California Reptiles & Amphibians

Rana muscosa - Southern Mountain Yellow-legged Frog

Click on a picture for a larger view

Original Range in California: Red

Adult, San Gabriel Mountains, Los Angeles County

Juvenile, San Gabriel Mountains, Los Angeles County

Adult, San Gabriel Mountains, Los Angeles County

Transforming tadpole underwater, San Gabriel Mountains, Los Angeles County

Juvenile, San Gabriel Mountains, Los Angeles County

Juveniles, San Gabriel Mountains, Los Angeles County

Adult, San Gabriel Mountains, Los Angeles County

Juvenile, San Gabriel Mountains, Los Angeles County

Adult, San Gabriel Mountains, Los Angeles County

Adult, underwater, San Gabriel Mountains, Los Angeles County

Adult, San Gabriel Mountains, Los Angeles County

Adult, Angeles National Forest, San Gabriel Mountains, Los Angeles County
© 2003 William Flaxington

Adult, Mt. San Jacinto, Riverside County@ 2005 Brian Hubbs

Adult frogs, part of the captive breeding program at the San Diego Zoo's Center for Conservation
and Research for Endangered Species, courtesy of Jeffrey M. Lemm. Photos © Gary Nafis

Juvenile, raised in captivity, part of the captive breeding program at the San Diego Zoo's Center for Conservation and Research for Endangered Species, courtesy of Jeffrey M. Lemm. © Gary Nafis

Pair of amplexing adults, part of the captive breeding program at the San Diego Zoo's Center for Conservation and Research for Endangered Species, courtesy of Jeffrey M. Lemm. © Gary Nafis

Amplexing adults, part of the captive breeding program at the San Diego Zoo's Center for Conservation and Research for Endangered Species.
© Jeffrey M. Lemm

Eggs, close-up, part of the captive breeding program at the San Diego Zoo's Center for Conservation and Research for Endangered Species.
© Jeffrey M. Lemm

Habitat, 5,600 ft., Mt. San Jacinto, Riverside County

Habitat, 5,300 ft., San Gabriel Mountains, Los Angeles County

Habitat, 5,100 ft., San Gabriel Mountains, Los Angeles County

Habitat

Habitat, 5,100 ft., San Gabriel Mountains, Los Angeles County

Habitat, 5,200 ft., San Gabriel Mountains, Los Angeles County

Habitat, 5,000 ft., San Gabriel Mountains, Los Angeles County

Habitat, San Gabriel Mountains, Los Angeles County
© William Flaxington

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

Short Videos

Juvenile and adult Southern Mountain Yellow-legged Frogs do what frogs do on a summer day in a creek in the San Gabriel Mountains.

Description

Size

Moderate in size. Adults are 1.5 - 3.5 in. long from snout to vent (4.0 - 8.9 cm).

Appearance

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. Indistinct dorsolateral folds. No dark face mask. Smells like garlic when handled. Differs from Rana sierrae by having relatively longer legs and a significantly different mating call.

Voice

The call is 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. (You can listen to the similar call of the related Sierra Nevada Yellow-legged Frog here, or on the Carlos Davidson CD.)

Behavior

A mountain frog. Chiefly diurnal. Emerges shortly after snow melts. Usually found close to water. Rarely occurs where predatory fishes have been introduced.

Diet

Eats a variety of terrestrial and aquatic invertebrates and tadpoles. Typical of most frogs, the prey is located by vision, then a large sticky tongue is used to catch the prey and bring it into the mouth to eat.

Reproduction

Mating and egg-laying occurs after high creek waters have subsided, from March - July in the southern California populations. In the southern Sierra Nevada populations, breeding may occur later after the snows melt from May to July. Fertilization is external. 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 in the Sierras may overwinter, possibly taking as many as 3 or 4 summers before they transform.

Range

Formerly 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.)

Habitat

Inhabits lakes, meadow streams, isolated pools, sunny riverbanks in the Sierra Nevada. In southern California, inhabits rocky streams. Open stream and lake edges with a gentle slope up to a depth of 5-8 cm. seem to be preferred. From 984 ft. - over 12,000 ft. elevation (370 - 3,660 m.)

Taxonomic Notes

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.

Conservation Issues (Conservation Status)

Endangered in Southern California and the southern Sierra Nevada Mountains, where it is absent from most of its historic range. The frogs are considered extinct on Breckenridge Mountain and Mt. Palomar. Only a few creeks have been found with frogs in the San Gabriel, San Bernrdino, and San Jacinto mountains. The decline has been attributed to many factors, including bullfrogs, 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.

Taxonomy
Family	Ranidae	True Frogs
Genus	Rana	True Frogs
Species	muscosa	Southern Mountain Yellow-legged Frog
Original Description
Camp, 1917 - Univ. California Publ. Zool., Vol. 17, No. 9, p. 118 from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
Meaning of the Scientific Name
Rana - Frog - "Rana" probably mimics how the Romans heard their call. muscosa - Latin - mossy, full of moss- referring to the lichen-like dark dorsal patches from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
Alternate Names
Formerly Rana muscosa - Mountain Yellow-legged Frog (which included the species Rana sierrae.) Rana muscosa - Sierra Madre Yellow-legged Frog
Related or Similar California Frogs
Rana aurora Rana boylii Rana cascadae Rana catesbeiana Rana draytonii Rana pipiens Rana pretiosa Rana sierrae Rana yavapaiensis
More Information and References
Natureserve Explorer California Dept. of Fish and Game AmphibiaWeb Center for Biological Diversity Dr. Roland Knapp's site Rescuing a Dying Breed - Saving the Southern California Mountain Yellow-legged Frog The Mountain Yellow-legged Frog - Can They Be Saved? Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003. Behler, John L., & F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992. 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. Wright, Anna. 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. Vredenburg, V. T., R. Bingham, R. Knapp, J. A. T. Morgan, C. Moritz & D. Wake (2007. Journal of Zoology 271: 361–374)

Conservation Status
The following status listings come from the Special Animals List which is published several times each year by the California Department of Fish and Game.
Organization	Status Listing
U.S. Endangered Species Act (ESA)	FE	Endangered
California Endangered Species Act (CESA)	None
California Department of Fish and Game	DFG:SSC	California Species of Special Concern
Bureau of Land Management	None
USDA Forest Service	USFS:S	Sensitive
Natureserve Global Conservation Status Ranks	G1 S1	Critically Imperiled
World Conservation Union - IUCN Red List	IUCN:EN	Endangered

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