Amphibians are one of nature's best indicators of overall environmental health, and their precipitous decline serves as a warning that we are in a period of significant environmental degradation. For example, the decline of the harlequin toad Atelopus varius (Critically Endangered) in Costa Rica and Panama has been dramatic. It has disappeared from suitable habitats, and the cause of its decline is possibly a result of the fungal disease, chytridiomycosis, the incidence of which could be related to extreme climatic events, in particular drought. Photo: © Robert Puschendorf.
Plants are the basis for life on Earth as we know it, giving us a breathable atmosphere, making food from sunlight, and providing structure for homes and habitats. But many of the world's plants are under threat. The Cucumber Tree Dendrosicyos socotrana (Vulnerable) is an unusual threatened endemic from the island archipelago of Soqotra, Yemen. Photo: © Anthony G. Miller.
The molluscs top the list of animals with the greatest numbers of recorded extinctions. These small creatures are vulnerable to extinction as they often have extremely limited ranges, move very short distances during their life and are hence sensitive to any disturbances. An example of a restricted range species is the Dlinza Forest Pinwheel Trachycystis clifdeni (Critically Endangered) confined to a small forest patch in KwaZulu-Natal, South Africa. Photo: © Dai G. Herbert.
There is a widespread perception that marine species are more resilient to extinction. However, there is a growing body of scientific evidence that shows that marine species are just as, if not even more, vulnerable to extinction as terrestrial and freshwater species. The Nassau Grouper Epinephelus striatus (Endangered) found widely across the Caribbean, is fished commercially and recreationally. Its population has declined by approximately 60%; over the last 30 years. Photo: © John E. Randall.
The number of threatened birds on the Red List continues to rise. The honeycreeper (Drepanididae) family endemic to Hawaii, USA, is particularly at risk with 13 of the 34 known species listed as Extinct and 18 as threatened, as a result of the impacts of invasive alien species. The Palila Loxioides bailleui (Endangered) is one of these threatened honeycreepers. Photo: © Jack Jeffrey Photography.
The current status of the world's mammal species is undergoing review through the Global Mammal Assessment project. Many new mammal species have been described in recent years that now require assessment. These include new species of lemur from Madagascar. Of the 33 lemurs assessed, 20 are listed as threatened, including Verreaux's Sifaka Lemur Propithecus verreauxi (Vulnerable), due to habitat loss and hunting. Photo: © Troy Inman.