The Yosemite toad is an endemic species to the Sierra Nevada.

One-third of Yosemite National Park’s amphibian species are found nowhere else in the world than in the Sierra Nevada region. That makes Yosemite an important place—or home—for four of the 12 amphibian species requiring the park’s habitat for their survival. Those endemic species, having such a connected relationship to place, are the Mount Lyell salamander, Sierra Nevada ensatina, Sierra Nevada yellow-legged frog, and Yosemite toad.

Amphibians are ectotherms, depending on outside sources of heat to warm their bodies. That’s why you will find Sierra Nevada yellow-legged frogs sunning themselves beside high mountain lakes. Amphibians’ skin—which lacks scales, fur, or hair—is moist or slimy to the touch, and water is absorbed and lost through the skin. Amphibians “breathe”—exchanging oxygen and carbon dioxide—through their skin to some extent. Even amphibians with lungs must breathe through their skin in some way.

Scientists study the Sierra Nevada yellow-legged frog to increase its population size.

The Greek-rooted word “amphibian” refers to “double life” or the fact that typical amphibians have an aquatic larval stage—tadpoles—that metamorphose into air-breathing adults, capable of living on land. Many of the amphibians found in Yosemite have adapted to a more terrestrial lifestyle and do not have a free-living aquatic life stage. The arboreal salamander, gregarious slender salamander, hell hollow slender salamander, Sierra Nevada ensatina, and Mount Lyell salamander lay their eggs in moist nesting cavities on land, rather than under water, and the terrestrial eggs hatch into fully formed miniature adults. Other Yosemite amphibians, such as the Sierra newt, exhibit the more typical double-life stages associated with amphibians. In terms of diet, adult amphibians often feed on insects, spiders, snails and other small invertebrates, and other amphibians at all life stages. Amphibians, at a larval stage, feed on a wider variety of foods, such as frog tadpoles that feed, primarily, on algae and aquatic plants.

The park’s scientists work to improve the future of the native amphibians by controlling the non-native American bullfrog that is a voracious predator eating native frogs and salamanders, small mammals, snakes, turtles, even birds and bats. Because bullfrogs have a huge impact on the native wildlife, the park has been actively eradicating them from Yosemite Valley.

Salamanders and Newts

Having tails and resembling lizards superficially in appearance, caudates are adapted to the region’s Mediterranean climate. During dry periods, the animals retreat to moist natural and human-made refuges, such as rodent burrows, seepages, rock fissures, mine shafts, and rotten logs. Because they retreat to prevent water loss, summer visitors are not likely to see them. Visitors are most likely to see salamanders and newts during wet periods when the animals emerge to forage on the surface at night or to breed. 

Yosemite’s lone newt species, the Sierra newt, is the park’s most visible caudate, moving often in a slow motion between their retreats on land and their breeding sites in nearby ponds, streams, and rivers. The first fall rains usually initiate their migration, which takes place between December and May. During this time, park visitors may observe them crossing roads or trails. While in breeding sites, adult males develop a smooth skin and flattened tail that allows them to thrive in the aquatic environment. The rest of the year, their skin is thick, rough, and relatively unvascularized to reduce the amount of water lost to evaporation while living on land.

Watch for the Pacific treefrog, the most common frog in Yosemite that's found at all elevation levels.

Frogs and Toads

Anurans are short-bodied, tail-less amphibians that have larger hind legs modified for climbing or swimming. The common question: What is the difference between frogs and toads? Toads are terrestrial or burrowing creatures that have thick, warty skin and short legs, while frogs generally have smooth, moist skin, and longer legs. Yosemite’s frogs spend most of their lives in or near water, while toads get out on land a little more—possibly finding their way into your campsite.

Two species of toads and four species of frogs were once found in Yosemite. Today, only two species of native frogs, two species of toads, and one non-native frog are likely to found in the park. The California red-legged and foothill yellow-legged frogs have declined throughout their range and are believed to be extirpated (no longer occur in the park) leading both species to be listed as a species of concern by the state of California. The California red-legged frog is listed, also, as threatened under the federal Endangered Species Act, and the Sierra Nevada yellow-legged frog and Yosemite toad have also experienced precipitous population declines and are candidate species under the Endangered Species Act.   

The diminutive Pacific treefrog, the most common of Yosemite’s frog species, can be found at nearly all elevations in nearly all habitats. Most often heard calling around meadows and ponds in the spring, this treefrog has declined, according to park surveys, although not as dramatically as those of the Sierra Nevada yellow-legged frog or Yosemite toad.

Overall, with two species possibly extirpated in the park and two more on trajectories toward extinction, Yosemite National Park’s relatively undisturbed landscape and long-term data allow scientists to test hypotheses about what is causing declines here, and, throughout the world for amphibians.

The public can follow along with a High-elevation Aquatic Resources Management Plan [82 kb PDF] Environmental Assessment expected to be ready for public comment in summer 2009. Additional details exist on the park's experimental fish removal to assist the Sierra Nevada yellow-legged frog [101 kb PDF].

View a list of Yosemite’s amphibian species and a list of the park’s special status animal species.