The IUCN Red List of Threatened Species is essentially a scientifically-based call to action for preventing the extinction of wild species around the world. Compiled by the IUCN’s Species Survival Commission (SSC), with support from the IUCN Species Program, the Red List guidelines and criteria have been modified at different times since its inception in 1963. But it still relies largely on a massive voluntary effort by global scientists to sustain the flow of Red List information. In this regard, SSC specialist groups such as the CSG have been responsible for undertaking Red List assessments. Indeed, specialist groups were involved in evaluating and testing the new generation of Red List criteria upon which these assessments are made.

Notwithstanding deficiencies in the Red List criteria (eg Webb 2008; Godfrey and Godley 2008; Seminoff and Shanker 2008), it still provides important guidance on the allocation of species to the Appendices of CITES. In the case of crocodilians the status of different species has more or less been in line with their listing on the CITES Appendices, and thus their ability to be traded internationally.

Of the 25 species of crocodilian, 7 are currently listed as Critically Endangered, 1 as Endangered, 3 as Vulnerable, 14 as Least Concern. These categories are defined by the Red List as:

• Critically Endangered (CR): considered to be facing an extremely high risk of extinction in the wild.
• Endangered (EN): considered to be facing a very high risk of extinction in the wild.
• Vulnerable (VU): considered to be facing a high risk of extinction in the wild.
• Least Concern (LC): widespread and abundant taxa, which can be further subdivided into one of three sub-categories: Conservation Dependent (cd), Near Threatened (nt) and Least Concern (lc).
• Data Deficient (DD): inadequate information to make a direct, or indirect, assessment of its risk of extinction based on distribution and/or population status. Data Deficient is not a category of threat.

Current IUCN Red List Categories for Crocodilians

Common Name Species Name Red List Category  Last Assessed Chinese Alligator Alligator sinensis CR  2017 Philippine Crocodile Crocodylus mindorensis CR  2012 Orinoco Crocodile Crocodylus intermedius CR  2017 Siamese Crocodile Crocodylus siamensis CR  2012 Gharial Gavialis gangeticus CR  2017 Cuban Crocodile Crocodylus rhombifer CR  2022 African Slender-snouted Crocodile  Mecistops cataphractus CR  2013         Tomistoma Tomistoma schlegelii EN  2022         American Crocodile Crocodylus acutus VU  2020 Mugger Crocodile Crocodylus palustris VU  2009 Dwarf Crocodile Osteolaemus tetraspis VU  1996         American Alligator Alligator mississippiensis LC  2018 Australian Freshwater Crocodile Crocodylus johnstoni LC  2016 Nile Crocodile Crocodylus niloticus LC  2017 New Guinea Freshwater Crocodile Crocodylus novaeguineae LC  2018 Saltwater Crocodile Crocodylus porosus LC  2019 Spectacled Caiman Caiman crocodilus LC  2016 Broad-snouted Caiman Caiman latirostris LC  2019 Yacare Caiman Caiman yacare LC 2019  Cuvier’s Smooth-fronted Caiman Paleosuchus palpebrosus LC  2018 Schneider’s Smooth-fronted Caiman Paleosuchus trigonatus LC  2018 Morelet’s Crocodile Crocodylus moreletii LC  2020 Black Caiman Melanosuchus niger LC/LR  2000  Osborn's Dwarf Crocodile  Osteolaemus osborni not assessed  - West African Crocodile Crocodylus suchus not assessed  - Central African Slender-snouted Crocodile Crocodylus leptorhynchus not assessed  -

The Red List categories apply to species at a global level. Thus, some species such as C. porosus may be secure in some countries (eg Australia, Papua New Guinea and Indonesia) but greatly reduced and/or threatened in others (eg Philippines, Malaysia, Singapore, etc.) - but at a global level C. porosus is not considered to be at high risk of extinction.

The Red List is used as a guide by the CSG to prioritise its work, but it also relies on a suite of other information when evaluating issues requiring specific action. For example, information from CSG members, NGOs and wildlife authorities is vital to directing the CSG’s efforts. Efforts to re-establish international trade on a legal and sustainable basis have clearly assisted the recovery of many crocodilian species, but some will require ongoing efforts.

Major conservation initiatives are currently underway with the 7 Critically Endangered species of crocodilian (C. rhombifer, C. mindorensis, C. intermedius, C. siamensis, G. gangeticus, A. sinensis), each of which has a reintroduction element associated with it. High human populations (eg Thailand, Vietnam, China, India, Philippines) have been identified as a threat to most of these species.

Trade was implicated in the reduction of wild populations of Orinoco Crocodiles, but due to increased protection and an active reintroduction program the status of this species has improved greatly. Trade remains a potential threat to the wild Siamese Crocodile population in Cambodia. There has been successful wild breeding of reintroduced crocodiles in Vietnam (Cat Tien National Park), but little is known about the status of the species in Indonesia (Kalimantan). Hybridisation between Siamese Crocodiles and Saltwater and Cuban Crocodiles in captivity is also an ongoing concern in relation to the wild Siamese Crocodile populations.

In Cuba, habitats on the Isle of Youth have been restocked with Cuban Crocodiles derived from captive breeding. Natural hybridisation between sympatric American Crocodiles and Cuban Crocodiles is a concern for the former species.

The population status of four species of crocodilian in West-Central Africa (C. suchus, C. cataphractus, O. osborni and O. tetraspis) is now a major focus of the CSG. Two recent regional meetings (2007, 2010) were a step towards increased participation in this important sub-region.

Suggested reading

Godfrey, M.H. and Godley, B.J. (2008). As we see it: seeing past the red - flawed IUCN global listings for sea turtles. Endangered Species Research 6: 155-159.

IUCN (2007). 2007 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 16 March 2008.

Seminoff, J.A. and Shanker, K. (2008). Marine turtles and IUCN Red Listing: A review of the process, the pitfalls, and novel assessment approaches. Journal of Experimental Marine Biology and Ecology 356: 52-68.

Webb, G.J.W. (2008). The dilemma of accuracy in IUCN Red List categories of extinction risk, as exemplified by hawksbill turtles Eretmochelys imbricata. Endangered Species Research 6: 161-172.