These are four videos of three different male frogs calling during an early summer afternoon in Alpine County. Running water, birds, insects, and an occasional Pacific Treefrog are heard in the background.
Several pairs of male and female frogs in amplexus are seen in this video with attempts by other males to steal the females. They are successfully fought off by the amplexing males, usually by a strong kick, but sometimes a long wrestling match ensues.
Several groups of male frogs are seen during the breeding season chasing and amplexing each other. You can hear release calls in the first few scenes. This behavior continued for hours, so it did not appear that they were mistaking each other for females they could breed with, but that it was some kind of territorial behavior between males. Or they could have been practicing their pouncing skills for when they encountered females in the future. (This is a long video which might take some time to download.)
Two males are seen during the breeding season chasing and amplexing each other until one leaves and the other begins calling.
This is a long (2 minute) version of a frog calling in the afternoon Alpine County.
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 gro 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 in or very close to water, typically within a couple of meters (two or three jumps away from water.)
Rarely occurs where predatory fishes have been introduced.
Adults and tadpoles often spend the winter at the bottom of frozen lakes. Adults may die under ice in winter due to low oxygen levels. Tadpoles are more tolerant of low oxygen levels.
Emerges shortly after snow melts.
In years of heavy snow and a long period of freezing temperatures, may only be active for about 3 months.
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, so the call has very little volume.
Diet and Feeding
Eats a variety of terrestrial and aquatic invertebrates and tadpoles.
May also consume dead frogs and its own eggs.
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.
The reproductive cycle is similar to that of most North American Frogs and Toads. Mature adults come into breeding condition and the males call to advertise their fitness to competing males and to females. Males and females pair up in amplexus in the water where the female lays her eggs as the male fertilizes them externally. The eggs hatch into tadpoles which feed in the water and eventually grow four legs, lose their tails and emerge onto land where they disperse into the surrounding territory.
Mating and egg-laying occurs in water shortly after the snows have melted and adults have emerged from hibernation, which can be any time from May - August.
Adults tend to live around the breeding pond, so most do not need to travel to the breeding site.
A cluster of 100 - 350 eggs (average 233) is laid in shallow water and is left unattached in still waters, but may be attached to vegetation in flowing water.
Egg-laying sites must be connected to permanent lakes or ponds that do not freeze to the bottom in winter, because the tadpoles must live in the water over winter.
Tadpoles and Young
Tadpoles overwinter, possibly taking as many as 3 or 4 summers before they transform.
Inhabits lakes, ponds, meadow streams, isolated pools, and sunny riverbanks in the Sierra Nevada Mountains.
Usually found in or very close to water, typically within a couple of meters (two or three jumps away from water.)
Highly adaptable in regards to what perching conditions (i.e., slope, canopy, cover, substrate) are available.
Once thought to only inhabit high elevation fishless lakes, recent research (2019) has shown that this species readily occupies streams, both perennial and intermittent, as well. Frogs will utilize slow pockets of water in fast-flowing streams.
"Seems to prefer sloping banks with rocks or vegetation to water's edge." (Stebbins 2003)
Waters that do not freeze to the bottom and which do not dry up completely are required.
(If a body of water used for breeding dries up for just one season, 3 - 4 generations of tadpoles will be destroyed.)
Historically, Rana sierrae ranged "...from the Diamond Mountains north-east of the Sierra Nevada in Plumas County, California, south through the Sierra Nevada to the type locality, the southern-most locality (Inyo County). In the extreme north-west region of the Sierra Nevada, several populations occur just north of the Feather River, and to the east, there was a population on Mt Rose, north-east of Lake Tahoe in Washoe County, Nevada, but it is now extinct. West of the Sierra Nevada crest, the southern part of the R. sierrae range is bordered by ridges that divide the Middle and South Fork of the Kings River, ranging from Mather Pass to the Monarch Divide. East of the Sierra Nevada crest, R. sierrae occurs in the Glass Mountains just south of Mono Lake (Mono County) and along the east slope of the Sierra Nevada south to the type locality at Matlock Lake (Inyo County)." (Vredenburg, et al, 2007.)
From 984 ft. to 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.
Endangered and absent from a significant part of its historic range. The decline has been attributed to many factors, including introduced non-native trout, airborne pollution, insufficient snowmelt to fill breeding ponds brought about by climate change, cattle grazing, ozone depletion, pollution from mining, public dumping, and chytrid fungus. Fish introductions have stopped in some areas, such as National Parkland, they continue in others. But while it has been documented that introduced trout are substantially reducing the numbers of the frogs, frogs have also disappeared in one watershed where no trout have been introduced, which suggests multiple causes for their decline.
Researchers have discovered protective bacteria on the skin of wild frogs that have survived the chytrid fungus which they have recreated in the lab and used to kill the fungus. Experiments by Vance Vredenburg with wild frogs have shown some success - a 2011 survey found that the only surviving frogs at one location were those that had been treated with the bacteria in 2010.
Proposed for Federally Endangered listing 4/25/13.
Federally Protected under the Endangered Species Act 4/25/14.
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
Sierra Nevada Yellow-legged Frog
Rana muscosa: 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.
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.
Special Animals List Notes:
Sierra Nevada yellow-legged frog
1) Formerly Rana muscosa. 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.
2) Rana sierrae is a federally proposed endangered species (Apr 2013).
3) The USFWS published a final rule on April 29, 2014, to list the Sierra Nevada yellow-legged frog as Endangered.This rule becomes effective June 30, 2014.