Black Tree Monitor

Children's Zoo


In the Zoo
3.5 feet
3.5 feet
1-2 pounds
Maturity is reached in 2 years.
Maturity is reached in 2 years.

Geographic Range

Found exclusively on the Aru Islands, off the coast of New Guinea.

Scientific Information

Scientific Name:
Varanus beccarii

Lifestyle and Lifespan

Activity Time Frame:
Sexual Dimorphism:
164-165 days
Lifespan in the Wild:
15 years
Lifespan in Captivity:
15 years




V. 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 curve slightly 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.

Species Specifics

While a relatively large lizard, the Black Tree Monitor is smaller than many other monitors. Their total length can reach up to 3-3.5 feet, with the tail making up 60-70% of the total length.The Black Tree Monitor is believed to be either a subspecies or a color variance of the Green Tree Monitor and therefore is very similar in appearance. Sexual dimorphism occurs with males being generally larger in size. They have larger heads and the base of the male's tail is more triangularly shaped. The base of the female's tail tends to be more roundly shape.

Physical Characteristics

This lizard is well adapted to an arboreal existence. It's prehensile tail is used as a very precise and dexterous extra limb. Its tail is particularly long, sometimes it makes up almost 2/3's of the reptile's body!



Found in lowland rainforests, palm forests, mangrove swamps and cocoa plantations. Seen only on trees and vines.


Habitats: Found mostly in the Eastern United States, Box Turtles occur as far north as Michigan and Maine, South to Florida, and as far West as Texas and Kansas. Found rarely above 1,000 feet in elevation, preferring low land habitats where water collects. Commonly associated with deciduous forests having high leaf litter and moisture these turtles are often located near rivers, streams, ponds, lakes and other bodies of fresh water, however, they are not good swimmers.


Carnivorous. Feeds mainly on insects and other small invertebrates, especially tree crickets. Will eat rodents. Will also feed on eggs and nestlings found in the treetops, as well as eating crabs and frogs.

Ecological Web

Secondary consumer. Relatively little is known about the ecology of this animal in the wild.

Activity and Behavior

Activity Pattern

Diurnal. Monitors are daytime lizards and spend most of their days living in treetops or swamps in search of food.


The gecko will lick its eye to clean it from dust and other particles.

Social Behavior

Solitary. 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. Black Tree Monitors in the wild are reported to be nervous and high-strung; they will flee if threatened, and if handled carelessly, will scratch, bite and then defecate on the offender.

Reproductive Behavior

Female lays 3-7 eggs, (often twice a year) that are incubated 164-165 days.


Hatchlings are about 20 cm (8 in.) long and weigh 8-10 grams. Black Tree Monitors, as the name suggests, are entirely black. However, hatchlings often possess a bright pattern consisting of rows of green or yellow spots which completely disappear within 12 weeks.



Not listed as endangered. (Listed as Data Deficient by IUCN.) But, it is vulnerable to loss of habitat due to the deforestation prevalent within its small, restricted range. It is also popular in the pet trade, with most specimens being captured from the wild, because they need so much room to breed in captivity.


Due to a widespread, consistent and persistent decline of the species, the ICUN considers the Box Turtle to be a Vulnerable Species. The decline is associated with anthropogenic causes, or manmade causes centering on urbanization. Agricultural use of pesticides within a shared water shed has negatively impacted young turtle survivability due to malformed eggs. Introduction of synanthopic predator species, (species who live near and benefit mutually from human settlement and urban habitats) such as ravens, coyotes and raccoons, are increasing in numbers as humans continue to urbanize.

Current Threats

Introduced Non-Native, Domestic, and Invasive Species

Our Role

No items found.

How You Can Help

Please be aware of the pets you choose to buy. Never get a pet that has been taken from the wild and never return a pet to the wild. Be aware of pesticide applications so as to not poison native animals that benefit your ecosystem. Finally, be conscious of your trash and waste so as to not attract unwanted animals such as ravens.

Fascinating Facts

Black Tree Monitors are born in various shades of green, but turn completely black as they reach adulthood.

Also referred to as Beccari's Monitor, or Aru Island Monitor.

Unlike other monitors, they do not use their tails as weapons.

They are nervous animals and usually hide amid the trees when humans are present.


Bennett, Daniel. Monitor Lizards: Natural History, Biology and Husbandry.

Grzimek, Bernhard. 1975. Grzimek's Animal Life Encyclopedia, Vol. 6. Van Nostrand Reinhold Co, NY.

Martin, Kristi. "Reptiles of Oakland Zoo" talk given January 23, 1999.

Mattison, Chris. Lizards of the World. 1989. Facts on File Inc.,New York, NY.

"Black Tree Monitor, Regenstein Small Mammal-Reptile House." Lincoln Park Zoo. On-line. Accessed March 7, 2017 at

"Black Tree Monitor." Buffalo Zoo. On-line. Accessed March 7, 2017 at

"Black Tree Monitor." The Big Zoo. On-line. Accessed March 7, 2017 at