CSG Red List Authority

The IUCN Red List is the authoritative list of globally threatened animals and plants, now on-line, fully searchable and listing more than 35,000 animals. For crocodilians, the Red List has always been generated by the CSG (see Ross 2011 for detailed article on Red List process). The CSG used new criteria to assign Red List categories to all 23 crocodilians in 2002, and has re-evaluated several species since then, notably the Gharial (Gavialis gangeticus) and Cuban crocodile (Crocodylus rhombifer). However, as re-assessments for many crocodilian species have not been carried out since the mid- to late-1990s, they are now in the process of being updated:
  • American Crocodile (Crocodylus acutus) (final assessment)
  • Morelet's Crocodile (Crocodylus moreletii) (final assessment)
  • Siamese Crocodile (Crocodylus siamensis) (final assessment)
  • Philippine Crocodile (Crocodylus mindorensis) (final assessment)
  • Tomistoma (Tomistoma schlegelii) (final assessment)
  • Mugger Crocodile (Crocodylus palustris) (final assessment)
  • Chinese Alligator (Alligator sinensis)
  • Australian Freshwater Crocodile (Crocodylus johnstoni)
  • West African Crocodile (Crocodylus suchus)
  • Spectacled Caiman (Caiman crocodilus)
Red List categories and criteria are now based on "IUCN Red List categories and criteria Version 3.1 (2001)". Species are assigned to one of 7 categories if, and only if, they meet just one of the criteria applying to any category. Three are familiar "threatened" status categories (Vulnerable, Endangered and Critically Endangered), and the other categories accommodate species that are not threatened (Least Concern, Near Threatened, Extinct in the Wild, and Extinct). The criteria for threatened species cover 5 broad indices of extinction risk: A. Reduction in population size; B. Limited geographic range; C. Small population size combined with other risk factors (decline, population structure); D. Extremely small population size; E. Quantitative analysis indicating risk of extinction. Each criterion has detailed components and sub-criteria and objective, quantitative thresholds. The terminology for Red List criteria is specific to this use and carefully defined. There are rules and Guidelines for applying the criteria and a large body of case history and precedent to guide their application. The Red List only considers all of a species throughout its global range, but there are additional criteria to adjust assessments of local or regional populations.

For CSG, the final authority for Red Listing crocodilians lies with the CSG Chairman operating with the CSG Steering Committee. The Chairman has designated Dr. Perran Ross and Dr. Sally Isberg (since May 2016) to be the RLA focal point and coordinate our internal process. In consultation with the Chair and Steering Committee, the RLA focal point proposes small groups of assessors who generate the raw material of each species assessment. Each assessment is then independently reviewed by 2-3 experts additional to the assessors. Following approval by the Chair, reviewed assessments are passed to SSC Red List staff who perform their own review - largely to ensure correct application and interpretation of the criteria - and upon approval, pass the assessment into the publication stream.


Ross, P. (2011). Crocodile Red List Update. Crocodile Specialist Group Newsletter 30(2): 7-8. Download.