National Forest Service signs detailing the attempt to protect a small struggling population of Southern
California Mountain Yellow-legged Frogs on Mt. San Jacinto, Riverside County
Some of the few last remaining juvenile and adult Southern Mountain Yellow-legged Frogs in a small creek on a sunny summer day in the San Gabriel Mountains.
Adults are moderate in size, 2 - 3 inches long from snout to vent (5 - 7.6 cm). (Stebbins & McGinnis, 2012)
A medium-sized frog with a slim waist, long legs, smooth skin and webbing on the hind feet.
Ridges on the sides (dorsolateral folds) are not distinct.
Differs from Rana muscosa by having relatively shorter legs and a significantly different mating call.
When it is extended forward, the heel of the hind foot of Rana sierrae usually does not reach the nostril. The heel of Rana muscosa does reach the nostril.
Color and Pattern
Variable in color - olive, yellowish or brown above, with varying amounts of black or brown markings.
Pale orange to yellow below and underneath the hind legs.
No dark face mask is present.
Tadpoles grow up to 2 inches in length (5 cm.)
Coloring is brown with a tint of gold and dark spots.
A mountain frog of high elevations.
Usually found close to water, typically within a couple of meters.
Rarely occurs where predatory fishes have been introduced.
Probably spends the winter at the bottom of frozen lakes.
Emerges shortly after snow melts.
In years of heavy snow, may only be active for about 3 months.
Smells like garlic when handled.
This frog makeis a short and rasping call often accellerated and rising at the end, sometimes preceeded by calls that don't rise at the end. Calls primarily underwater during the day, but may also call at night. This frog has no vocal sacs so the sound produced is fairly quiet. (You can listen to it online at the Western Soundscape Archive, and on the Lang Elliot and the Carlos Davidson CDs listed below in References.)
Diet and Feeding
Eats a variety of terrestrial and aquatic invertebrates, including beetles, ants, bees, wasps, flies, and dragonflies.
Tadpoles may also be consumed.
Frogs tend to sit and wait until they see prey come within range, then they strike, or creep up a little then strike, using their large sticky tongue to catch the prey and bring it into the mouth.
Reproduction is aquatic.
Fertilization is external, with the male grasping the back of the female and releasing sperm as the female lays her eggs.
Mating and egg-laying occurs after high creek waters have subsided, from March - May in the southern California populations.
In the southern Sierra Nevada populations, breeding may occur later after the snows melt from May to July.
A cluster of eggs is laid in shallow water and is left unattached in still waters, but may be attached to vegetation in streams.
Tadpoles and Young
There is no information on the larval stage of Southern California populations, but it's possible they could transform their first year.
Tadpoles in the Sierra Nevada may overwinter, possibly taking as many as 3 or 4 summers before they transform.
Inhabits lakes, ponds, meadow streams, isolated pools, sunny riverbanks in the southern Sierra Nevada Mountians.
In the mountains of southern California, inhabits rocky streams in narrow canyons and in the chaparral belt.
"...frequents streams that range from rocky, steep drainages to those with a gentle gradient, marshy margins, and sod banks. Large clear pools up to three feet deep are especially favored." (Stebbins & McGinnis 2012)
No longer found in much of its former habitat. Historically Rana muscosa ranged "...from Palomar Mountain in San Diego County through the San Jacinto, San Bernardino and San Gabriel Mountains of Riverside, San
Bernardino and Los Angeles counties in southern California. These formed four isolated clusters of montane populations. In addition, the species occurred as an isolated cluster of populations on Breckenridge Mountain, south of the Kern River in Kern County, and in the Sierra Nevada in Tulare, Inyo and Fresno counties, extending north to Mather Pass. The distribution of R. muscosa in the Sierra Nevada is bordered by the crest of Sierra Nevada. No populations occur east of the crest. The mountain ridges that separate the headwaters of the South Fork Kings River from the Middle Fork Kings River, from Mather Pass to the Monarch Divide, form the northern border of the range. ... Rana muscosa is extinct on Palomar and Breckenridge mountains."
(Vredenburg, et al, 2007.)
From 984 ft. - over 12,000 ft. elevation (370 - 3,660 m.)
Notes on Taxonomy
According to a February, 2008 petition by the Center for Biological Diversity and Pacific Rivers Council to list the Sierra Nevada Mountain Yellow-legged Frog as an Endangered Species, "The mountain yellow-legged frog in the Sierra Nevada is geographically, morphologically and genetically distinct from mountain yellow legged frogs in southern California. It is undisputedly a 'species' under the ESAOs listing criteria and warrants recognition as such."
Vredenburg, V. T., R. Bingham, R. Knapp, J. A. T. Morgan, C. Moritz & D. Wake (2007. Journal of Zoology 271: 361–374) have determined that this taxon consists of two species, which they name Rana muscosa - Sierra Madre Yellow-legged Frog, and Rana sierrae - Sierra Nevada Yellow-legged Frog. More from the CNAH.
In 2008, the Society for the Study of Amphibians and Reptiles recognized two species, Rana muscosa - Southern Mountain Yellow-legged Frog , and Rana sierrae - Sierra Nevada Yellow-legged Frog.
Alternate and Previous Names (Synonyms)
Rana muscosa - Mountain Yellow-legged Frog (Stebbins 1966, 1985, 2003) Rana boylii muscosa (Stebbins 1954)
Rana boylii muscosa - Sierra Madre Yellow-legged Frog (Southern Yellow-legged Frog) (Wright & Wright 1949)
Rana boylii muscosa - Sierra Madre Yellow-legged Frog (Storer 1925) Rana boylii muscosa - Sierra Madre Yellow-legged Frog (Grinnell and Camp 1917)
Endangered in Southern California and the southern Sierra Nevada Mountains, where it is absent from most of its historic range. Once thought to be extinct in the San Bernardino Mountains until a small population was discovered. Considered extinct on Breckenridge Mountain and Mt. Palomar. Only a few creeks have been found with frogs in the San Gabriel, San Bernardino, and San Jacinto mountains. This decline has been attributed to many factors, including bullfrogs, introduced non-native trout, airborne pollution, cattle grazing, ozone depletion, mining pollution, off road vehicle disturbance, public dumping, chytrid fungus, fires, and excessive flooding.
In June, 2009, biologists from the U.S. Geological Survey and scientists from the San Diego Natural History Museum retraced a 1908 expedition through the San Jacinto Wilderness near Idyllwild and re-discovered a population of frogs in two creeks 2.5 miles apart.
The San Diego Zoo, along with the California Dept. of Fish and Game, the U.S. Fish and Wildlife Service, the U. S. Forest Service, and the U.S. Geological Survey, has developed a Mountain Yellow-legged Frog Recovery Program, a captive breeding and translocation plan for the only remaining frogs known from the San Bernardino Mountains. In August of 2006, 75 tadpoles were removed from a drying creek bed in the San Bernardino Mountains and transferred to the program. They began planting eggs into the wild in April 2010.
In August, 2016, the U.S. Fish and Wildlife Service announced the designation of 1.8 million acres of protected critical habitat in the Sierra Nevada mountains for Rana sierrae, the Sierra Nevada Yellow-legged Frog, the northern population of Rana muscosa, the Southern Mountain Yellow-legged Frog, and Anaxyrus canorus, the Yosemite Toad. BiologicalDiversity.org
Southern Mountain Yellow-legged Frog
Camp, 1917 - Univ. California Publ. Zool., Vol. 17, No. 9, p. 118
Stebbins, Robert C., and McGinnis, Samuel M. Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012.
Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972.
Flaxington, William C. Amphibians and Reptiles of California: Field Observations, Distribution, and Natural History. Fieldnotes Press, Anaheim, California, 2021.
Samuel M. McGinnis and Robert C. Stebbins. Peterson Field Guide to Western Reptiles & Amphibians. 4th Edition. Houghton Mifflin Harcourt Publishing Company, 2018.
Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.
Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.
Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998.
Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Amphibians of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009.
Elliott, Lang, Carl Gerhardt, and Carlos Davidson. Frogs and Toads of North America, a Comprehensive Guide to their Identification, Behavior, and Calls. Houghton Mifflin Harcourt, 2009.
Lannoo, Michael (Editor). Amphibian Declines: The Conservation Status of United States Species. University of California Press, June 2005.
Storer, Tracy I. A Synopsis of the Amphibia of California. University of California Press Berkeley, California 1925.
Wright, Albert Hazen and Anna Wright. Handbook of Frogs and Toads of the United States and Canada. Cornell University Press, 1949.
Basey, Harold E. Discovering Sierra Reptiles and Amphibians. Yosemite Association and Sequoia Natural History Association, 1976, 1991.
Davidson, Carlos. Booklet to the CD Frog and Toad Calls of the Pacific Coast - Vanishing Voices. Cornell Laboratory of Ornithology, 1995.
Lang Elliott, Carl Gerhardt, and Carlos Davidson - The Frogs and Toads of North America - Houghton Mifflin Harcourt. 2009.
Vredenburg, V. T., R. Bingham, R. Knapp, J. A. T. Morgan, C. Moritz & D. Wake (2007. Journal of Zoology 271: 361–374)
Joseph Grinnell and Charles Lewis Camp. A Distributional List of the Amphibians and Reptiles of California. University of California Publications in Zoology Vol. 17, No. 10, pp. 127-208. July 11, 1917.
The following conservation status listings for this animal are taken from the October 2021 California "Special Animals List" and the October 2021 "State and Federally Listed Endangered and Threatened Animals of California" list, both of which are produced by multiple agencies and available here: https://www.wildlife.ca.gov/Data/CNDDB/Plants-and-Animals. You can check the link to see if there are more recent lists.
If no status is listed here, the animal is not included on either list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status you can go to the NatureServe and IUCN websites to check their rankings.
Though the scientific name Rana muscosa is not disputed, the State of California uses the common name Southern Mountain Yellow-legged Frog whereas the USFWS listing refers to two distinct population segments.
Mountain Yellow-legged Frog [Southern California DPS]
San Gabriel, San Jacinto, and San Bernardino Mountains only.
Mountain Yellow-legged Frog [Northern California DPS] North of the Tehachapi Mountains from the Monarch Divide to portions of the Kern River drainage.
Special Animals List Notes:
1) Federal listing refers to populations in the San Gabriel, San Jacinto & San Bernardino Mountains (Southern California DPS).
2) Federal Proposed status refers to all populations that occur north of the Tehachapi Mountains in the Sierra Nevada (Northern California DPS). The USFWS published a final rule on April 29, 2014, to list the northern DPS of Rana mucosa as Endangered.This rule becomes effective June 30, 2014.
3) Rana muscosa has been split into Rana sierrae, the Sierra Nevada yellow-legged frog, found in the northern and central Sierra Nevada and Rana muscosa, the southern mountain yellow-legged frog, found in the southern Sierra Nevada and southern California.
NatureServe Global Ranking
Critically Imperiled—At very high risk of extinction due to extreme rarity (often 5 or fewer populations), very steep declines, or other factors. Imperiled—At high risk of extinction due to very restricted range, very few populations (often 20 or fewer), steep declines, or other factors.
NatureServe State Ranking
Critically imperiled in the state because of extreme rarity (often 5 or fewer populations) orbecause of factor(s) such as very steep declines making it especially vulnerable to extirpation from the state.
U.S. Endangered Species Act (ESA)
Endangered: Southern California DPS 8/1/02
Endangered: Northern California DPS 6/30/14