A primeval predator


Biawaks evolved into amphibians about 100 million years ago.

MY first sighting of a biawak (monitor lizard) in 1999 happened by chance whilst watching hornbills roost along the Kinabatangan River in northeast Sabah.

Near to the river’s edge and upon the approach of human intruders, it quietly retreated into the rainforest.

My next view of this incredible creature was of a giant specimen in 2000, from one of 73 monitor lizard species, lumbering up the white sands of Police Beach on Pulau Gaya in the Tunku Abdul Rahman National Park off Kota Kinabalu.

More recently, it was my great pleasure to observe four of these hypnotic reptiles running at speed with several legs off the ground and tails violently swishing as they converged on kitchens serving day visitors’ lunches on Pulau Sapi, just across the shallow sea channel from Pulau Gaya.

After devouring scraps of meat thrown by kitchen staff, the monitor lizards searched out visitors’ food on the beach with saliva dripping from their mouths.

One naive visitor, despite warnings from local beach staff, tried to feed a monitor lizard with bare hands while her companions eagerly took photos of the event.

Little did she realise that the saliva and bite of a monitor lizard contains a dangerous toxic substance, not unlike that of the Komodo dragon, another type of monitor lizard.

Why the name monitor lizard? One explanation accounts for its ability to stand on its hind legs with its forked, snake-like, tongue protruding and swishing the air to sense its prey and that of its adversaries – crocodiles.

In the remoter upriver areas of Sabah and Sarawak, the local people maintain that a monitor lizard sends out a cry of warning of an approaching crocodile. In zoological terms, this reptile species is named Varanus, derived from the Arabic word for a lizard and from the Latin word ‘monere’ – to warn.

Basking in the midday sun seems to revitalise monitor lizards.

The species of monitor lizards that I have observed are the water monitors – Varanus salvator macromaculatus – found in Borneo, mainland Southeast Asia, Singapore, Sumatra and adjoining islands to all of these places.

This is the second largest lizard of the monitor species, to be dwarfed only by the Komodo dragon. With a two-metre length and weight of between 20kg and 50kg, their muscular frames and powerful tails are a sight to behold. Their long necks, sharp claws and many teeth are forceful features in entrapping their prey.

Swimming easily through water and relatively stealthy overland, they seem revitalised by basking in the midday sun with a sudden rush of energy.

Essentially these are carnivorous creatures feeding on crabs, fish, frogs, mice, rats and snakes as well as turtle eggs and baby crocodiles. At night they search out carrion.

Sometimes they work in pairs to secure an ambush of their prey as one lizard can tempt a female crocodile from her nest whilst another swoops in from behind to consume her eggs.

There is little research in the wild on the reproductive nature of water monitors apart from the details of their sexual reproductive lengths, which for males is 40 centimetres and females 16 centimetres.

We do, however, know that they tend to lay their eggs in the hollows between the buttress roots of tall species of trees and hide them using their sharp claws to scoop over the soil. As many as 30 eggs have been seen in a clutch.

Although the numbers of water monitor lizards are reckoned to be much the same as those of macaque monkeys in Malaysia, the monitor lizard population is slowly declining, partly because of their tendency to cross busy roads and also through hunting for lizard meat.

In some parts of Southeast Asia lizard tongues and livers are eaten as (scientifically unproven) aphrodisiacs. The fake ‘crocodile shoe’ industry readily uses the monitor lizard skins.

Undoubtedly the overseas trade in exporting very young monitor lizards to countries worldwide needs to be more strictly controlled. The Convention on International Trade in Endangered Species (Cites) states that the water monitor lizard is not, as yet, threatened by extinction.

These amazing predators evolved into amphibians about 100 million years ago yet they are slowly, like foxes in the UK, being driven into urban environments to scavenge in household rubbish bins.

Already in kampungs near riverside locations in Sabah and Sarawak, monitor lizards are known at night to devour chicken and small domestic animals.

Even 43 years ago, G Rothschild, an eminent member of the Department of Agriculture of Sarawak, in writing about ‘The Animals in Bako National Park’, in his concluding paragraph recorded that monitor lizards there “have become accustomed to prowling around dustbins and becoming tame and bold enough even to enter the kitchen by the back door”. A sweep of a broom would see them scuttling out.

Thank goodness their species has diminished in size from the enormous dimensions that roamed Borneo a million years ago.

Prehistoric our water monitor lizards may be, but our ‘water dragons’ must remain for us to see throughout this century and hopefully for future generations of both humans and monitor lizards.

Monitor lizards are slowly being driven into urban environments.