 Habitat loss , disease and climate change are thought to be responsible for the drastic decline in populations in recent years . Declines have been particularly intense in the western United States , Central America , South America , eastern Australia and Fiji ( although cases of amphibian extinctions have appeared worldwide ) . While human activities are causing a loss of much of the world ’ s biodiversity , amphibians appear to be suffering much greater effects than other classes of organism . Because amphibians generally have a two @-@ staged life cycle consisting of both aquatic ( larvae ) and terrestrial ( adult ) phases , they are sensitive to both terrestrial and aquatic environmental effects . Because their skins are highly permeable , they may be more susceptible to toxins in the environment than other organisms such as birds or mammals . Many scientists believe that amphibians serve as " canaries in a coal mine , " and that declines in amphibian populations and species indicate that other groups of animals and plants will soon be at risk . 
