Black Tree Monitor

Varanus beccarii

A sleek, shiny black monitor lizard from Indonesia's Aru Islands that climbs with sharp claws and a grasping tail.

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About the Black Tree Monitor

Black tree monitors are 3 to 4 feet long, but most of that is tail, which can be two-thirds of their length. They are covered in shiny black scales and have long, sharp claws. They live in forests and mangrove swamps of the Aru Islands, off New Guinea in eastern Indonesia, mostly in the treetops. They eat small invertebrates, plus small mammals, frogs, baby birds and eggs.^[2]

Quick facts

Scientific name: Varanus beccarii^[2]
Size: 3 to 4 feet long, mostly tail.^[2]
Lifespan: Up to 15 years in the wild.^[2]
Diet: Carnivore. Mostly small invertebrates, plus small mammals, amphibians, baby birds and eggs.^[2]
Habitat: Forests and mangrove swamps.^[2]
Where it lives: The Aru Islands of eastern Indonesia.^[2]
Group life: Solitary. Active during the day.^[1]
Babies: 3 to 7 eggs, sometimes twice a year.^[2]
Conservation status: Data Deficient (IUCN Red List, assessed 2014).^[3]

Fun facts

A black tree monitor's tail can wrap around branches.^[1]
Its tail can be two-thirds of its length.^[2]
Rival males wrestle standing on their back legs.^[2]

Vocabulary

prehensile: Able to grab or wrap around things, like a tail that holds onto branches.
monitor lizard: A large, long-necked lizard with a forked tongue.
arboreal: Living mostly in trees.
pet trade: Buying and selling wild animals as pets.
data deficient: A conservation label meaning scientists don't have enough information to judge the risk.

See it in person

Oakland ZooOakland, California · Reptile and Amphibian Discovery RoomSee this animal on the zoo's website ↗

These zoos had this animal when we gathered our information, but animals sometimes move. Check the zoo's website or contact the zoo before you visit.

Sources

[1] Oakland Zoo. “Black Tree Monitor.” https://www.oaklandzoo.org/animals/black-tree-monitor/ (accessed 2026-10-02)
[2] Smithsonian's National Zoo & Conservation Biology Institute. “Black tree monitor.” https://nationalzoo.si.edu/animals/black-tree-monitor (accessed 2026-10-02)
[3] IUCN Red List of Threatened Species. “Varanus beccarii (Black Tree Monitor).” https://www.iucnredlist.org/species/42485677/42485686 (accessed 2026-10-02)