IUCN Red List Guidelines - The IUCN Red List of Threatened Species

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Red List Guidelines 8 assigned to taxa on the basis of quantitative criteria that are designed to reflect varying degrees of threat of extinction. These criteria will be discussed further in the next section. The category Near Threatened is applied to taxa that do not qualify as threatened now, but may be close to qualifying as threatened. The category Least Concern is applied to taxa that do not qualify (and are not close to qualifying) as threatened or near threatened. The remaining two categories do not reflect the threat status of taxa. The category Data Deficient highlights taxa for which sufficient information is lacking to make a sound status assessment. The inclination to assess taxa as Data Deficient may be very strong; it should be emphasized that assessors must use all data available in full when making a Red List assessment. Precise information on scarce taxa is usually lacking, and although the criteria are highly quantitative and defined, one can use projections, assumptions and inferences in order to place a taxon in the appropriate category. Since Data Deficient is not a category of threat, taxa placed in this category are not so obviously targets for conservation action, although their needs might be very great. Assessors should use whatever information is available and relevant to make assessments and place taxa into the Data Deficient category only when there is really no alternative. Guidance on handling uncertainty is especially relevant in the case of poorly known taxa (see section 3.2). The category Not Evaluated applies to taxa that have not yet been evaluated against the Red List Criteria. Taxa in all of the IUCN Red List Categories, except LC and NE, are normally presented in the Red List and, consequently, are referred to as "red-listed". The 2003 update of the IUCN Red List of Threatened Species and all subsequent updates will include all taxa assessed as LC and information about them will be documented, although these taxa would not be referred to as "red-listed". This is especially important, for example, for taxa that were redlisted in an earlier edition, but have since been down-listed. (Evaluated) (Adequate data) Not Evaluated (NE) (Threatened) Data Deficient (DD) Figure 2.1. Structure of the IUCN Red List Categories Extinct (EX) Extinct in the Wild (EW) Critically Endangered (CR) Endangered (EN) Vulnerable (VU) Near Threatened (NT) Least Concern (LC)
Red List Guidelines 9 Box 2.1. The IUCN Red List Categories EXTINCT (EX) A taxon is Extinct when there is no reasonable doubt that the last individual has died. A taxon is presumed Extinct when exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), throughout its historic range have failed to record an individual. Surveys should be over a time frame appropriate to the taxon’s life cycles and life form. EXTINCT IN THE WILD (EW) A taxon is Extinct in the Wild when it is known only to survive in cultivation, in captivity or as a naturalized population (or populations) well outside the past range. A taxon is presumed Extinct in the Wild when exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), throughout its historic range have failed to record an individual. Surveys should be over a time frame appropriate to the taxon's life cycle and life form. CRITICALLY ENDANGERED (CR) A taxon is Critically Endangered when the best available evidence indicates that it meets any of the criteria A to E for Critically Endangered, and it is therefore considered to be facing an extremely high risk of extinction in the wild. ENDANGERED (EN) A taxon is Endangered when the best available evidence indicates that it meets any of the criteria A to E for Endangered, and it is therefore considered to be facing a very high risk of extinction in the wild. VULNERABLE (VU) A taxon is Vulnerable when the best available evidence indicates that it meets any of the criteria A to E for Vulnerable, and it is therefore considered to be facing a high risk of extinction in the wild. NEAR THREATENED (NT) A taxon is Near Threatened when it has been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for or is likely to qualify for a threatened category in the near future. LEAST CONCERN (LC) A taxon is Least Concern when it has been evaluated against the criteria and does not qualify for Critically Endangered, Endangered, Vulnerable or Near Threatened. Widespread and abundant taxa are included in this category. DATA DEFICIENT (DD) A taxon is Data Deficient when there is inadequate information to make a direct, or indirect, assessment of its risk of extinction based on its distribution and/or population status. A taxon in this category may be well studied, and its biology well known, but appropriate data on abundance and/or distribution are lacking. Data Deficient is therefore not a category of threat. Listing of taxa in this category indicates that more information is required and acknowledges the possibility that future research will show that threatened classification is appropriate. It is important to make positive use of whatever data are available. In many cases great care should be exercised in choosing between DD and a threatened status. If the range of a taxon is suspected to be relatively circumscribed, if a considerable period of time has elapsed since the last record of the taxon, threatened status may well be justified. NOT EVALUATED (NE) A taxon is Not Evaluated when it is has not yet been evaluated against the criteria.
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IUCN Red List Guidelines - The IUCN Red List of Threatened Species

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