TUCSON (CN) - Livestock grazing in Arizona National Forests is trampling two threatened snakes and their aquatic habitat out of existence, environmentalists claim in a pre-suit notice.
The Center for Biological Diversity told the Forest Service this week that it's preparing an action to challenge 170 grazing permits in the Apache-Sitgreaves, Coconino, Coronado, Prescott and Tonto National Forests.
"Historical or unmanaged grazing" in the forests already HAS destroyed much of the riparian habitat of the narrow-headed garter snake and the northern Mexican garter snake, according to Jay Lininger, the Center's senior scientist.
Lininger on Tuesday sent the Forest Service a notice of intent to sue under the Endangered Species Act. The Center for Biological Diversity now has 60 days to file a lawsuit.
Both snakes gained threatened status in July. The listing decision stated that 24 of 29 known populations of northern Mexican garter snakes, and 31 of 41 known populations of narrow headed garter snakes, "are likely not viable and may exist at low population densities that could be threatened with extirpation or may already be extirpated."
In late 2013 the U.S. Fish and Wildlife Service moved to protect some 421,000 acres in central and southern Arizona, including more than 1,000 "stream miles," as critical habitat for the snakes.
While that designation is expected to take effect sometime in 2015, the Center for Biological Diversity said this week that the "threatened snakes cannot afford further delay of biological reviews required to ensure their protection from livestock grazing."
In the meantime, the Center claims, the Forest Service failed to consult with federal biologists on how continued grazing in Arizona's forests will affect the two snakes. The notice says the group will also challenge permits in New Mexico's Gila National Forest.
"Northern Mexican and narrow headed garter snakes suffer both direct mortality and loss of essential habitat and prey base due to livestock grazing in riparian areas," Lininger wrote.
"Specifically, results indicated that snake abundance and biomass were significantly higher in ungrazed habitat, with a five-fold difference in number of snakes captured."
Fish and Wildlife does not agree that livestock grazing is hurting the Northern Mexican garter snake and narrow-headed garter snake populations in Arizona.
In announcing the proposed habitat designation in July 2013, Arizona Field Supervisor Steve Spangle said that "livestock operations do not pose a significant threat to either garter snake."
Spangle blamed "interactions with nonnative bullfrogs, crayfish, and nonnative spiny-rayed fish," for the snakes' decline.
"Human activities that diminish surface water or degrade streamside (riparian) vegetation are also significant threats, but particularly where they co-occur in the presence of nonnative species," he said. "Efforts to control nonnative predators and restore native aquatic and riparian communities could significantly benefit both garter snakes and a suite of other imperiled native fish and amphibian species throughout their range."
The northern Mexican garter snake, which can grow to 44 inches, typically lives along streams, and can also be found in stock tanks. Fish and Wildlife's habitat proposal expressly exempts stock tanks and "impoundments maintained by cattlemen as livestock watering holes."
Federal biologists believe that the northern Mexican garter snake, once a wide-ranging Southwestern species, is now limited to central Arizona's Verde River drainage, the San Rafael Valley and the Bill Williams River.
The narrow-headed garter snake grows up to 34 inches long and feeds on trout and other native fish in Arizona's high-country streams along the Mogollon Rim.