 Dramatic declines in amphibian populations , including population crashes and mass localized extinction , have been noted since the late 1980s from locations all over the world , and amphibian declines are thus perceived to be one of the most critical threats to global biodiversity . In 2004 , the International Union for Conservation of Nature ( IUCN ) reported stating that currently birds , mammals , and amphibians extinction rates were at minimum 48 times greater than natural extinction rates — possibly 1 @,@ 024 times higher . In 2006 there were believed to be 4 @,@ 035 species of amphibians that depended on water at some stage during their life cycle . Of these , 1 @,@ 356 ( 33 @.@ 6 % ) were considered to be threatened and this figure is likely to be an underestimate because it excludes 1 @,@ 427 species for which there was insufficient data to assess their status . A number of causes are believed to be involved , including habitat destruction and modification , over @-@ exploitation , pollution , introduced species , climate change , endocrine @-@ disrupting pollutants , destruction of the ozone layer ( ultraviolet radiation has shown to be especially damaging to the skin , eyes , and eggs of amphibians ) , and diseases like chytridiomycosis . However , many of the causes of amphibian declines are still poorly understood , and are a topic of ongoing discussion . 
