Mountain Yellow-legged Frog (Rana muscosa) Fact Sheet: Population & Conservation Status

IUCN Status

• Endangered  (2008 assessment) (Hammerson G. 2008)

CITES Status

• Not listed (as of May 2019) (UNEP 2019)

United States Endangered Species Act

• Endangered

 History of Conservation Efforts

• Identification of two distinct populations: northern and southern California
  • 2002: Given Endangered Species Status by USFWS
  • 2006: Designation of Critical Habitat by USFWS; 8,283 acres in portions of Los Angeles, Riverside, and San Bernardino counties
  • 1996-2004: Listed as Vulnerable by IUCN
  • 2006: Listed as Critically Endangered by IUCN
  • 2008: Listed as Endangered by IUCN

By 2003, fewer than 200 individuals remained in the wild

• Survey of 150 historical distribution sites (Backlin 2013)
  • Nine small populations were detected
  • Abundance estimates were small (1–55 adults per population).
  • Data indicated most of the remaining populations had fewer than 10 pairs of adults.
• Reintroductions of individuals bred in managed care supplementing reproduction in wild populations

SDZG Institute for Conservation Research

• Leading efforts to study the reproduction and natural history of this species, with ultimate goal of preventing its extinction
• Hatch eggs and raise young frogs in managed care
  • Release into the wild
• Working to improve husbandry and managed care breeding protocols
  • Simulate seasonal temperature changes (hibernation cues)
  • Simulate natural light cycles
  • Study nutritional requirements
• Use assisted reproduction techniques (e.g., hormone therapies and in vitro fertilization)
• Partnerships with the California Department of Fish and Wildlife, U.S. Forest Service, U.S. Fish and Wildlife Service, U.S. Department of Agriculture, U.S. Geological Survey, and Los Angeles Zoo
• Preserving genes in The Frozen Zoo®
• Studying embryo and tadpole development
• See Managed Care

(Hammerson 2008)

Diseases

• Chytrid fungus
• Red-leg disease/syndrome

Predation

• Predation on tadpoles by non-native fish
• specially introduced trout

Environmental effects

• Drought
• Fire (San Diego Zoo Global Press Releases)
• Habitat saturated in ash and debris
• Loss of genetic vigor due to population isolation and inbreeding
• Air and water contamination
• Agricultural chemicals/pesticides
• Low pH and elevated aluminum concentrations
• Mining
• Human disturbance of wildlife areas
• Threats described by IUCN (International Union for Conservation of Nature)

Learn how San Diego Zoo Global researchers raise endangered mountain yellow-legged froglets for reintroduction into the wild.

© San Diego Zoo Global. All rights reserved.

ICR Senior Research Coordinator, Jeff Lemm, checks a clutch of Mountain Yellow-Legged Frog eggs.

The San Diego Zoo Institute for Conservation Research (ICR) has been breeding, raising and reintroducing frogs into historical native habitat since 2010.

Image credit: Ken Bohn, © San Diego Zoo Global. All rights reserved.

 

Release into Fuller Mill Creek.

Image credit: Ken Bohn, © San Diego Zoo Global. All rights reserved.

USFWS (2002)
USFWS (2006)
IUCN (2004)
IUCN (2006)
IUCN (2008)
Backlin (2013)
Fellers et al. (2001)
Vredenburg et al. (2008)