Center for Biological Diversity

Protecting endangered species and wild places through
science, policy, education, and environmental law.



Contact: Jeff Miller (510) 841-0812, Center for Biological Diversity
Steve Bloch (801) 486-3161 ext.16, Southern Utah Wilderness Alliance
More Information: Relict Frog web site

Conservation groups formally petitioned today to list a rare southwestern amphibian as an endangered species under the Endangered Species Act. The Center for Biological Diversity ("CBD") and Southern Utah Wilderness Alliance ("SUWA") petitioned the U. S. Fish and Wildlife Service to add the relict leopard frog (Rana onca) to the growing list of endangered amphibians.

The relict leopard frog was one of the first North American amphibians thought to have become extinct. The last historical collections of the species were in the 1950s and a handful of relict leopard frog populations were only rediscovered in the early 1990s. This extremely endangered amphibian is now restricted to six springs in two separate localities within the Lake Mead National Recreation Area in Nevada. It is estimated that less than 1,100 adult relict leopard frogs remain, putting the species at severe risk of extinction.

"The relict leopard frog is a species on the brink," said Jeff Miller, spokesman for the CBD. "It is imperative that we protect the remaining springs where it occurs and that suitable habitat for reintroduction efforts is not further degraded by development and water projects."

"The relict leopard frog should serve as one of southern Utah's canaries in a coal mine," said SUWA attorney Steve Bloch. "The loss of the relict leopard frog and its critical habitat speaks directly to how water developments and urban sprawl have dramatically changed southern Utah's fragile environment," Bloch continued.

The species historically occurred in springs, seeps, and wetlands within the Virgin, Muddy, and Colorado River drainages, in Utah, Nevada, and Arizona. Populations of the extinct "Vegas Valley leopard frog," which once inhabited springs in the Las Vegas, Nevada area, were considered by many herpetologists to be the same species as the relict leopard frog. The species has been extirpated from 91% of its known historical localities.

Since relict leopard frogs were rediscovered in eight springs in the 1990s near Lake Mead and along the Virgin River, frogs have disappeared from two of these sites in the last decade. The species has been extirpated from Utah, Arizona, and from the Muddy River drainage in Nevada, and persists in only a tiny fraction of its known historical range.

Habitat changes due to water development, and agricultural and urban development impacts were responsible for eliminating much of the frog's original habitat. The damming of the Colorado River and the formation of Lake Mead Lake in 1935, and Lake Mojave in 1951 flooded relict leopard frog habitat, reduced connectivity between the remaining populations, and altered the hydrologic regime necessary to maintain relict leopard frog habitats.

The remaining relict leopard frog populations suffer from low genetic variation and are very vulnerable to extinction due to population fragmentation and the small size and isolation of their remaining habitat. The species is also threatened by potential water development along the Muddy and Virgin Rivers; predation and competition by introduced species such as bullfrogs, exotic fish, and crayfish; habitat alteration by invasive plants; the potential for contracting diseases that have hit other leopard frog species in the region; impacts from feral burros; recreational impacts by visitors to Lake Mead; and habitat alteration due to natural erosion and scouring.

The Center for Biological Diversity is a nonprofit environmental organization dedicated to the protection of native species and their habitats in the Western Hemisphere. The Center for Biological Diversity works to protect and restore natural ecosystems and imperiled species through science, education, policy, and environmental law. The Southern Utah Wilderness Alliance is a non-profit environmental membership organization dedicated to the sensible management of all public lands within the State of Utah, to the preservation and protection of plant and animal species, and to the preservation of Utah's remaining wild lands.


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