Southern Mountain Yellow-legged Frog

Rana muscosa

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Rana muscosa is a small (1.6-3.5 inches in length) aquatic frog. From above, they have a yellowish to reddish-brown color with brown or black markings that resemble liche…

Southern Mountain Yellow-legged Frog illustration

How to identify

Rana muscosa is a small (1.6-3.5 inches in length) aquatic frog. From above, they have a yellowish to reddish-brown color with brown or black markings that resemble lichen. Its toe tips have a dusky color with the underside of the hind limbs and (sometimes) the belly displaying yellow or orange. This yellow coloration often widens out to the forelimbs. Dorsolateral folds are present but may sometimes be indistinct. Tadpoles are typically black to dark brown and are relatively large (exceeding 3.9 inches in total length).

Range

This species of frog is endemic to California in the USA. You can find them in the San Jacinto Mountains, San Gabriel Mountains in Southern California, San Bernardino Mountains, and the southern Sierra Nevada.

Habitat

These frogs are found in riverbanks, meadow streams, isolated pools. They seem to prefer sloping backs with vegetation and are typically found near a water source. They shelter in winter under ledges and in deep underwater crevices. Females deposit eggs by attaching them to rocks, vegetation or gravel in permanent freshwater sources like streams or lakes. They feed in a variety of invertebrates like beetles, ants, bees, wasps, flies, dragonflies, etc.

Similar species

The Sierra Nevada Yellow-legged Frog (Rana sierra) is almost identical to the Rana muscosa with the major difference being range. Rana sierra is found in the northern Sierra Nevada. Rana sierra has relatively shorter legs and a different mating call and has more of a transition between pulsed and noted sounds. The Foothill Yellow-legged Frog (Rana boylii) is small (1.46-3.23 inches) roughly similar in size. This frog has a dorsal background color of grey, brown, or reddish. They have a yellow coloration under the legs much brighter than Rana muscosa. The yellow coloration often spreads to cover the abdomen. The tadpoles of this frog have flattened tails. Sierran Tree Frog (Pseudacris sierra) has an average length range between (2-5 inches). It has a dorsal body coloring that may vary between green, tan, brown, grey, reddish, and cream but it is mostly found with green or brown coloration. There is a yellow color under the hind legs. Males have a darkened and wrinkled throat.