The Tucson shovel-nosed snake has suffered from habitat loss, urbanization and agricultural growth. COURTESY OF ERIK HANDERSON

The population of a seldom-seen snake native to the Tucson area is thin enough to make it an endangered species, but it won't be protected as one - at least for now.

The Tucson shovel-nosed snake - whose population has dwindled because of agriculture and urban sprawl - has been designated by the U.S. Fish and Wildlife Service as a species that "warrants" protection under the Endangered Species Act, but it will not be protected because there are other species of higher priority, an agency release said.

The petition to designate the snake as endangered - submitted by the Center for Biological Diversity - will be deferred while the service works on proposals for other species that are at greater risk. It will then be reviewed annually until it is given protection or officials find that it is not warranted based on new information, the release said.

"Its a typical thing they do for something that isn't high profile. The threats facing this subspecies are so immediate that they need to get on the stick and get this done," said Phil Rosen, a research scientist at the UA School of Natural Resources and the Environment.

Shovel-nosed snakes have adapted to "swim" through sandy soils and in part because of this adaptation, they are dependent on specific habitats found on the level terrain of valley floors.

Urbanization in places like Tucson, Phoenix and Casa Grande, along with agriculture growth, has made the snake increasingly rare, Rosen said. The nearest population is around Picacho Peak.

"In Avra Valley the population distribution has contracted in the last 20 years," Rosen said. "It was once abundant, but as far as we can tell now they're completely gone from there."

The center argues that the Fish and Wildlife Service has the resources to protect the more than 250 animals listed in the "warranted, but precluded" category and is in violation of the Endangered Species Act by not making quick progress on designating other species not on the list, Tierra Curry, a biologist at the Center for Biological Diversity, said this week.

The lack of protection gives the snake a bleak chance at survival, Curry said.

"Its like a purgatory where species go extinct while waiting for protection," Curry said. "All the science is there, but the services aren't going in to protect the habitat."