Sierra Nevada Yellow-legged Frog
Photo Credit: Rick Kuyper/USFWS
Basic Species Information
Endangered. This species is in danger of extinction throughout all or a significant portion of its range.
The Sierra Nevada yellow-legged frog is a medium-size amphibian, measuring about 1.5 to 3.25 inches on average. Females tend to be slightly larger than males.
Adult frogs have a mix of brown and yellow coloring on their upper (dorsal) body, but can also be grey, red, or greenish-brown, usually with dark spots or splotches, called cryptic coloration. These spots can look like lichen or moss and make the frog appear camouflaged. The belly and underside of their back legs, and sometimes the front legs, are yellow or light-orange. This gives the frog part of its common name—"yellow-legged."
If disturbed or threatened, Sierra Nevada yellow-legged frogs can produce a distinctive mink- or garlic-like odor to ward off predators and other animals. Although these frogs do not have vocal sacks, they can vocalize in or out of water, making what has been described as a flat clicking sound.
The Sierra Nevada yellow-legged frog is very similar to the mountain yellow-legged frog in that they look similar and are found in very similar habitats, but are a genetically different species. One physical difference between them is that, on average, the Sierra Nevada yellow-legged frog has shorter legs. At one time, both frogs were thought to be the same species—the mountain yellow-legged frog—until biologists determined that they were indeed different species.
This species eats a variety of terrestrial and aquatic invertebrates and tadpoles. It 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. They also creep up a little then strike—using their large sticky tongue to catch the prey and bring it into the mouth.
Typical habitat includes lakes, ponds, marshes, meadows, and streams at high elevations— typically ranging from about 4,500 to 12,000 feet, but can occur as low as about 3,500 feet in the northern portions of their range. Sierra Nevada yellow-legged frogs are highly aquatic and adults can be found sitting on rocks along the shoreline, where there was little or no vegetation. They are rarely found more than 3.3 feet from water.
This species tends to spend the winter at the bottom of frozen lakes, emerging shortly after snow melts. In years of heavy snow, they may only be active for about 3 months.
Reproduction is aquatic. Mature adults come into breeding condition and the males call to advertise their fitness to competing males and to females. Fertilization is external, with the male grasping the back of the female and releasing sperm as the female lays her eggs.
A cluster of 100 to 350 eggs 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.
If a body of water used for breeding dries up for just one season, three to four generations of tadpoles will be destroyed.
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.
These frogs occupy the western Sierra Nevada north of the Monarch Divide (in Fresno County) and the eastern slope of the Sierra Nevada (east of the crest) from Inyo County, through Mono County (including the Glass Mountains), to areas north of Lake Tahoe.
Although the area where the frog is found is close to what it had been historically, there are far fewer frogs found within this area now.
Most of these frogs are now found on National Forest and National Park lands.
There has been a range-wide reduction in abundance and geographic extent of surviving populations of frogs following decades of fish stocking, habitat fragmentation, and most recently a disease epidemic. Surviving populations are smaller and more isolated, and breeding in disease-infested populations is highly reduced from historic norms. Studies show that populations of Sierra Nevada yellow-legged frog have declined by almost 70 percent.
WHAT YOU CAN DO
Wherever you live in California, there are zoos and nature centers where you can see and learn about frogs.
Need more specifics? Download the Sierra Nevada yellow-legged frog scientific species account.