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 23 species of crocodilians, 5 are currently listed as Critically
Endangered, 2 as Endangered, 3 as Vulnerable, 12 as Least Risk and 1 as Data
Deficient. 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 Risk (LR)
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
Category
Chinese
Alligator
Alligator
sinensis
CR
Philippine
Crocodile
Crocodylus
mindorensis
CR
Orinoco
Crocodile
Crocodylus
intermedius
CR
Siamese
Crocodile
Crocodylus
siamensis
CR
Indian Gharial
Gavialis
gangeticus
CR
Cuban Crocodile
Crocodylus
rhombifer
EN
False Gharial
Tomistoma
schlegelii
EN
American
Crocodile
Crocodylus
acutus
VU
Mugger
Crocodile
Crocodylus
palustris
VU
Dwarf Crocodile
Osteolaemus tetraspis
VU
Morelet’s Crocodile
Crocodylus moreletii
LR (cd)
Black Caiman
Melanosuchus niger
LR (cd)
American Alligator
Alligator mississippiensis
LR (lc)
Australian Freshwater Crocodile
Crocodylus johnstoni
LR (lc)
Nile Crocodile
Crocodylus niloticus
LR (lc)
New Guinea Freshwater Crocodile
Crocodylus novaeguineae
LR (lc)
Saltwater Crocodile
Crocodylus porosus
LR (lc)
Spectacled Caiman
Caiman crocodilus
LR (lc)
Broad-snouted Caiman
Caiman latirostris
LR (lc)
Yacare Caiman
Caiman yacare
LR (lc)
Cuvier’s Smooth-fronted Caiman
Paleosuchus palpebrosus
LR (lc)
Schneider’s Smooth-fronted Caiman
Paleosuchus trigonatus
LR (lc)
African
Slender-snouted Crocodile
Crocodylus
cataphractus
DD
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 five Critically
Endangered species of crocodilian (C. mindorensis, C. intermedius,
C. siamensis,
G. gangeticus, A. sinenis), each of which has a reintroduction element
associated with it. High human populations (eg Thailand, China, India,
Philippines) have been implicated as a threat to most of these species.
Trade was implicated in reduction of wild populations of Orinoco crocodiles, but
since 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 breeding of
reintroduced crocodiles in Vietnam, 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.
The CSG-Tomistoma Task Force is working with the Endangered Tomistoma
schlegelii, and habitats on the Isle of Youth in Cuba 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 three species of crocodilian in West Africa (C. niloticus,
C. cataphractus, O. tetraspis) is now a major focus of the CSG. A
recent sub-regional meeting was a first 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. Endanger. Species
Res. (in press).
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. J. Exp. Mar. Biol. Ecol. (in press).
Webb, G.J.W. (2008). The dilemma of accuracy in IUCN Red List
categories of extinction risk. Endanger. Species Res. (in press).
Critically
Endangered (CR)