| pesticides are involved with population declines of amphibians in the california sierra nevadas. | several species of frogs and toads are in serious decline in the sierra nevada mountains of california. these species include the threatened red-legged frog ( rana aurora ), foothill yellow-legged frog ( r. boylii ), mountain yellow-legged frog ( r. muscosa ), cascades frog ( rana cascadae ), western toad ( bufo boreas ) and yosemite toad ( b. canorus ). for many of these species current distributions are down to 10% of historical ranges. several factors including introduced predators, habitat l ... | 2001 | 12805670 |