Green Tree Python

About the green tree python

The green tree python is a species of snake in the family Pythonidae, native to New Guinea, several islands in Indonesia, and the Cape York Peninsula in Australia. First described by German naturalist Hermann Schlegel in 1872, it was known for many years by the name Chondropython viridis before genetic analysis placed it within the genus Morelia, close to the rough-scaled python. As its common name suggests, it is a bright green snake, typically reaching a total length of 150 to 180 cm, though large females may reach 200 cm, with females slightly larger and heavier than males on average.

The snake has a relatively slim body with a long tail making up about 14% of its total length, and a large, angular head that is clearly set off from the neck. Its body is triangular in cross-section with a visible spine running along the back. Weight depends heavily on nutritional condition: males typically weigh 1,100 to 1,400 g, females up to 1,600 g, and especially large females can reach up to 2,200 g, though wild specimens tend to be considerably lighter than captive-bred snakes of the same length.

Genetic studies have found two distinct lineages within the species — a southern lineage spanning Australia, the Aru Islands, and southern New Guinea, and a northern lineage across northern New Guinea, the Vogelkop Peninsula, and Biak Island — which are thought to have diverged roughly 5 million years ago as New Guinea's central mountain range rose, even though the two groups look identical.

Behavior and diet

The green tree python is primarily arboreal, spending most of its time in trees, shrubs, and bushes, and only occasionally coming down to the ground. It has a distinctive resting posture, looping a coil or two of its body over a branch in a saddle shape and tucking its head into the middle of the loops — a habit it shares with the unrelated emerald tree boa of South America, and one that has led people to confuse the two species when seen outside their native ranges.

Its diet consists mostly of small mammals, particularly murid rodents, along with occasional reptiles such as geckos and skinks, and insects. Long-standing assumptions that the species also ate birds were tested by researcher Switak, who examined the stomach contents of more than 1,000 animals and found no evidence of avian prey. The snake hunts by anchoring itself to a branch with its prehensile tail, striking out from a coiled, S-shaped position, and constricting captured prey. Some wild individuals have been observed and photographed wrapped around the base of small tree trunks, facing downward in what appears to be an ambush position for ground-dwelling mammals.

The species is oviparous, laying clutches of one to 25 eggs. Breeding has never been documented in the wild, but in captivity females incubate and protect their eggs. Hatchlings emerge in a striking lemon-yellow color patterned with broken stripes and spots of purple and brown, or in golden or orange-red tones; young snakes from Iron Range National Park in Australia typically transition to adult green coloration over 5 to 10 days once they reach about 58 to 60 cm in length, at roughly one year old.

Range and habitat

The green tree python is found in eastern Indonesia — including Misool, Salawati, the Aru Islands, the Schouten Islands, and most of western New Guinea — in Papua New Guinea, including nearby islands from sea level up to 1,800 m elevation, and in Australia along the east coast of Queensland's Cape York Peninsula. Its preferred habitat is in or near rainforest, where it lives primarily in trees, shrubs, and bushes, only occasionally descending to the ground. In parts of its range it shares habitat and competes ecologically with the carpet python, Morelia spilota.

Conservation status

The green tree python is rated Least Concern (LC) on the IUCN Red List, a status assigned in 2010 based on its large range and only isolated population declines linked to smuggling. Despite this rating, illegal capture for the international pet trade remains a serious and monitored threat: an investigation across the Indonesian provinces of Maluku, West Papua, and Papua from 2009 to 2011 found that 80% of exported green tree pythons had been caught in the wild, estimated at around 5,337 individuals a year, with the heaviest harvesting concentrated on Biak and neighboring islands and resulting in local population declines. The species is listed on Appendix II of CITES, making international trade in wild-caught animals illegal, and it received full protection under Indonesian national law in 1999. Transport during smuggling is dangerous to the snakes, with up to half thought to die in the process. In the wild, the species faces predation from rufous owls, black butcherbirds, several species of hawk and goshawk, New Guinea harpy eagles, mangrove monitors, dingoes, and New Guinea quolls.