Common Water Monitor

Adult, Photo: Gary Ades. Inset: juvenile, Photo: Eric Leung

Description: A giant among lizards, with a record length of 250 cm. Greyish or brownish in colour, with pairs of yellow ocelli forming faint bands across the body. Bands prominent in the young, but faded in old adults. Tail of juveniles with distinct yellow-black bands which fade in adults. Head large, rather flattened and elongate. Neck also elongate. Tongue long and forked. Scales bead-like. Tail long, muscular, laterally compressed; about half the total body length. Large, curved claws on all digits.

Habits and habitat: Lives mostly in low country, but almost nothing is known of the habits of native specimens. In Southeast Asia frequents the environs of rivers and lagoons: hence the name 'Water Monitor'. A very aggressive animal when aroused. Hisses loudly when annoyed, flickering its tongue and opening its mouth wide in threatening fashion. When cornered, lashes its tail sideways in self-defense against the intruder. This behaviour could be a way to stun large prey. Is an excellent climber, relying on its hook-like claws for support.

Diet: An indiscriminate carnivore. Eats mostly small mammals, fish, frogs, birds and their eggs. Occasionally raids farms, kills and eats chickens and other small livestock. Will eat carrion.

Reproduction: Lays about 10 large eggs in summer. Young about 30 cm at hatching.

Distribution: First recorded in Hong Kong during 1961-63 from Sha Tau Kok, Fanling, Stonecutters Island* and Cha Kwu Ling (one specimen per locality). Also reported from various localities in the 80s and 90s, but the specimens were most likely escapes or released animals. A very rare species locally; may be extinct in Hong Kong as optimal wetland habitats for this species have been destroyed. The Mai Po marshes, the best remaining area, have not yielded reports of this lizard for many years. Occurs in southern China, and from Sri Lanka eastward through Southeast Asia to Indonesia.

Diagnostic features: Elongate, flattened head; forked tongue; ocelli on the back; tail long, laterally flattened, muscular and banded; bead-like scales on body and limbs; long, arched talons.

*At the time of writing, this island no longer exists as such, as it has been joined to the mainland Kowloon by extensive reclamation work.