," said Jody Brown, the federal agency's deputy field director for Nevada.

"So we don't dispute that there weren't high numbers historically. But that's not enough to say they never did exist or never could exist," she told The Associated Press.

Defenders of the wolf point to several American Indian tribes in Nevada who feature wolves in many of their stories and celebrations as evidence they must have once been a significant presence.

And despite the arid nature of most of the state, conservationists say there are significant parts of Nevada that someday could again support the creatures that once stretched across most of North America.

Neither federal nor state officials are sure the last time a gray wolf was confirmed in Nevada. In recent years, some ranchers in northeast Nevada claimed to have seen wolves, but they may have been coyotes.

State officials point to "Mammals of Nevada" — a book by E. Raymond Hall first published in 1946 — as the most authoritative source on the topic.

It confirms a sighting in extreme northwest Nevada in 1941 by Fred Vogel. Vogel had worked for the U.S. Bureau of Biological Survey killing wolves in the Great Plains and later killing coyotes in Nevada and therefore was presumed to be "competent to distinguish the northern wolf from the coyote," Hall wrote.