Lead CDFW biologists: Dawne Emery, Jim Erdman
Endemic (found only in) to California, the Yosemite toad range is in high elevations in the Sierra Nevada Mountains, from the Ebbets Pass area of Alpine County south to the Spanish Mountains area in Fresno County. Yosemite toads occur on both sides of the Sierra Crest. Recent data reveal patchy extirpations rangewide, but particularly at east side Sierra Nevada elevations less than 7,000 ft. The toad is federally listed as a candidate species, and state designated as a Species of Special Concern.
Aside from documenting breeding locations through our local high mountain lake survey efforts, other management actions to protect the toad include our involvement with drafting a Conservation Assessment and Strategy through the U.S. Forest Service and reviewing and commenting upon projects, primarily on National Forest lands, that may impact the toad. Threats to the toad include pathogens(the same Chytrid disease that is impacting amphibians worldwide), pesticides, livestock grazing, ultraviolet radiation, introduction of non-native fishes, acidification from atmospheric deposition, nitrate deposition, recreational activities, and drought are among the many risk factors that have been identified as potentially impacting this species and its habitat.
Studies have taken place that address two of the above listed impacts specific to Yosemite toad. With regard to nonnative trout as an impact: One feeding study showed that trout learn that Yosemite toads are unpalatable (taste bad) and refuse them as food, even when hungry. However, colleagues have witnessed anglers illegally using Yosemite toads as bait, so recreational fishing may still be ï¿½on the hookï¿½ as far as impacting the toad! Another study tried to determine whether or not grazing was actually a detriment to Yosemite toads, but the study lacked a control.
Yosemite toads are sexually dimorphic (male and female have different appearances). Yosemite toads often utilize ephemeral ponds for breeding, as metamorphosis from egg to tadpole to sub-adult can occur within the summer season. Yosemite toads need water for breeding habitat, but unlike the black toad, Yosemite toads use nearby terrestrial meadow habitats for foraging, refuge, and movements, and they overwinter in mammal burrows, willow thickets, under boulders and logs, and underground.