Emerald Tree Monitor

Class: Reptilia
Order: Squamata
Family: Varanidae
Genus and Species: Varanus prasinus
  • An emerald tree monitor lizard climbing on a branch with leaves
  • green tree monitor on a branch
  • An emerald tree monitor lizard climbing on a branch. The photo has a white background.
  • An emerald tree monitor lizard climbing on a branch. The photo has a black background.
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Emerald Tree Monitor

Emerald tree monitors are arboreal, prehensile-tailed lizards. They are dark jade to lime green with narrow, black cross-bands. These slender, arboreal lizards grow about 3 feet long, with tails twice the length of their body. 

Physical Description
The emerald tree monitor, or green tree monitor, is dark jade to lime green in coloration with narrow, black cross-bands along the body and tail. It uses its long claws and prehensile tail to grip tree branches when climbing. 
This slender lizard reaches a total length of approximately 3 feet (91 centimeters), with its tail about twice the length of its body.
Native Habitat
Green tree monitors are found on the island of New Guinea and several adjacent islands, in palm stands and rainforests with about 70 percent relative humidity.
Food/Eating Habits
These lizards eat large, tree-dwelling insects, as well as frogs, geckos, small mammals and birds. At the Smithsonian's National Zoo, emerald tree monitors are fed mice, insects and mealworms.
Social Structure
This species is one of the few that exhibits primitive social behavior. The lizards live in small groups made up of a dominant male, several females and a few other males and juveniles.
Reproduction and Development

Female green tree monitors reportedly use termite mounds as nesting chambers, because they serve as perfect incubators. Termites regulate the mound's temperature, providing ideal conditions. The termite mounds also offer protection from predators.

A tree monitor's clutch size is typically three to seven eggs, which have an incubation period of 164 to 165 days. Multiple clutches have been occasionally reported with females in human care. The young grow rapidly, increasing their weight by up to 400 percent during the first three months of life, and their length by 150 to 200 percent. Reproductive maturity is reached by age 2. There appears to be no difference in the age of sexual maturity between males and females, although young males tend to grow faster than females and attain greater overall size.

Emerald tree monitors are considered a species of least concern by the International Union for Conservation of Nature's Red List, as of a 2016 analysis. They are protected under Indonesian law and likely occur in protected reserves within their native range. The species appears to be adaptable and can survive on plantations or in modified habitats, as long as some trees and prey items are available.

These lizards have no significant threats in the wild and are present in the pet trade around the world but appear to be well-managed through captive breeding programs. Wild populations of green tree monitors are not presently exploited by the pet-trade practice, and it is unlikely that the rate of future collection would pose a significant threat to the species.

You Can Help

  • Be a responsible pet owner. Know where your pets come from, and avoid purchasing animals that have been taken from the wild. When bringing home a new pet, be sure to know what is required to keep it healthy. Consider if you are able to responsibly care for a pet for its entire life before choosing to bring it into your home. 
  • Buy sustainably certified palm oil products to support the sustainable growth and production of palm oil. 
  • Share what you love about emerald tree monitors with others. Simply raising awareness about this species can contribute to its overall protection.