Description: The water monitor is a large species of monitor lizard. Breeding maturity is attained for males when they are a relatively modest 40 cm (16 in) long and weigh 1 kg (2.2 lb), and for females at 50 cm (20 in). However, they grow much larger throughout life, with males being larger than females. Adults rarely exceed 1.5–2 m (4 ft 11 in – 6 ft 7 in) in length, but the largest specimen on record, from Sri Lanka, measured 3.21 m (10.5 ft). A common mature weight of V. salvator can be 19.5 kg (43 lb).
They are the world's second-heaviest lizard, after the Komodo dragon. Their bodies are muscular, with long, powerful, laterally compressed tails. The scales in this species are keeled; scales found on top of the head have been noted to be larger than those located on the back. Water monitors are often defined by their dark brown or blackish coloration with yellow spots found on their underside - these yellow markings have a tendency to disappear gradually with age. This species is also denoted by the blackish band with yellow edges extending back from each eye. These monitors have very long necks and an elongated snout. They use their powerful jaws, serrated teeth and sharp claws for both predation and defense.
Habitat: The Asian water monitor is semiaquatic and opportunistic; it inhabits a variety of natural habitats though predominantly resides in primary forests and mangrove swamps. It has been noted that it is not deterred from living in areas of human disturbance. In fact, it has been known to adapt and thrive in agricultural areas as well as cities with canal systems, such as in Sri Lanka, where they are not hunted or persecuted. Habitats that are considered to be most important are mangrove vegetation, swamps, wetlands, and elevations below 1,000 m (3,300 ft). It does not thrive in habitats with extensive loss of natural vegetation and aquatic resources.
Range: Introduced into Florida with an established breeding population. The Asian water monitor is widely distributed from India, Bangladesh, Sri Lanka, Myanmar and Thailand, Cambodia, Laos, Vietnam, the Chinese Guangxi and Hainan provinces, Malaysia, Singapore to the Sunda islands Sumatra, Java, Bali, Borneo and Sulawesi. It inhabits primarily lowland freshwater and brackish wetlands. It has been recorded up to an elevation of 1,800 m (5,900 ft).
Diet: They are carnivores, and consume a wide range of prey. They are known to eat fish, frogs, rodents, birds, crabs, and snakes. They have also been known to eat turtles, as well as young crocodiles and crocodile eggs. Water monitors have been observed eating catfish in a fashion similar to a mammalian carnivore, tearing off chunks of meat with their sharp teeth while holding it with their front legs and then separating different parts of the fish for sequential consumption. The diet of the Asian water monitor in an urban area in central Thailand includes fish, crabs, Malayan snail-eating turtles (Malayemys macrocephala), Chinese edible frogs (Hoplobatrachus rugulosus), birds, small rodents, domestic cats (Felis catus) and dogs (Canis familiaris), chickens (Gallus gallus domesticus), food scraps and carcass. The stomachs of 20 adult Asian water monitors caught on Redang Island contained mostly human food waste, followed by turtle eggs and hatchlings, crabs and lizard eggs.
Venom: The possibility of venom in the genus Varanus is widely debated. Previously, venom was thought to be unique to Serpentes (snakes) and Heloderma (venomous lizards). The aftereffects of a Varanus bite were thought to be due to oral bacteria alone, but recent studies have shown venom glands are likely to be present in the mouths of several, if not all, of the species. The venom may be used as a defensive mechanism to fend off predators, to help digest food, to sustain oral hygiene, and possibly to help in capturing and killing prey.
Reproduction: The breeding season begins around the beginning of the wet season. Water Monitor Lizards breed rapidly. Larger females produce a larger clutch than smaller ones, up to 40 eggs a year in 2 or more clutches. Mating involves a lot of biting and scratching. Females lay their eggs 4 to 6 weeks after breeding. 3 to 25 white, soft-shelled eggs are laid, with an average of 15 per clutch. Eggs are laid in termite mounds (both active and abandoned mounds), along rotting logs or hollow stumps or in burrows. Eggs take 2.5-10 months or more to incubate.
Status: This species has a wide distribution, can be found in various habitats, and adapts to habitats disturbed by humans. It is still abundant in parts of its range, despite high levels of harvesting. Continuous and significant offtake levels over several decades may, however, have resulted in demographic changes the impacts of which on population viability are not understood. Significant taxonomic uncertainty still surrounds this species, and although this may not affect the extinction risk of Varanus salvator sensu stricto (which has a type locality on Sri Lanka, an area where subpopulations are at limited risk), this is of the utmost importance for identifying cryptic species which may be of more significant conservation concern. Subpopulations in Indochina and Myanmar are of particular concern and are likely to need at least local attention to control harvesting, as the lizard is exploited heavily throughout this area and is now often scarce, and declines are suspected or have been observed in much of this region. V. salvator does extend over an extensive geographic range and in some regions still is considered abundant and is consequently listed as globally Least Concern, but this species should be considered a conservation priority in areas where declines are ongoing or suspected and efforts are needed to determine the sustainability of high levels of offtake elsewhere in its range. Although the species is not at risk of global extinction at present, this status should be reviewed at regular intervals.
Subspecies:
Andaman Water Monitor - (Varanus salvator andamanensis)
Two-striped Water Monitor - (Varanus salvator bivittatus)
No Common Name- (Varanus salvator celebensis)
Southeast Asian Water Monitor - (Varanus salvator macromaculatus)
Sri Lankan Water Monitor - (Varanus salvator salvator)
Ziegler's Water Monitor - (Varanus salvator ziegleri)
Disclaimer: ITIS taxonomy is based on the latest scientific consensus available, and is provided as a general reference source for interested parties. However, it is not a legal authority for statutory or regulatory purposes. While every effort has been made to provide the most reliable and up-to-date information available, ultimate legal requirements with respect to species are contained in provisions of treaties to which the United States is a party, wildlife statutes, regulations, and any applicable notices that have been published in the Federal Register. For further information on U.S. legal requirements with respect to protected taxa, please contact the U.S. Fish and Wildlife Service.
){kind=link}
){kind=link}