Amphibians are susceptible to changes to both aquatic and terrestrial habitats caused by human activities. Amphibians are declining throughout the world and 32% of species are threatened with extinction. Most disturbingly, many declines, and some extinctions, have occurred in locations where they are supposedly protected. Habitat destruction is the most significant cause of amphibian declines, but other factors, including ultraviolet radiation, contamination by agricultural and industrial chemicals, climate change, introduced predators and overexploitation also play an important role. The most dramatic declines and extinctions have been caused by a fungal disease, chytridiomycosis, which has recently become globally distributed.