TUCSON, Ariz. - The U.S. Fish and Wildlife Service on Wednesday proposed listing the Chiricahua leopard frog as threatened under the Endangered Species Act.
The dark-spotted green frog once was common in southeastern Arizona and southwestern New Mexico, but now is found at only 79 locations, many of them isolated stock tanks.
The agency cited threats to the species from non-native predators such as fish, bullfrogs and crayfish, loss and fragmentation of habitat, a fungal disease and environmental contamination.
''The Chiricahua leopard frog is a unique part of the Southwest's natural heritage and it is disturbing to see its decline and even disappearance throughout much of its range,'' said Fish and Wildlife regional director Nancy Kaufman.
The frog has been a candidate for listing since 1991, and two years ago the Center for Biological Diversity petitioned for its listing. Last year, it sued the Fish and Wildlife Service for failure to act on its petition to list the frog and a native fish, the Gila chub, as threatened.
A federal judge ruled in favor of the service and the center's appeal is pending before an appeals court.
Because many of the remaining frog populations are found in stock tanks or livestock watering holes, Fish and Wildlife proposed a special rule in its proposed listing. It would allow ranchers to operate and maintain those stock tanks on private or tribal land without permits normally required to authorize the incidental harassing, harming or killing of a leopard frog.
Noah Greenwald, a spokesman for the Center for Biological Diversity, which often challenges federal agencies on environmental issues, said that according to Fish and Wildlife's proposed rule, ''These habitats are highly dynamic and may be marginal habitats for leopard frogs... Only small populations are supported by such tanks.''
Greenwald said the tanks ''in no way substitute for natural stream habitats, which have largely been destroyed by livestock grazing.'' He said such grazing must be curtailed in riparian areas for the species to recover.
The frog, typically from 2 to 4 inches long, also is found in mountain streams and ponds.
The frog once was known to inhabit 212 sites in Arizona, 170 in New Mexico and another dozen or so in Mexico. But since 1995, it has been found at only 52 Arizona sites and 27 in New Mexico - with 47 of those locations on U.S. Forest Service lands, mostly in the Coronado National Forest.
The Fish and Wildlife Service said a number or individuals and organizations are involved in trying to conserve the frog, from environmental groups and state agencies to ranchers and high school students.
