International Union for Conservation of Nature and Natural Resources
以下でアクセス： 06 6月, 2016
The IUCN Red List of Threatened Species™ provides taxonomic, conservation status and distribution information on plants and animals that have been globally evaluated using the IUCN Red List Categories and Criteria. This system is designed to determine the relative risk of extinction, and the main purpose of the IUCN Red List is to catalogue and highlight those plants and animals that are facing a higher risk of global extinction (i.e. those listed as Critically Endangered, Endangered and Vulnerable). The numbers of species listed in each category in The IUCN Red List of Threatened Species change each time it is updated. This is a result of various factors, including species being assessed and added to The IUCN Red List for the first time, species being reassessed and moving into a different category of threat, and taxonomic revisions causing the total number of recognised species within a group to change. Dataset is organized by taxonomic group and shows numbers of threatened species listed in each version of The IUCN Red List since 1996: numbers of threatened species by major groups of organisms (1997–2012), changes in numbers of species in the threatened categories (CR, EN, VU) from 1997 to 2012.