The Siamese crocodile (Crocodylus siamensis) is a small to 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.
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 an olive-green colour, with some variation to dark-green. Young specimens measure 1.2–1.5 m (3.9–4.9 ft) and weigh 6–12 kg (13–26 lb), growing up to 2.1 m (6.9 ft) and a weight of 40–70 kg (88–154 lb) as an adult. The largest female specimens can measure 3.2 m (10 ft) and weight 150 kg (330 lb). Large male specimens can reach 4 m (13 ft) and 350 kg (770 lb) in weight.[8] Most adults do not exceed 3 m (10 ft) in length, although hybrids in captivity can grow much larger.
Distribution and Habitat[]
The historic range of the Siamese crocodile included most of Southeast Asia. This species is now extinct in the wild or nearly extinct from most countries except Cambodia. Formerly it was found in Cambodia, Indonesia (Borneo and possibly Java), Laos, Malaysia, Thailand, Vietnam, Brunei, and Burma.
Biology and Behavior[]
Despite conservation concerns, many aspects of C. siamensis life history in the wild remain unknown, particularly regarding its reproductive biology. Adults feed mainly on fish and snakes, but also eat amphibians and small mammals.
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. 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. 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. Pure, unhybridised examples of this species are generally unaggressive towards humans, and unprovoked attacks are unknown.
Conservation Status and Threats[]
This crocodile is classified as critically endangered on the IUCN Red List, and is listed on Appendix I of CITES. It is one of the most endangered crocodiles in the wild, although it is extensively bred in captivity.
Threats[]
Siamese crocodiles are under threat from human disturbance and habitat occupation, which is forcing remaining populations to the edges of their former range. 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. Although few wild populations remain, more than 700,000 C. siamensis are held on commercial crocodile farms in Southeast Asia.
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. 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. In March 2005, conservationists found a nest containing juvenile Siamese crocodiles in the southern Lao province of Savannakhet. 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.
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. 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.
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. 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. Potential impacts of dam construction include wetland loss and altered flooding cycle with a dry season flow 50% greater than under natural conditions.