Chapter 19 Endangered Species 465 Copyright Goodheart-Willcox Co., Inc. IUCN Animal Classifi cation The IUCN developed a system with nine classifi cations to help categorize species at high risk of global extinction. The IUCN Red List and the IUCN’s system of classifi cation is used by wildlife departments, government agencies, natural resource planners, and many other organizations and individuals involved in protecting endangered species and main- taining biodiversity. • Extinct species (EX) are those with no living specimens. • Extinct in the wild species (EW) are those with some specimens living in captivity but with no specimens living in the wild. • Critically endangered species (CR) are species facing an extremely high risk of becoming extinct. • Endangered species (EN) are those facing a high risk of extinction in the wild, Figure 19-2A. • Vulnerable species (VU) are those likely to become endangered unless action is taken to identify and correct factors that will likely lead to its demise. • Near threatened species (NT) are wildlife species that may face population decline in the future and should be monitored for changes, Figure 19-2B. • Species labeled as least concern (LC) species are wildlife species that are doing well and have no cause for concern, Figure 19-2C. • Data defi cient (DD) identifi es when there is inadequate information on abundance or distribution to make an assessment about a species’ status. • The fi nal category is not evaluated. IUCN Species Criteria The criteria used to determine if a species is vulnerable, endangered, or critically endangered are population reduction rate, geographic range, population size, population restrictions, and probability of extinction. Photograph by Susan Berescik B Photograph by Susan Berescik Figure 19-2. A—The Utah prairie dog (Cynomys parvidens) is currently listed as endangered (EN) on the Red List. B—The American bison (Bison bison) is listed as near threatened (NT) on the Red List and as endangered on the US Federal List. C—The nine-banded armadillo (Dasypus novemcinctus) is listed as least concern (LC) on the Red List. C Photograph by Susan Berescik A