Amphibians, Reptiles, & Fish
Amphibians, reptiles, and fish are found at all elevations within Sequoia and Kings Canyon National Parks. Many species can only be observed seasonally while others may be found at all times of the year. Their occurrence ranges from common (e.g. western fence lizards) to extirpated (locally extinct) (e.g. foothill yellow-legged frogs). The parks also have numerous non-native species such as the bullfrog and many species of fish, which were brought into naturally fishless high elevation lakes and streams to make the area more attractive to anglers.
The introduction of fish has had many unintended effects - the most dramatic being the resulting decline in mountain yellow-legged frog populations due to predation of frogs and tadpoles and the insects they feed on. Although once lumped together as a single species, mountain yellow-legged frogs have been split into the southern mountain yellow-legged frog (Rana muscosa) and the Sierra Nevada yellow-legged frog (Rana sierra). Both species occur within Sequoia and Kings Canyon National Parks and have disappeared from most of their native range. Although the introduction of trout into frog habitat is still considered a major cause of historic and current declines, the recent epidemic of amphibian chytrid fungus (Batrachochytrium dendrobatidis) has resulted in a another wave of population crashes, and appears to be the primary threat to the remaining populations of frogs occupying fishless habitat.
In order to monitor the density, distribution, and species composition of native fish, counts are occasionally conducted along set transects. The results of this project have informed park managers about the quality of native fisheries and also the extent to which non-native fish have become established in low and middle elevation streams.