Siamese crocodile

Source: Wikipedia, the free encyclopedia.

Siamese crocodile
Temporal range:
Ma[1]
Crocodylus siamensis in moscow zoo 01.jpg
Siamese crocodile at Moscow Zoo

Critically Endangered (IUCN 3.1)[2]
CITES Appendix I (CITES)[2]
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Crocodilia
Family: Crocodylidae
Genus: Crocodylus
Species:
C. siamensis
Binomial name
Crocodylus siamensis
Schneider
, 1801
Crocodylus siamensis Distribution.png
Synonyms
  • Crocodylus ossifragus Dubois, 1908

The Siamese crocodile (Crocodylus siamensis) is a medium-sized freshwater

critically endangered and already extirpated from many regions. Its other common names include Siamese freshwater crocodile, Singapore small-grain, and soft-belly.[3]

Phylogeny

Below is a

stratigraphic (fossil age) data,[4] as revised by the 2021 Hekkala et al. paleogenomics study using DNA extracted from the extinct Voay.[5]

Crocodylinae

Voay

Crocodylus

Crocodylus anthropophagus

Crocodylus thorbjarnarsoni

Crocodylus palaeindicus

Crocodylus Tirari Desert

Asia+Australia

Crocodylus johnstoni

Freshwater crocodile white background.jpg

Crocodylus novaeguineae New Guinea crocodile

Crocodylus mindorensis Philippine crocodile

Crocodylus porosus

Crocodylus porosus white background.jpg

Crocodylus siamensis Siamese crocodile

Siamese Crocodile white background.jpg

Crocodylus palustris

Mugger crocodile white background.jpg

Africa+New World

Crocodylus checchiai

Crocodylus falconensis

Crocodylus suchus West African crocodile

Crocodylus niloticus

Nile crocodile white background.jpg

New World

Crocodylus moreletii Morelet's crocodile

Crocodylus rhombifer

Cuban crocodile white background.jpg

Crocodylus intermedius Orinoco crocodile

Crocodylus acutus

American crocodile white background.jpg

Characteristics

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 to 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 to 9 ft 10 in) and a weight of 40 to 120 kg (88 to 265 lb) as an adult.[7][8] Three individuals ranging from 2.12 to 2.63 m (6 ft 11 in to 8 ft 8 in) in total length and weighing from 40 to 87 kg (88 to 192 lb) had bite force of 2,073–4,577 N (466–1,029 lbf).[9] Large male individuals reach 4 m (13 ft) and 350 kg (770 lb) in weight.[10]

Distribution and habitat

Siamese crocodiles occur in a wide range of freshwater habitats, including slow-moving

Behaviour and ecology

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

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]

Threats

Siamese crocodiles are under threat from human disturbance and habitat occupation, which is forcing remaining populations to the edges of their former range.

crocodile farms in Southeast Asia.[11]

In 1992, it was believed to be extremely close to or fully

Burma or Brunei. A small but important population of the crocodiles is also known to live in East Kalimantan
, Indonesia.

Habitat degradation

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.[20] 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.[citation needed
]

Many river systems, including those in protected areas, have

Mekong River and its major tributaries.[21] Potential impacts of dam construction include wetland loss and altered flooding cycle with a dry season flow 50% greater than under natural conditions.[22]

Exploitation and fragmentation

Tonle Sap
in Cambodia

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.[citation needed]

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.[23] In the late 1940s, populations spurred the development of farms and harvesting wild crocodiles for stocking these farms.[24] 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..."[23]

Crocodile farming now has a huge economic impact in the provinces surrounding Tonle Sap, where 396 farms held over 20,000 crocodiles in 1998.[23] Also, many crocodiles were exported from Cambodia since the mid-1980s to stock commercial farms in Thailand, Vietnam, and China.[25]

Despite legal protection, a profitable market exists for the capture and sale of crocodiles to farms since the early 1980s.[25] This chronic overharvesting has led to the decline of the wild Siamese crocodile.[citation needed]

Conservation

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]

The current situation of C. siamensis represents a significant improvement from the status reported in the 1992 Action Plan (effectively extinct in the wild), but poses major new challenges for quantitative survey and effective conservation action if the species is to survive. While the species remains critically endangered, there is a sufficient residual wild population, albeit severely fragmented across several areas and countries, to provide a basis for recovery.

The Siamese crocodile is relatively unthreatening to people (compared to

C. porosus
), and the possibility of people and crocodiles coexisting in natural settings seems possible. The powerful economic force of the commercial industry based on C. siamensis also needs to be mobilised and channelled for conservation advantage. Considerable effort and action is still required, but the species has a reasonable chance of survival if the necessary actions can be implemented.

Yayasan

Ulin (The Ironwood Foundation) is running a small project to conserve an important wetland habitat in the area of East Kalimantan which is known to contain the crocodiles.[26] Most of them, though, live in Cambodia, where isolated, small groups are present in several remote areas of the Cardamom Mountains, in the southwest of the country, and also in the Virachey National Park
, in the northeast of the country.

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.

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.[27]

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.

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.

Savannakhet Province, promotes conservation of biodiversity for the whole landscape, and relies on community involvement from local residents.[29]

In September 2021, eight hatchlings were found in a wildlife sanctuary in eastern Cambodia.[30]

Priority projects

High priority projects include:[31]

  • Status surveys and development of crocodile management and conservation programmes in Cambodia and Laos: These two countries appear to be the remaining stronghold of the species. Identifying key areas and populations, and obtaining quantitative estimates of population size as a precursor to initiating conservation programs is needed.
  • Implementation of protection of habitat and restocking in Thailand: Thailand has the best-organized protected-areas system, the largest source of farm-raised crocodiles for restocking, and the most-developed crocodile management programme in the region. Although the species has virtually disappeared from the wild, re-establishment of viable populations in protected areas is feasible.
  • Protection of crocodile populations in Vietnam: a combination of habitat protection and captive breeding could prevent loss of the species in Vietnam. A breeding population has been successfully re-established in Cát Tiên National Park. Further surveys, identification of suitable localities and the implementation of a conservation programme coordinated with the captive breeding efforts of Vietnamese institutions is needed.
  • Investigation of the taxonomy of the freshwater crocodiles in Southeast Asia and the Indo-Malaysian Archipelago: The relationships among the freshwater crocodiles in the Indo-Malaysian Archipelago are poorly understood. Clarification of these relationships is of scientific interest and has important implications for conservation.

Other projects include:

  • Coordination of captive breeding, trade and conservation in the South east Asian region: Several countries in the region are already deeply involved in captive breeding programs for commercial use. Integration of this activity with necessary conservation actions for the wild populations (including funding surveys and conservation) could be a powerful force for conservation. A long term aim could be the re-establishment of viable wild populations and their sustainable use by ranching.
  • Maintain a stock of pure C. siamensis in crocodile farms: The bulk of the captives worldwide are maintained in several farms in Thailand where extensive interbreeding with C. porosus has taken place. Hybrids are preferred for their superior commercial qualities, but the hybridisation threatens the genetic integrity of the most threatened species of crocodilians. Farms should be encouraged to segregate genetically pure Siamese crocodiles for conservation, in addition to the hybrids they are promoting for hide production.
  • Survey and protection of Siamese crocodiles in Indonesia: Verification of the presence of C. siamensis in Kalimantan and Java is a first step to developing protection for the species within the context of the developing crocodile management strategy in Indonesia.

Cultural references

A Malay folktale features a crocodile that is outwitted by a mouse-deer and buffaloes.[32] A Siamese crocodile has been cited in the Thai folklore of Central Thailand's Krai Thong ("ไกรทอง") tales have known as well,[33] and was taken to create a television series and movies several times.[34]

A Siamese crocodile stars as the titular monster in the 1978 Thailand film Crocodile.[35]

References

  1. PMID 34567843
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  2. ^ . Retrieved 22 January 2022.
  3. ^ a b Crocodilian Species List: (January 2009). "Crocodylus siamensis".
  4. PMID 30051855
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  5. .
  6. ^ a b Steel, R. (1989). Crocodiles. London.
  7. S2CID 26640928
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  8. ^ Whitaker, N. & Sivaraman, C. (2022). "Behavior in a captive family group of Siamese Crocodiles (Crocodylus siamensis) at the Madras Crocodile Bank Trust near Chennai, India". Reptiles & Amphibians. 29 (1): 71–75.
  9. PMID 22431965
    .
  10. ^ "Farmer raises 6000 crocs". Chinadaily.com.cn. 2012-07-10. Archived from the original on 2016-03-04.
  11. ^ a b c d e f Simpson, Boyd; Bezuijen (2010). "Siamese Crocodile Crocodylus Siamensis" (PDF). Crocodiles. Third Edition. Retrieved 2011-11-29.[permanent dead link]
  12. ^ a b c Ross, R.P. "Crocodiles: Status Survey and Conservation Action Plan" (Second ed.). Archived from the original on 2011-12-24. Retrieved 2011-11-29.
  13. ^ Alderton, D. (1991). Crocodiles and Alligators of the World. Blandford, London.
  14. .
  15. ^ CrocBITE, Worldwide Crocodilian Attack Database: Siamese crocodile, 15 June 2008. Charles Darwin University, Northern Territory, Australia.
  16. ^ CrocBITE, Worldwide Crocodilian Attack Database: Siamese crocodile, 15 July 2012. Charles Darwin University, Northern Territory, Australia.
  17. ^ CrocBITE, Worldwide Crocodilian Attack Database: Siamese crocodile, 1 January 2017. Charles Darwin University, Northern Territory, Australia.
  18. ^ CrocBITE, Worldwide Crocodilian Attack Database: Siamese crocodile, 15 June 1944. Charles Darwin University, Northern Territory, Australia.
  19. ^ CrocBITE, Worldwide Crocodilian Attack Database: Siamese crocodile, 1 January 1928. Charles Darwin University, Northern Territory, Australia.
  20. ^ Phiapalath, P.; Voladet, H. "Wetland Priority Sites in Lao PDR – the top five priority sites" (PDF). IUCN (Climate Change Impact and Vulnerability Assessment for the Wetlands of the Lower Mekong Basin for Adaptation Planning). Retrieved 2011-11-29.
  21. .
  22. ^ Lamberts, D (2001). "Tonle Sap fisheries: A Case Study on Floodplain Gillette Fisheries in Siam Reap Cambodia". RAP Publication. Bangkok: FAO Regional Office for Asia and the Pacific.
  23. ^ a b c Thuok; T. (1994). "Country report on crocodile conservation in Cambodia" (PDF). Crocodiles: Proceedings of the 12th Meeting of the Crocodile Specialist Group. IUCN Publications: 3–15.
  24. ^ Kimura, W (1969). "Crocodiles in Cambodia, Research Report No. 3 Atawgawa Tropical Garden and Alligator Farm". {{cite journal}}: Cite journal requires |journal= (help)
  25. ^ a b Thorbjarnarson, J (2001). "herpetology trip report: Cambodia. Report to Wildlife Conservation Society". {{cite journal}}: Cite journal requires |journal= (help)
  26. ^ PAC2013 (2009-07-05). "Siamese Crocodile Conservation Case Study | The Mohamed bin Zayed Species Conservation Fund". Speciesconservation.org. Retrieved 2016-12-15.
  27. ^ "Crocs thought to be extinct found in Cambodia". www.nbcnews.com. Retrieved 2022-08-04.
  28. ^ Endangered crocodiles hatched in Cambodia. The Associated Press via cbc.ca (June 10, 2010)
  29. ^ "WCS Helps Hatch Rare Siamese Crocodiles in Lao PDR". Retrieved 2011-12-01.
  30. ^ "Hatchlings of endangered crocodile species found in Cambodia". AP NEWS. 2021-09-21. Retrieved 2021-10-05.
  31. ^ Ross, James (1998). "Crocodiles: Status Survey and conservation Action Plan. Second Edition. IUCN/SSC Crocodile Specialist Group". Archived from the original on 2012-03-29. Retrieved 2011-11-29.
  32. ^ Winsedtt, R. V. (1906). "Some Mouse-deer Tales". Journal of the Straits Branch of the Royal Asiatic Society. 45: 61–69.
  33. ^ "ตำนานและนิทานพื้นบ้านจังหวัดพิจิตร เรื่องชาละวัน- ไกรทอง" (in Thai). ท่องเที่ยวพิจิตร. Retrieved 19 June 2016.
  34. ^ "เปิดตัว พญาชาละวัน จากเรื่องไกรทอง 2015 เวอร์ชั่นนี้แซ่บเว่อร์ !!". Kapook.com (in Thai). 28 September 2015. Retrieved 19 June 2016.
  35. Nation TV (in Thai). 8 November 2015. Archived from the original
    on 2020-02-16. Retrieved 19 June 2016.

External links