Mountain Yellow-legged Frog (Northern Distinct Population Segment [DPS])

Rana muscosa

Picture of Mt Yellow-Legged Frog
Photo Credit: Ricky Kuyper/USFWS

Mountain Yellow-legged Frog (Northern Distinct Population Segment [DPS])

Basic Species Information

STATUS

Endangered. This species is in danger of extinction throughout all or a significant portion of its range.

DESCRIPTION

The mountain yellow-legged frog is medium size, measuring about 3 to 8 cm (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 body, but can also be grey, red, or greenish-brown, usually with dark spots or splotches. These spots can look like lichen or moss, to give the frog a camouflaged look. The belly and underside of the back legs, and sometimes all the way up to the front legs, are yellow or light-orange. This gives the frog its name of "yellow-legged."

If disturbed or threatened, these frogs produce a distinctive mink-or garlic-like odor to ward off predators and other animals.

Although these frogs do not havevocal sacks, they can vocalize in or out of water, making what has been described as a flat "clicking" sound.

The tadpoles reach about 7 cm (2.8 inches) in length and generally are mottled brown on the dorsal side with a faintly yellow underside. Tadpoles often require 2 to 4 years to reach metamorphosis, depending on local climate conditions and site-specific variables. The time required to reach reproductive maturity in mountain yellow-legged frogs is thought to vary between 3 and 4 years after metamorphosis.

FOOD SOURCES

This species 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.

HABITAT

Mountain 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 and rarely found more than a meter (3.3 feet) from water.

These species historically inhabited lakes, ponds, marshes, meadows, and streams at elevations typically ranging from about 1,371 to 36,957 m (about 4,500 to 12,000 feet), but can occur as low as 1,067 m (about 3,500 feet) in the northern portions of their range.

HIBERNATION

This species emerges shortly after snow melts. In years of heavy snow, the frog may only be active for about 3 months.

MATING

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.

It takes 5 to 8 years for these frogs to start reproducing.

Mountain yellow-legged frogs deposit their eggs in globular clumps, which are often somewhat flattened and roughly 1 to 2 inches in diameter.

Spawn size varies from 15 to 350 eggs per mass and eggs hatch in 18 to 21 days with water temperatures from 41 to 56 degrees Fahrenheit.

RANGE

The northern DPS of the mountain yellow-legged frog occurs only in the western Sierra Nevada and extends from south of the Monarch Divide in Fresno County through portions of the Kern River drainage.

Most of these frogs are now found on National Forest and National Park lands.

THREATS

Studies show that populations of the northern DPS of mountain yellow-legged frog have declined by over 80 percent.

Threats include habitat degradation and fragmentation, predation and disease, climate change, and the interaction of these various stressors impacting small remnant populations.

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.

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 Mountain Yellow-legged Frog (northern DPS) scientific species account.