Yosemite is home to a small variety of amphibians as compared to more temperate or tropical climates. This may be due in part to past glacial activity, and in part the park's Mediterranean climate which includes hot, dry summers and cold, wet winters.
Eleven native and one-non-native amphibian species can be found in Yosemite. Three of these species—the Sierra Nevada yellow-legged frog, the Yosemite toad, and the Mount Lyell Salamander—are only found in the Sierra Nevada of California. One species, the foothill yellow-legged frog, has not been documented in the park in many years. This species, however, was recently documented just outside the park in the Tuolumne River. Park scientists are surveying the river inside the park in the hopes of locating some individuals.
The diminutive Pacific treefrog is Yosemite's most common frog species. You can find them throughout the park, at all elevations and in nearly all habitats. Treefrogs are even found in cracks on the face of El Capitan.You are most likely to hear treefrogs calling in meadows and ponds during the spring.
The Sierra Nevada yellow-legged frog was once the most abundant vertebrate found in Yosemite’s high-country lakes and streams. Visitors used to describe finding frogs in such great numbers that “it was difficult to walk without stepping on them.” Today, the Sierra Nevada yellow-legged frog is one of the world’s most critically endangered amphibians, having lost at least 93% of their populations. The introduction on nonnative trout and amphibian chytrid fungus are the primary reasons for their decline. They are federal and state candidates for listing as endangered.
The Yosemite toad has also experienced serious declines, losing at least 50% of their populations. This once common wet meadow species is rarely encountered by the public today; however, its uniquely different coloration between the sexes, musical call, and stately toad behavior is a treat for those fortunate enough to encounter them. Visitors to Yosemite's high-country have described the Yosemite toad's call as a strikingly clear, high-pitched trill with its mellow notes being a "pleasing addition to the chorus of bird songs just after the snow leaves."
The nonnative bullfrog is a voracious predator that has been implicated in the decline of many native animals. Bullfrogs eat anything they can get their mouth around including: native frogs, toads, salamanders, small mammals, snakes, turtles, even birds and bats. Bullfrogs probably played a part in the loss of populations of western pond turtles and California red-legged frogs in the park. The California red-legged frog no longer occurs in the park. Because bullfrogs have a huge impact on the native wildlife, we have been eradicating them from Yosemite Valley.
Scientists published two papers on the effects of chytrid fungus on the mountain yellow-legged frog species complex, which includes the Sierra Nevada yellow-legged frog (Rana sierrae), and the Sierra Madre yellow-legged frog (Rana muscosa). The Sierra Nevada yellow-legged frog occurs in Yosemite.