Black Tree Monitor

ORDER: Squamata

FAMILY: Varanidae

GENUS: Varanus

SPECIES: prasinus beccari

Prasinus is one of the prettiest monitors, with color varying from an intense turquoise green to black. The degree of black patterning varies with some specimens unmarked and others covered in a black reticulum. This subspecies is the totally black (melanistic) form. They may reach a total length of 100 cm (39 in.). This species of monitor is remarkable for its extreme slenderness and long narrow head and neck. Like all monitors, ear openings are evident, eyes have eyelids and round pupils and the jaws have powerful flattened teeth that curves lightly to the rear. The body is fairly massive with powerful legs, each having five clawed toes. Males tend to have larger heads and broader tails than females. The body is covered with various small, non-overlapping scales that form a granular pattern. The tail is usually twice the length of the body.

Found in lowland rain forests, palm forests, mangroves and cocoa plantations of New Guinea and the neighboring islands. Seen only on trees and vines.

Carnivorous. Feeds mainly on insects, especially tree crickets. Will eat rodents.

Diurnal. Nests in arboreal termite nests. Female lays three to seven eggs that are incubated 164-165 days. Hatchlings are about 20 cm (8 in.) long and weigh 8-10 grams. Maturity is reached in two years.

This lizard is well adapted to an arboreal existence. Its prehensile tail is used as a very precise and dexterous extra limb. The soles of the feet possess enlarged scales that may aid the lizard when climbing. Powerful legs allow it to run quickly. A monitor can detect very faint smells; its tongue is more highly adapted to detect scent than in any other lizard and as in snakes, the tongue has lost all function other than its sensory one. Eyesight is well developed to detect prey and avoid predators.

Although monitors are not social, neither are they territorial. Bipedal ritual combat has been observed in the trees during the breeding season. Since their tails are so important they defend their tails, rather than use them as whips. Hearing is not well developed and there is little vocalization. Monitors use their feet to walk, dig, climb and tear food apart.

The Black Tree Monitors can be found in the Wayne and Gladys Valley Children's Zoo.

Not listed as endangered.


  1. Bennett, Daniel. Monitor Lizards:Natural History, Biology and Husbandry.
  2. Grzimek, Bernhard. 1975. Grzimek
  3. Martin, Kristi. "Reptiles of Oakland Zoo" talk given January 23, 1999.
  4. Mattison, Chris. Lizards of the World. 1989. Facts on File Inc.,New York, NY.