High Quality Content by WIKIPEDIA articles! Dramatic declines in amphibian populations, including population crashes and mass localized extinctions, have been noted since the 1980s from locations all over the world. These declines are perceived as one of the most critical threats to global biodiversity, and several causes are believed to be involved, including disease, habitat destruction and modification, exploitation, pollution, pesticide use, introduced species, and increased ultraviolet-B radiation (UV-B). However, many of the causes of amphibian declines are still poorly understood, and the topic is currently a subject of much ongoing research. Calculations based on extinction rates suggest that the current extinction rate of amphibians could be 211 times the background extinction rate and the estimate goes up to 25,039–45,474 times if endangered species are also included in the computation.