Siamese crocodile Temporal range: Pleistocene–Present, | |
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Siamese crocodile at Moscow Zoo | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Archosauromorpha |
Clade: | Archosauriformes |
Order: | Crocodilia |
Family: | Crocodylidae |
Genus: | Crocodylus |
Species: | C. siamensis |
Binomial name | |
Crocodylus siamensis Schneider, 1801 | |
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Synonyms | |
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The Siamese crocodile (Crocodylus siamensis) is a medium-sized freshwater crocodile native to Indonesia (Borneo and possibly Java), Brunei, East Malaysia, Laos, Cambodia, Myanmar, Thailand and Vietnam. The species is critically endangered and already extirpated from many regions. Its other common names include Siamese freshwater crocodile, Singapore small-grain, and soft-belly. [3]
Below is a cladogram based on a 2018 tip dating study by Lee & Yates simultaneously using morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data, [4] as revised by the 2021 Hekkala et al. paleogenomics study using DNA extracted from the extinct Voay . [5]
Crocodylinae |
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The Siamese crocodile is a medium-sized, freshwater crocodilian, with a relatively broad, smooth snout and an elevated, bony crest behind each eye. Overall, it is olive-green, with some variation to dark-green. [6] Young individuals measure 1.2 to 1.5 m (3 ft 11 in – 4 ft 11 in) and weigh 6 to 12 kg (13 to 26 lb), growing to a length of 2.1 to 3 m (6 ft 11 in – 9 ft 10 in) and a weight of 40 to 120 kg (88 to 265 lb) as an adult. [7] [8] Three individuals measuring 2.12 to 2.63 m (6 ft 11 in – 8 ft 8 in) and weighing 40–87 kg (88–192 lb) had bite force of 2,073–4,577 N (466–1,029 lbf ). [9] Large male individuals reach 4 m (13 ft 1 in) and 350 kg (770 lb) in weight. [10]
Siamese crocodiles occur in a wide range of freshwater habitats, including slow-moving rivers and streams, lakes, seasonal oxbow lakes, marshes and swamps. [11]
Despite conservation concerns, many aspects of C. siamensis life history in the wild remain unknown, particularly regarding its reproductive biology. [11]
Adults feed mainly on fish and snakes, but also eat amphibians and small mammals. [3]
Very little is known about the natural history of this species in the wild, but females build mound-nests constructed from scraped-up plant debris mixed with mud. [6] In captivity, these crocodiles breed during the wet season (April to May), laying between 15 and 50 eggs, which are then guarded until they hatch. [12] After incubation, the female will assist her young as they break out of their eggs and then carry the hatchlings to the water in her jaws. [13]
Pure, unhybridised examples of this species are generally unaggressive towards humans, [14] and there are only four confirmed attacks, none of them fatal. One was defending its young, [15] another was probably defending itself, [16] one was provoked, [17] and the reason for the last is unclear. [18] A fifth attack in 1928 that was probably done by a Siamese crocodile was fatal, with the victim being a child. [19]
Siamese crocodiles are under threat from human disturbance and habitat occupation, which is forcing remaining populations to the edges of their former range. [12] Extinct from 99% of its original range, the Siamese crocodile is considered one of the least studied and most critically endangered crocodilians in the world. [11] Although few wild populations remain, more than 700,000 C. siamensis are held on commercial crocodile farms in Southeast Asia. [11]
In 1992, it was believed to be extremely close to or fully extinct in the wild until 2000 when scientists from Fauna and Flora International and the Government of Cambodia's Forestry Administration confirmed the presence of Siamese crocodiles in the Cardamom Mountains in Southwest Cambodia. [20] [21] Since then, surveys have identified around 30 sites in Cambodia that contain wild Siamese crocodiles (conservatively estimated to number between 200 and 400 individuals in total), a tiny population in Thailand (possibly as few as two individuals, discounting recent reintroductions), a small population in Vietnam (possibly fewer than 100 individuals), Cat Tien National Park has about 200, and a more sizeable population in Laos. [22] In March 2005, conservationists found a nest containing juvenile Siamese crocodiles in the southern Lao province of Savannakhet. [23] There are no recent records from Malaysia, Burma or Brunei. A small but important population of the crocodiles is also known to live in East Kalimantan, Indonesia. [24] [25]
Factors causing loss of habitat include: conversion of wetlands for agriculture, chemical fertilisers use, use of pesticides in rice production, and an increase in the population of cattle. [26] The effects of warfare stemming from the conflicts in Vietnam, Laos, and Cambodia during the Vietnam War (from land mines to aerial bombardment) have also been factored. [27]
Many river systems, including those in protected areas, have hydroelectric power dams approved or proposed, which are likely to cause the loss of about half of the remaining breeding colonies within the next ten years. [11] One cause for habitat degradation via hydrological changes, for the Siamese crocodile, is the implementation of dams on the upper Mekong River and its major tributaries. [28] Potential impacts of dam construction include wetland loss and altered flooding cycle with a dry season flow 50% greater than under natural conditions. [29]
Illegal capture of wild crocodiles for supply to farms is an ongoing threat, as well as incidental capture/drowning in fishing nets and traps. [11] The Siamese crocodile currently has extremely low and fragmented remaining populations with little proven reproduction in the wild. [30]
Siamese crocodiles have historically been captured for skins and to stock commercial crocodile farms. In 1945, skin hunting for commercial farms was banned by the French colonial administration of Cambodia. [31] In the late 1940s, populations spurred the development of farms and harvesting wild crocodiles for stocking these farms. [32] Protection was abolished by the Khmer Rouge (1975–79) but later reinstated under Article 18 of the Fishery Law of 1987, which "forbids the catching, selling, and transportation of...[wild] crocodiles..." [31]
Crocodile farming now has a huge economic impact in the provinces surrounding Tonle Sap, where 396 farms held over 20,000 crocodiles in 1998. [31] Also, many crocodiles were exported from Cambodia since the mid-1980s to stock commercial farms in Thailand, Vietnam, and China. [33]
Despite legal protection, a profitable market exists for the capture and sale of crocodiles to farms since the early 1980s. [33] Chronic hunting has led to the decline of the wild Siamese crocodile. [22] [30]
This crocodile is classified as critically endangered on the IUCN Red List, and is listed on Appendix I of CITES. [2] It is one of the most endangered crocodiles in the wild, although it is extensively bred in captivity. [12]
Yayasan Ulin (The Ironwood Foundation) ran a small project to conserve an important wetland habitat in the area of East Kalimantan which is known to contain the crocodiles. [34]
In Cambodia Fauna and Flora International and the Government of Cambodia's Forestry Administration have established the Cambodian Crocodile Conservation Programme for the protection and recovery of Siamese crocodiles. This programme works with a network of indigenous villages who are helping to protect key sites such as Veal Veng Marsh (Veal Veng District), the Tatai River (Thmar Bang District) and the Araeng River. The latter is considered to have the second largest population of Siamese crocodiles in the world, but is currently threatened by the proposed construction of a massive dam in the river. During the heavy monsoon period of June–November, Siamese crocodiles take advantage of the increase in water levels to move out of the river and onto large lakes and other local bodies of water, returning to their original habitat once water levels start receding back to their usual levels. [35]
The Cambodian Crocodile Conservation Programme conducted DNA analysis of 69 crocodiles in Phnom Tamao Wildlife Rescue Centre in Cambodia 2009, and found 35 of them were purebred C. siamensis. Conservationists from the Forestry Administration and Fauna and Flora International subsequently launched a conservation breeding program at the Centre. Since 2012, approximately 50 purebred Cambodian Siamese crocodiles have been released into community-protected areas to reinforce the depleted wild populations. [36]
Poaching is a severe threat to this species, with the value of wild Siamese crocodiles reaching hundreds of dollars in the black market, where they are illegally taken into crocodile farms and hybridized with other, larger species. [37] The total wild population is unknown, since most groups are in isolated areas where access is extremely complicated. A number of captively held individuals are the result of hybridization with the saltwater crocodile, but several thousand "pure" individuals do exist in captivity, and are regularly bred at crocodile farms, especially in Thailand.
Pang Sida National Park in Thailand, near Cambodia, has a project to reintroduce Siamese crocodile into the wild. A number of young crocodiles have been released into a small and remote river in the park, not accessible to visitors. [22]
The Wildlife Conservation Society (WCS) is working with the government of Laos on a new programme to save this critically endangered crocodile and its wetland habitat. In August, 2011, a press release announced the successful hatching of a clutch of 20 Siamese crocodiles. These eggs were then incubated at the Laos Zoo. This project represents a new effort by WCS to conserve the biodiversity and habitat of Laos’ Savannakhet Province, promotes conservation of biodiversity for the whole landscape, and relies on community involvement from local residents. [38]
In September 2021, eight hatchlings were found in a wildlife sanctuary in eastern Cambodia. [39]
In Cambodia's Southern Cardamom National Park, sixty Siamese crocodiles from five distinct nests successfully hatched in July 2024. This marks the largest wild breeding record of the species this century and significantly enhances the survival prospects of this critically endangered reptile. [40] [41]
High priority projects include: [42]
Other projects include: [35]
A Malay folktale features a crocodile that is outwitted by a mouse-deer and buffaloes. [43] A Siamese crocodile has been cited in the Thai folklore of Central Thailand's Krai Thong ("ไกรทอง") tales have known as well, [44] and was taken to create a television series and movies several times. [45]
In Vietnam a major literary juncture occurred in 1282 when a troublesome crocodile came to inhabit a stretch of the Red River. The scholar Nguyễn Thuyên wrote "Ode to the crocodile" and threw it into the river as an appeal to the beast whereupon the crocodile departed. It was remarkable as historians recorded it as one of the first pieces ever written in the demotic script Chữ Nôm instead of classical Chinese; the emperor amply rewarded the scholar for his literary deed. It marked a shift in Vietnamese literature as the Nôm script gained significant traction as a worthy vehicle for literary works. [46]
A Siamese crocodile stars as the titular monster in the 1978 Thailand film Crocodile . [47]
Crocodiles or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant members of the order Crocodilia, which includes the alligators and caimans, the gharial and false gharial among other extinct taxa.
The saltwater crocodile is a crocodilian native to saltwater habitats, brackish wetlands and freshwater rivers from India's east coast across Southeast Asia and the Sundaic region to northern Australia and Micronesia. It has been listed as Least Concern on the IUCN Red List since 1996. It was hunted for its skin throughout its range up to the 1970s, and is threatened by illegal killing and habitat loss. It is regarded as dangerous to humans.
Eld's deer, also known as the thamin or brow-antlered deer, is an endangered species of deer endemic to South and Southeast Asia.
The Madras Crocodile Bank Trust and Centre for Herpetology (MCBT) is a reptile zoo and herpetology research station, located 40 km (25 mi) south of the city of Chennai, Tamil Nadu, India. The centre is both a registered trust and a recognized zoo under the Wild Life (Protection) Act, 1972 and comes under the purview of the Central Zoo Authority, Ministry of Environment, Forest and Climate Change, Government of India. The establishment is located on a 8.5 acres (3.4 ha) site covered by coastal sand forests, along the coast of Bay of Bengal.
The mugger crocodile is a medium-sized broad-snouted crocodile, also known as mugger and marsh crocodile. It is native to freshwater habitats from southern Iran to the Indian subcontinent, where it inhabits marshes, lakes, rivers and artificial ponds. It rarely reaches a body length of 5 m and is a powerful swimmer, but also walks on land in search of suitable waterbodies during the hot season. Both young and adult mugger crocodiles dig burrows to which they retreat when the ambient temperature drops below 5 °C (41 °F) or exceeds 38 °C (100 °F). Females dig holes in the sand as nesting sites and lay up to 46 eggs during the dry season. The sex of hatchlings depends on temperature during incubation. Both parents protect the young for up to one year. They feed on insects, and adults prey on fish, reptiles, birds and mammals.
The Nile crocodile is a large crocodilian native to freshwater habitats in Africa, where it is present in 26 countries. It is widely distributed in sub-Saharan Africa, occurring mostly in the eastern, southern, and central regions of the continent, and lives in different types of aquatic environments such as lakes, rivers, swamps and marshlands. It occasionally inhabits deltas and brackish lakes and rarely also saltwater. Its range once stretched from the Nile Delta throughout the Nile River. Lake Turkana in Kenya has one of the largest undisturbed Nile crocodile populations.
The American crocodile is a species of crocodilian found in the Neotropics. It is the most widespread of the four extant species of crocodiles from the Americas, with populations present from South Florida, the Caribbean islands of Cuba, Jamaica, Hispaniola, and the coasts of Mexico to as far south as Peru, Ecuador, Colombia, and Venezuela.
The gharial, also known as gavial or fish-eating crocodile, is a crocodilian in the family Gavialidae and among the longest of all living crocodilians. Mature females are 2.6 to 4.5 m long, and males 3 to 6 m. Adult males have a distinct boss at the end of the snout, which resembles an earthenware pot known as a ghara, hence the name "gharial". The gharial is well adapted to catching fish because of its long, narrow snout and 110 sharp, interlocking teeth.
The freshwater crocodile, also known commonly as the Australian freshwater crocodile, Johnstone's crocodile, and the freshie, is a species of crocodile native to the northern regions of Australia. Unlike its much larger Australian relative, the saltwater crocodile, the freshwater crocodile is not known as a man-eater, although it bites in self-defence, and brief, nonfatal attacks have occurred, apparently the result of mistaken identity.
The Orinoco crocodile is a critically endangered crocodile. Its population is very small, and they can only be found in the Orinoco river basin in Venezuela and Colombia. Extensively hunted for their skins in the 19th and 20th centuries, it is one of the most endangered species of crocodiles. It is a very large species of crocodilian; males have been reported up to 6.8 m in the past, weighing over 900 kg (2,000 lb), but such sizes do not exist today, 5.2 m being a more widely accepted maximum size. A large male today may attain 4.2 m in length and can weigh up to 450 kg (1,000 lb), while females are substantially smaller with the largest likely to weigh around 225 kg (496 lb). Sexual dimorphism is not as profound as in other crocodilian species. The coloration is light even in adults.
The Philippine crocodile, also known as the Mindoro crocodile, the Philippine freshwater crocodile, the bukarot in Ilocano, and more generally as a buwaya in most Filipino lowland cultures, is one of two species of crocodiles found in the Philippines; the other is the larger saltwater crocodile (Crocodylus porosus). The Philippine crocodile, the species endemic only to the country, went from data deficient to critically endangered in 2008 from exploitation and unsustainable fishing methods, such as dynamite fishing. Conservation methods are being taken by the Dutch/Filipino Mabuwaya foundation, the Crocodile Conservation Society and the Zoological Institute of HerpaWorld in Mindoro island. It is strictly prohibited to kill a crocodile in the country, and it is punishable by law.
The giant barb, Giant Siamese carp, or simply Siamese carp is the largest species of cyprinid in the world. These migratory fish are found only in the Mae Klong, Mekong, and Chao Phraya River basins in Indochina. Populations have declined drastically due to habitat loss and overfishing, and the giant barb is now considered critically endangered.
The New Guinea crocodile is a small species of crocodile found on the island of New Guinea north of the mountain ridge that runs along the centre of the island. The population found south of the mountain ridge, formerly considered a genetically distinct population, is now considered a distinct species, Hall's New Guinea crocodile. In the past it included the Philippine crocodile, C. n. mindorensis, as a subspecies, but today they are regarded as separate species. The habitat of the New Guinea crocodile is mostly freshwater swamps and lakes. It is most active at night when it feeds on fish and a range of other small animals. A female crocodile lays a clutch of eggs in a nest composed of vegetation and she lies up nearby to guard the nest. There is some degree of parental care for newly hatched juveniles. This crocodile was over-hunted for its valuable skin in the mid 20th century, but conservation measures have since been put in place, it is reared in ranches and the International Union for Conservation of Nature (IUCN) lists it as being of "Least Concern".
Morelet's crocodile, also known as the Mexican crocodile or Belize crocodile, is a modest-sized crocodilian found only in the Atlantic regions of Mexico, Belize and Guatemala. It usually grows to about 3 metres (10 ft) in length. It is a species at least concern for extinction according to the International Union for Conservation of Nature. The species has a fossil record in Guatemala.
The West African slender-snouted crocodile, or slender-snouted crocodile, is a critically endangered species of African crocodile. It is one of five species of crocodile in Africa, the other four being the Central African slender-snouted, Nile, West African and dwarf crocodiles.
The Tonlé Sap Biosphere Reserve is a unique ecological phenomenon surrounding the Tonlé Sap or Great Lake of Cambodia. In 1997, it was successfully nominated as a UNESCO Biosphere Reserve.
The Cuban crocodile is a small-medium species of crocodile endemic to Cuba. Typical length is 2.1–2.3 m (6.9–7.5 ft) and typical weight 70–80 kg (150–180 lb). Large males can reach as much as 3.5 m (11 ft) in length and weigh more than 215 kg (474 lb). Despite its smaller size, it is a highly aggressive animal, and potentially dangerous to humans.
Peter Brazaitis is an American herpetologist and forensic specialist in herpetology and worked for the Wildlife Conservation Society from 1954 to 1998. He began as a reptile keeper at the Bronx Zoo, became Senior Keeper in 1967, Assistant Animal Manager in 1970, and Superintendent of Reptiles in 1972. In 1988, he transferred to the Central Park Wildlife Center as Assistant Curator of Animals and became Curator of Animals in 1990, a position he held until his retirement in 1998.
Crocodile farming in the Philippines refers to agricultural industries involving the raising and harvesting of crocodiles for the commercial production of Crocodile meat and crocodile leather.
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