The Asian Water Monitor Lizard

The Asian Water Monitor Lizard : Varanus salvator

INTRODUCTION

This page tells the story of Varanus salvator, the Asian Water Monitor lizard, which today is one of the most readily accessible large reptiles on this planet - an animal which can be seen in many locations of southeast Asia where water is abundant. We look at the creature's life history, its habits and physical appearance.

This article refers specifically to the water monitors to be found in a large public park in Bangkok, Thailand, where they form a memorable and unusual tourist attraction.

All photos were taken by the author in Lumpini Park in Bangkok. Lumpini Park is also the subject of another web page by this author, which can be found in the links at the foot of this article.

The Asian Water Monitor

THE DRAGONS IN THE PARK

Lumpini Park in the capital metropolis of Thailand, the City of Bangkok, is a green and pleasant open space in the urban sprawl. The lungs of the city, Lumpini Park is a landscaped garden of ornamental flowering trees and carefully manicured and well watered lawns and flower beds. In the middle is an attractive boating lake with fountains. Bangkok residents and tourists alike will come to this park to relax away from the noises and smells of the city, to stroll along the walkways, to jog and exercise, or just to sit and contemplate and while away the hours. And because this is a haven of tranquility and beauty, the visitors expect to share their park with attractive flower beds and graceful butterflies and cute little squirrels and pretty song birds, and of course - enormous six foot long reptiles.

Six foot long reptiles??!!! Yes indeed. There are few places in the world where such outlandish modern day dragons can be found in close proximity to humans. But thankfully you don't need to be a modern day St George to survive here, and these dragons certainly don't need slaying. They are a species of monitor lizard, and they are indeed closely related to and quite similar in appearance to the infamous and lethal Komodo Dragon of Indonesia. But there the similarities end. Though theoretically capable of harming a very small child, in practice the lizards in Lumpini Park seem inoffensive and would much rather slip gently away into the water the moment a human being gets too close; I am not aware of any incidents of aggression being recorded in the park.

On hot days (in Bangkok that is most days!) monitors will bask in the sun

THE CLASSIFICATION OF VARANUS SALVATOR : THE ASIAN WATER MONITOR

All animals with backbones are included in the Phylum Chordata. The Chordata comprises five main living groupings or 'Classes'. These classes are the Fish, the Amphibia, the Birds, the Mammals, and the Reptilia, to which Varanus salvator belongs.

The Reptilia consists of four divisions or 'Orders' the members of which all share similar characteristics, and one of these orders is the Squamata which incorporates the snakes and lizards. Lizards belong to the Suborder Sauria, and monitors are to be found in the Family Varanidae.

THE BREEDING CYCLE

The breeding cycle of the Asian Water Monitor begins around April in regions with pronounced wet and dry seasons, and may continue until October. But in regions without a wet season, breeding may occur at any time of year. Each female produces up to 40 eggs per year, but usually these will be in two or more clutches laid in natural mounds such as termite hills, or in rotten or hollow tree trunks or in excavated burrows. Good, well protected sites may be communally used by several lizards. Usually the nest will be covered over after laying. Incubation takes several months though this can vary considerably according to the climate and the season of laying - an adaptability which has greatly assisted the lizard's widespread distribution throughout southeast Asia.

Hatchlings are about 30 cms (12 ins) long. Juvenile lizards are quite brightly coloured with yellow blotches against a darker background and yellow bands on the tail. These young monitors tend to be more timid than adults and hide away rather more. Usually it will take about 2 years to reach maturity, and adults can then live for about 15 years.

Varanus salvator is often to be seen at the water's edge .....

..... or just out of the water

FACTS ABOUT VARANUS SALVATOR

Varanus salvator is the most common species of monitor lizard to be found on the continent of Asia, occurring all through the southeast from India and Sri Lanka to Malaysia, Indonesia, Borneo and the Philippines - the widest range of any species. Water monitors can attain a length of 3m (10 ft), and a weight of more than 25kg (55 lb) making them genuinely alligator-sized creatures, and one of the very largest species of monitor after the Komodo Dragon. It must be said however, that the great majority including those in Lumpini Park are much smaller - between 1 and 2m (3 ft to 6 ft) in length.

The adult water monitor typically has a muscular brown-grey body with light patterning along the flank, and a pale underside. Patterning may vary within different subspecies. Water monitors have a characteristically long and narrow head and neck, and a long and laterally compressed tail.

This species V. salvator, should not be confused with the similarly named V. salvadorii - the crocodile monitor - a quite different species which lives in New Guinea.

The water monitor, as its name might suggest, is a powerful swimmer

LIFESTYLE

Most active in daylight, V. salvator tends to lead a solitary life, but these lizards are not particularly territorial. Usually the days are spent basking in the sun, or hiding away in burrows dug into river and lake banks. These burrows may be excavated deep into the ground and may be up to 9m (30 ft) long. However in Lumpini Park, the lizards make good use of artificial man-made burrows - the drainage water pipes which regulate the lake's supply of water.

Swimming, unsurprisingly, is the forte of the Asian Water Monitor, and with their powerful tail swayed side to side like a paddle and their legs tucked in along the side to streamline the body, these lizards are capable of traversing large bodies of water. This has enabled them to occupy many islands in the Indian Ocean, the Andaman Sea and the Indonesian archipelago. Typically their aquatic behaviour means that they are to be found along shorelines and mangrove coasts, but also in rivers and inland lakes. However these most adaptable of creatures are also at home on dry land, some distance from water, and at altitudes of up to 1,000 m (3,300 ft). They are also quite capable climbers - a versatility which undoubtedly helps in their success as a species.

Most species of Varanus are exclusively carnivorous, and Varanus salvator is no exception. It certainly isn't fussy about what it eats either. Anything it can cope with is fair game, including insects and snails, fish and frogs, birds and small mammals, and reptiles including young crocodiles. On land, their powerful leg muscles are used to chase and hunt down prey, and their climbing ability enables this species to raid birds nests too. But of course the monitors are equally adept at pursuing prey in their favoured aquatic habitat. And they will also scavenge when the opportunity arises, without too much concern over the freshness of the carrion.

In turn, the monitors may be hunted by larger crocodiles, and juveniles may be vulnerable to birds of prey and large water birds such as herons. In some rural localities they are also be used as a source of food by humans. To escape from predators a monitor can remain submerged for long periods of time (up to half an hour). But away from water it will run with alacrity, hide under vegetation, climb trees, or utilise the burrows and holes which are its preferred shelter on dry land.

There is something primordial about the appearance of these creatures

A CREATURE TO CHERISH

The status of the Water Monitor in the world today - like all animals - is impacted upon by the presence of man. Loss of habitat is of course a major problem. In some locations numbers have declined considerably through hunting for skins to be made into fashion goods. Potions are made too out of various body parts for sale in the far East as aphrodisiacs, skin ointments and medicinal tea. Roadkill is also a significant factor in lizard deaths.

However despite these negatives, this remains one of the region's most successful wild animal species. In some countries such as Thailand, the lizard is protected by law. In addition, high reproductive rates, the ability to rapidly spread and colonise new land though its swimming prowess, tolerance of different climates and the incredible adaptability of the species to a wide range of conditions and food supplies, have all contributed to its level of success. What's more, as we have seen, the monitor in safe environments has no problem living next door to man.

Varanus salvator in Lumpini Park, Bangkok, is a tame and a remarkably common creature. One only has to spend an hour wandering the edges of the ornamental lake to be sure of seeing a dozen or more. But Lumpini Park is not unique in this regard. In these days of sanitised living conditions in which humans live closeted lives and wildlife is kept strictly in its place, one usually has to travel very far, and sometimes to fenced off nature reserves, if one wishes to see the more impressive members of the animal kingdom. Therefore, although a giant lizard may not be a creature to love, it is certainly a creature to cherish as one of the most exotic of animals readily seen in tropical Asia. Anyone with an interest in wildlife should make the effort to seek out the water monitor. In Lumpini Park in Bangkok, it is easy to do this, but wherever one lives or visits in southern and eastern Asia, the Water Monitor is undoubtedly one of the wildlife sights to see.