FWS Focus

Overview

Characteristics
Overview

The mountain yellow-legged frog is a medium-sized frog and includes two distinct groups - the southern distinct population segment, which was listed as endangered in 2002, and the northern distinct population segment, which was listed as endangered in 2013. The two populations are geographically separated by a 140-mile stretch of unsuitable habitat.

The biggest threats to the species are:

  • Habitat destruction due to dams and water diversions, recreation, grazing, road construction and timber harvesting
  • Impacts of climate change climate change
    Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

    Learn more about climate change
    , including wildfire and drought
  • Introduction of trout, bullfrogs and other non-native species that carry diseases and eat the frog

Scientific Name

Rana muscosa
Common Name
Mountain Yellow-legged Frog
Southern Mountain Yellow-legged Frog
FWS Category
Amphibians
Kingdom

Location in Taxonomic Tree

Genus

Identification Numbers

TSN:

Characteristics

Characteristic category

Life Cycle

Characteristics
Reproduction

Mountain yellow-legged frogs reach sexual maturity at 3 and 4 years of age. Adults emerge from overwintering sites immediately following snowmelt and move toward breeding sites. They will even move over ice to get there. The frogs breed in the shallows of ponds and lakes or in inlet streams. 

Mountain yellow-legged frogs deposit their eggs underwater in clusters, which they attach to rocks, gravel or vegetation. Eggs hatch between 16 to 21 days after fertilization.

Life Span

While the life span of mountain yellow-legged frogs is unknown, they are presumed to be long-lived amphibians.

Characteristic category

Food

Characteristics
Food

Adults feed on terrestrial and aquatic insects and other amphibians. Adults forage for prey at the bottoms of lakes, ponds, and streams, as well as in shallow waters and onshore. Tadpoles feed on algae.

Characteristic category

Behavior

Characteristics
Behavior

Mountain yellow-legged frogs maximize body temperatures during the day by basking in the sun, moving between water and land and concentrating in the warmer shallows along the shoreline. 

Mountain yellow-legged frogs return to the same overwintering and summer habitats each year. Both adults and tadpoles overwinter for up to nine months in the bottoms of lakes, ponds and in-stream pools that are at least 5.6 feet deep (1.7 meters); however, overwinter survival may be greater in lakes that are at least 8.2 feet (2.5 meters) deep. Rock crevices, holes and ledges near water offer protection to overwintering frogs when water bodies freeze over completely.
 

Characteristic category

Physical Characteristics

Characteristics
Size & Shape

The mountain yellow-legged frog is a medium-sized frog, with males are slightly smaller than females.

Measurements
Length: 1.5 to 3.75 in (40 to 95 mm)

Color & Pattern

Adult coloration is highly variable, with individuals tending to have a mix of brown and yellow coloring on their upper body. They can also be gray, red or greenish-brown. Most individuals have dark spots or splotches on their back and yellow or light-orange undersides and undersurface of the hind limbs.

Characteristic category

Similar Species

Characteristics
Similar Species
Characteristic category

Habitat

Characteristics
Habitat

The northern distinct population segment of mountain yellow-legged frogs live in California’s Sierra Nevada mountains in lakes, ponds, marshes, meadows and streams at elevations ranging from 4,500 to 12,000 feet (1,370 to 3,660 meters). The northern distinct population segment range extends from Fresno County, in the western Sierra Nevada, through portions of the Kern River drainage. The southern distinct population segment occupies the canyons of the Transverse Ranges in southern California.

Lake

A considerable inland body of standing water.

Mountain

A landmass that projects conspicuously above its surroundings and is higher than a hill.

River or Stream

A natural body of running water.

Wetland

Areas such as marshes or swamps that are covered often intermittently with shallow water or have soil saturated with moisture.

Geography

Characteristics
Range

The northern distinct population segment of this species live in California’s Sierra Nevada mountains in lakes, ponds, marshes, meadows and streams at elevations ranging from 4,500 to 12,000 feet (1,370 to 3,660 meters) and has a range that extends from Fresno County, in the western Sierra Nevada, through portions of the Kern River drainage. The southern distinct population segment lives in the canyons of the Transverse Ranges in southern California.

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Timeline

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