Center for Biological Diversity and Southern Utah Wilderness
the U. S. Fish and Wildlife Service in May 2002 to list a
rare southwestern amphibian, the relict leopard frog, as an
endangered species under the Endangered Species Act. The Fish and Wildlife Service designated the relict leopard frog as a “Candidate” species for federal listing in July 2002, and is currently drafting a Conservation Agreement and Strategy with state and federal wildlife agencies. The Center filed a lawsuit in 2005 against the Service for failing to make “expeditious progress” in protecting the relict leopard frog and 285 other known imperiled species on the candidate waiting list.
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.
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.
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.
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
National Park Service
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.