Siamese Crocodile

Siamese Crocodile

Scientific Name: Crocodylus siamensis
Common Names: Siamese Crocodile

Maximum adult length: 3 metres (9.8 feet)


N.B. Exceptionally large specimens can be found in all species of crocodilian.


The Siamese crocodile is a freshwater crocodile native to Asia. Little is known about this critically endangered species, which has already been eradicated from many regions. They prefer slow moving waters like swamps, rivers, and lakes. In captivity, both male and female Siamese crocodiles look after newly hatched crocs.


The Siamese crocodile is classified as Critically Endangered on the IUCN Red List of Threatened Species.


Red List Category & Criteria: Critically Endangered A2cd ver 3.1
Year Published: 2012
Date Assessed: 2012-02-23
Population Trend: Decreasing


siamese status

The Siamese crocodile historically occurred over much of mainland Southeast Asia as well as parts of Indonesia. Its current range is greatly diminished and fragmented. Extant populations are in Cambodia, Indonesia, Lao PDR, Thailand and Viet Nam. In Viet Nam, wild populations are possibly extirpated, the first range nation where this has occurred, although a reintroduction programme has been implemented.


Countries: Cambodia; Indonesia (Java – Possibly Extinct, Kalimantan); Lao People’s Democratic Republic; Thailand

Siamese crocodiles occur in a wide range of lowland freshwater habitats, including slow-moving rivers and streams, lakes, marshes and swamps. During the wet season, individuals disperse across flooded landscapes (one radio-tracked individual in Cambodia moved up to 25 km before returning to a dry season site).

Similar to many other crocodilians, Siamese crocodiles feed on a wide variety of prey such as invertebrates, frogs, reptiles, birds and mammals, including carrion. Adults feed mainly on fish, but also eat amphibians, reptiles and small mammals.

Siamese crocodiles are among the most threatened crocodilians. In 1992 it was reported as virtually extinct in the wild and in 1996 was accorded the IUCN Red List status of ‘Critically Endangered’. This status remains unchanged.


Field surveys, nearly all conducted since 2000, have confirmed that extant populations persist, but that all are severely diminished and fragmented. Over the past decade new information on the ecology of the species has been documented, although Siamese crocodiles remain one of the least known crocodilians.


Commercial hunting for the skin trade and collection of live animals to stock crocodile farms, in the mid- and late-twentieth century respectively, are considered to be the principal causes for its decline. Current threats include illegal collection of eggs, juveniles and adults, habitat loss, incidental capture with fishing gear, and the vulnerability of extant populations due to their small size.


Most conservation efforts for the Siamese crocodile were initiated in the past decade and are relatively recent. Conservation priorities have been identified and a management plan to protect breeding sites was prepared. Community workshops were held in 2006 and 2007 to document local knowledge of crocodiles.


In Thailand, a re-introduction programme was initiated by the Royal Thai Forest Service and Crocodile Management Association of Thailand, with 20 crocodiles released in Pang Sida National Park in 2005 and 2006. Few crocodiles were detected during subsequent monitoring and further releases are being considered. Severe flooding in Thailand in 2011 hindered the implementation of some re-introduction plans. In Viet Nam, 60 captive individuals were released in Cat Tien National Park between 2001 and 2004 and the population has been irregularly monitored since then. The most recent surveys (2010-2011) confirmed that the population has increased in size, but that crocodiles continue to be hunted by local residents.


The large captive populations of Siamese crocodiles held on farms represent a potential source for re-introduction programs, and farms in Thailand and Viet Nam have donated crocodiles for this purpose. Genetically pure crocodiles have been found in captive holdings in Cambodia.


Current and on-going threats include the illegal collection of eggs and crocodiles, habitat loss and degradation, and incidental capture/drowning in fishing gear. In Cambodia, most river systems with extant Siamese crocodiles are targeted for large-scale hydroelectric dams. Construction of some of these dams has already begun and has resulted in the loss of breeding habitat and increased collection and killing of crocodiles.


On the basis of limited data, the global wild population of the Siamese crocodile may comprise fewer than 1,000 mature individuals.


Est. wild population: Less than 1,000
Main conservation threats: Habitat destruction, illegal hunting and persecution


IUCN Red List (September, 2014)


At the zoo

We currently have a pair of Siamese crocodiles at the zoo, Hugo and Rebecca. Another pair, the smaller Scar and Hayley, are on loan to another UK zoo.


With less than 1,000 mature adults left in the wild – some reports suggesting as few as 500, this critically endangered species is at even greater risk of hybridisation than other crocodilian species. In March 2013, following DNA testing, we received excellent news that all four individuals at Crocodiles of the World are genetically pure Siamese crocodiles.


We now regularly breed our Siamese crocodiles (the first zoo in the UK to do so), and could potentially send some back to Cambodia for release into the wild in future (although this is a more complex issue than people realise).



  • Katie Smith
  • David Smith

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