Emerald Tree Monitor Fact File
This striking monitor species has a slender body which is covered with bright emerald green scales. These are streaked with black crossbars running across the body. On the underside their scales are white, yellow or a lighter shade of green. Under the throat some individuals have a yellow patch of scales. The bottoms of their feet are black. Each foot has long claws to help them hold trees when climbing.
The colouration of the emerald tree monitor is an adaptation that allows them to blend in with the trees in which they spend most of their time.
Their long thin tail is round in shape and is prehensile allowing them to hold on to things with their tail. This tail is the same length as their body.
An adult emerald tree monitor will measure between 75 and 100cm (30-39in). They weigh 300g (10.57oz). Males are typically slightly larger than females.
Captive animals have been seen eating small amounts of fruits and vegetables but they cannot digest cellulose and it is unlikely these are eaten in the wild.
Wild 14.2 years
Record 25 years
Emerald tree monitors are primarily found on the island of New Guinea within both the Indonesian and Papua New Guinea portions of the island. They can also be found on a range of smaller islands in the Torres Strait between Australia and New Guinea.
Various unconfirmed reports have been made from within Australia in the past but it is believed that these were all different species.
They can be found in rainforests, lagoons and swamps. As human habitations have expanded in to their range they have adapted to live in cocoa plantations.
Breeding takes place throughout the year and a female may lay up to three clutches throughout the course of the year.
Little is known of their mating behavior. Following a successful mating the female will deposit her clutch of two to four eggs in to a termite mound. The termites then seal the mound and this provides a suitable temperature for the incubation of the eggs.
This is similar to a behavior exhibited by the lace monitor in Australia. The lace monitor female returns to free the hatchlings once they hatch though it is has not been observed if this occurs in the emerald tree monitor.
Eggs are typically laid between June and November.
Incubation takes 160 to 190 days. Following hatching the young have food available straight away from the termites which are in the nest with them. After eating these they exit the termite mound.
Young emerald tree monitors grow quickly. After hatching they may grow 4 times as large within the first 3 months of their life.
They are sexually mature at 2 years old.
The emerald tree monitor is one of the few lizards which is social. Males and females will form small groups headed by a dominant male with many females.
They are primarily arboreal. Emerald tree monitors are well adapted for a life in the trees. Their prehensile tail acts like a fifth leg allowing them to easily hold on and move through the trees.
Predators and Threats
In most areas of their range they represent the apex predator and do not face any threats.
Humans affect their population in very small numbers through export for the pet trade. They can be bred in captivity and this should reduce the numbers caught from the wild.
They are a popular animal for display in zoos and to be kept as pets.
The emerald tree monitor is also known as the green tree monitor.
Used under license
Swanson, S. and Parish, S., 2011. Field Guide To Australian Reptiles. 2nd ed. New South Wales: Pascal Press.
Burnie, D., 2011. Animal. 3rd ed. London: DK
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<https://nationalzoo.si.edu/animals/emerald-tree-monitor> [Accessed 28 June 2020].
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