An entire species of golden toad, observed breeding on a Costa Rican mountainside, vanished two years later and has not been seen since. Frogs examined during a middle-school science outing in Minnesota are found to have astonishingly high rates of physical deformities. At least three species of amphibians have apparently vanished from their former range in Yosemite National Park.
Amphibians are good indicators of significant environmental changes.
Amphibians, unlike people, breathe at least partly through their skin, which is constantly exposed to everything in their environment. Consequently, their bodies are much more sensitive to environmental factors such as disease, pollution, toxic chemicals, ultraviolet radiation, and habitat destruction. Multiple limbs, missing limbs, and facial abnormalities are the main developmental malformations seen. Malformed amphibians are now documented in 44 states, in 38 species of frogs and 19 species of toads, with estimates of deformities as high as 60 percent in some local populations. Scientists now agree that current numbers of reported malformations significantly exceed the normal statistical variation.