Water Monitor

(Varanus salvator)


Facts

Water Monitor IUCN LEAST CONCERN (LC)

 

Facts about this animal

With its total length of up to 3 meters, V. salvator is the second largest monitor lizard in the world. Only the Komodo Dragon (Varanus komodoensis) is bigger. However most water monitors are 1.5 meters long at most, whereby the tail is about 1 ½ the body-length. Also while the maximum weight of Varanus salvator can be over 50 kg, most are half that size. The have a long, slender, muscular body with a narrow, elongated head, a very long neck and well developed legs with long toes and claws. The tail is long and powerful, laterally compressed and has a dorsal keel. The scales on the top of the head are relatively large, whil those on the backand tail are smaller in size and are keeled. These are the characteristics of an amphibious animal, which swims well, also over big distances and can stay under water when diving up to 30 Minutes. Often they spend the night in the water. Water monitor are also good climbers, but one never finds them high up in the trees and when they feel threatened thex take refuge in the water. Their coloration is usually drab gray, dark brown or olive with yellow or white spots arranged in circles which give the appraeance of several stripes (bands) across their backs. Hence the German name “Bindenwaran”. The yellow is also scattered throughout the body. There are also yellow spots on the underpart of the animal. The belly is whitish with darker bands. Some individuals have a black temporal band edged with yellow that extends back from each eye. Coloration and markings vary not only between subspecies but also with age. Although not being territorial, water monitors are aggressive animals leading a solitary life. They use both their tail and jaw when fighting. Only when there is a large carrion several specimens can be seen feding at the same place. Usually they are active at daytime from the early morning until in the afternoon. They rest in hiding places often in trees but also under bushes, roots or fallen trees as well as in rock cavities, .Though also found on flat land, a typical burrow is in a river bank. The entrance starts on a downward slope but then increases forming a shallow pool of water. The average length is about 9.5 m, the average depth is about 2 m, and the average temperature is around 26 degrees Celsius. The Water Monitor is an extreme carnivore. This means that the lizard will eat about any animal that it believes it can consume. It has a greatly enhanced sense of smell and like a snake the it moves its tongue in and out transferring odors to a special organ called the vomernasal or Jacobson's organ, which is also found in snakes. Thus it finds its prey by smell. Some of the common prey includes: birds and their eggs, small mammals (especially rats, but also monkeys and squirrels), fish, lizards, frogs, snakes, crocodilian eggs and juvenile crocodiles, tortoises and sea-turtle eggs, crabs molluscs, insects, spiders, and carrion as well as scraps from human waste dumps. Like the Komodo Dragon, the water monitor has been known to dig up corpses of humans and devour them as well. Again, their diet varies betwen their area of distribution and age. Their breeding season begins in April and lasts until October, i.e. around the beginning of the wet season. However the testes of the male are the largest during April and the female is more receptive, thus there is an increase in reproductive success the earlier fertilization takes place. iI appears however that in areas without pronounced wet and dry seasons reproduction can take place at any time of the year. Mating in the water monitor is a rough affair involving a great deal of biting and scratching. If the female accepts the male, copulation is very short (about 1 ½ minutes). The water monitor is an very prolific animal. Large females can produce up to 40 eggs in a year. Eggs are usually laid in two or more clutches, often in termite mounds where these are available (both active and abandoned mounds are used), but they are also deposited in self made burrows well above the water level. When the eggs are laid the nest is mostly covered again. In some instances the females gather at the nests mounds of megapodes also known as incubator birds. These huge nests offer ideal conditions fort he development of the monitor eggs. Indeed up to 70 eggs have been found in one of these mounds, i.e. the eggs of four to seven monitor lizards.In these megapode nest mounds, but also in termite mounds there is a more or less constant temperature between 28 und 30°C and the young hatch after a period between app. 200 and 330 days. Incubation times however seem to differ widely depending upon the region, the period of laying the eggs, the climate and the nest site. The hatchlings are 25 to 40 cm long. Like all monitor lizards, they are extremely secretive and can be rarely seen, in spite of them being more brightly colored than the adults. Due to the elastic breeding cycles of the water monitor, in which eggs can be laid in any season and hatch at a speed determined by incubation conditions may ensure an even release of young monitors throughout the year.

Did you know?
Within the enormous range of this species a number of subspecies exist: V. s. salavtor (LAURENTDI 1768), V. s. andamanensis (DERENIYAGALA 1944), V. s. bivittatus (KUHL 1820), V. s. cumingi (MARTIN 1838), V. s. komaini (NUTHPAND 1987), V. s. marmoratus (WIEGMANN 1834), V. s. nuchalis (GÜNTHER 1872), V. s. togianus (PETERS 1872 Water monitors, as their name suggests, are rarely found far from water and they have no trouble swimming long distances. This ability has allowed them to colonize many remote islands. Once on these islands they have no trouble adapting as they, being carnivorous, will eat almost anything. Their diet depends mainly on their size. Indeed in some areas they fill the ecological niche commonly held by predatory carnivores. When females look for a place to lay their eggs, but also when digging a burrow and while egg laying their tail is carried high over their head. Perhaps this is a warning signal to conspecifics not to approach such a female and not to disturb her. Indeed other water monitors sem to keep their distance from fenales behaving in htis manner. But perhaps this behaviour is just a sign of excitation.


 

Factsheet
Class REPTILIA
Order SQUAMATA
Suborder SAURIA (AUTARCHOGLOSSA)
Family VARANIDAE
Name (Scientific) Varanus salvator
Name (English) Water Monitor
Name (French) Varan aquatique
Name (German) Bindenwaran
Name (Spanish) Varano acuático
CITES Status Appendix II
CMS Status Not listed

 

 

Photo Copyright by
Chris Huh

Distribution

 


Distribution
Range Bangladesh , Brunei Darussalam , Cambodia , China , Hong Kong, China , India , Indonesia , Lao People's Democratic Republic , Malaysia , Myanmar , Philippines , Singapore , Sri Lanka , Thailand , Viet Nam
Habitat V. salvator can be found in a wide range of habitats like forests, river deltas, river banks, swamps and beaches, in particular in mangrove forests, but also on farmland and grassland, always near or around bodies of fresh or sea water, like lakes, rivers and sea bays. Indeed the water monitor is a water-dependent species.
Wild population V. salvator is dependent upon habitats rich in vegetation. Habitat destruction due to illegal logging and/or the clearing of mangroves forests brings about not only the decline of the population but also its fragmentation. A further threat for water monitors is unsustainable hunting for their meat and their skin as well as for certain organs or their fat, which are used for medicinal purposes (e.g. in the Philippines and India). As for the meat, which tastes like chicken, it is a regular component of human food in its range, in fact the water monitor provides many millions of people with an important source of protein. Even immature eggs are eaten, as well as layed clutches (it is said that the eggs taste like those of sea. turtles) The skins are used for dietary protein, ceremonies, medicine, and leather goods. While in some areas it is still abundant and may be considered threatened n many other areas, however, the number of water monitors has declined significantly.Over most of mainland India and Bangladesh they have been exterminated. On the other hand, a number of feasibility studies have been undertaken to investigate the possibility of farming water monitors, but the fact that they still appear to be very common in many areas where they are regularly hunted suggests that such a programme may not yet be profitable.
Zoo population 65 reported to ISIS (2008)

In the Zoo

Water Monitor

 

How this animal should be transported

For air transport, Container Note 41 of the IATA Live Animals Regulations should be followed.

 

Find this animal on ZooLex

 

Photo Copyright by
Deror Avi

Why do zoos keep this animal

Only slightly smaller, but more colourful than the Komodo, the water monitor is a very attractive "dragon" which may be used as an excellent ambassador for the conservation of its south-east Asian habitats and their often threatened inhabitants.