Sierra Nevada Yellow-legged Frog (Rana sierrae)

Common Name: Sierra Nevada Yellow-legged Frog
Scientific Name: Rana sierrae
Family: Ranidae – True Frog Family
Locations: United States – California and Nevada (probably extinct there)
Size: 2 – 3 inches (5 – 7.6 cm)

As the name suggests, the Sierra Nevada Yellow-legged Frog lives in the Sierra Nevada Mountains at elevations between 4500 to 12000 feet. They are found near streams, lakes, ponds, and marshes.

Once the Sierra Nevada Yellow-legged Frog emerge from their overwintering sites after the snow melts, they move to breeding sites. This varies between elevations with low elevations starting in April while higher elevations start in June or possibly July. After they arrive, the male frogs start to call out to attract the females of the species. Next, the male frog grasps the female frog from behind in amplexus. Then, the female frog lays her eggs and the male frog fertilizes them. The female frogs lay between 15 to 350 eggs. The eggs hatch after 16 – 21 days. Once again, the time the tadpoles take to complete their metamorphosis depends on their elevation. At high elevations, the tadpoles can take between 1 – 4 years to complete their metamorphosis. At lower elevations, the tadpoles can complete the metamorphosis in a couple months.

The Sierra Nevada Yellow-legged Frog is a federally listed endangered species by the United States. The International Union for the Conservation of Nature (IUCN) Red List assesses the frog as Vulnerable to Extinction. One study found that 92% of the population have become extinct. There are two primary causes for the decline: Chytrid Fungus and introduced non-native species.  Chytrid Fungus is a deadly pathogen that has affected frogs around the world. It causes the skin of the frog to harden preventing air flow in the frog. Introduced trouts have preyed on the tadpoles of the frogs, causing declines. Experiments of complete removal of the trouts in lakes have shown to increase the Sierra Nevada Yellow-legged Frogs. Other smaller threats to the frog are climate change, pollution, and habitat destruction due to cattle grazing.