The IUCN Red List Categories and Criteria have undergone an extensive review in recent years. This review has produced a clearer, more open, and easy-to-use system. The revised Categories and Criteria (IUCN Red List Categories and Criteria version 3.1) were adopted by IUCN Council in February 2000 and all new assessments and reassessments of taxa on the IUCN Red List must follow this revised system.
The conversion of all existing assessments on the Red List to the revised system will take time. In the interim, the current Red List includes assessments using both the 1994 Red List Categories and Criteria and the 2001 Categories and Criteria. To avoid confusion, all assessments using the 2001 Categories and Criteria are indicated by a ' ver 3.1 (2001) ' hyperlink, and all assessments using the 1994 Categories and Criteria are indicated by a ' ver 2.3 (1994) ' hyperlink.
All new assessments and reassessments on the IUCN Red List use the 2001 IUCN Red List Categories and Criteria version 3.1. Some assessments from 1996-2000 have also been converted to follow the revised categories and criteria (all of these are clearly indicated). Official translations of the IUCN Red List Categories and Criteria version 3.1 are available in English, French and Spanish:
Detailed guidelines on how to use the IUCN Red List Categories and Criteria have been developed and are regularly updated (English only):
IUCN Red List Index:
The IUCN Red List Index (RLI) measures overall trends in extinction risk for sets of species, based on genuine changes in their status over time. Further information about the RLI and how it is calculated can be found here. This Excel file contains macros that can automatically calculate the RLI and create appropriate graphs once you have entered suitable data (please enable macros):
Supporting Documentation & Appropriate Use:
All assessments must include standard documentation, as described in Annex 3 of the IUCN Red List Categories and Criteria. The Documentation Standards and Consistency Checks for IUCN Red List Assessments and Species Accounts provide detailed guidance on documenting Red List assessments. This includes completion of the standard Classification Schemes describing habitats, threats, etc. and the provision of a map showing the geographic distribution of the species. This document should be used for reference when preparing Red List assessment accounts.
Guidelines for Appropriate Uses of Red List Data have been developed to encourage and facilitate the use of IUCN Red List data and information, to tackle a broad range of important conservation issues. These address potential scientific, policy, management and educational uses of IUCN Red List data.
Assessments from 1996-2000 that have not been converted over to the revised system, use the 1994 categories and criteria.
Guidelines on the application of the IUCN Red List Criteria at national or regional levels have also been developed. In using these guidelines it is important to note that national or regional assessments are NOT eligible for inclusion on the IUCN Red List of Threatened Species, unless they are for endemic species. Official translations of these guidelines are available in English, French and Spanish:
An online resource is available to facilitate communication and knowledge-sharing about national and regional Red Lists, and to act as a centralised point for national and regional Red List data from around the world. This website includes a searchable species database, a library of downloadable documents, a network of individuals involved in national/regional Red Listing around the world, and a discussion forum for specific queries.
