A Green Tree Python! These arboreal snakes are born yellow or brick-red and turn bright green as they mature. Their vivid color, with a pattern of spots and stripes, provides a perfect camouflage. They can be virtually invisible in the tropical rainforests of New Guinea, eastern Indonesia and the northeast Cape York Peninsula of Australia. They have a prehensile tail (capable of grasping) that helps them climb trees and also plays a devilishly clever role in hunting.
They rest coiled horizontally on tree limbs forming a ‘ saddle’ pose with their head resting in the middle, which is also a good position to collect rain water. In the hunting position, the head is looking down ready to strike, and they often dangle and wiggle their worm-like tails to lure curious prey. This coiled position allows them to spring into action for a quick capture and instant immobilization of a tasty meal. These ambush predators are patient hunters, moving infrequently; in fact, to avoid being revealed, they typically only change positions during dusk or dawn.
Green Tree Pythons are non-venomous constrictors. Their one hundred teeth are backward-facing, and primarily keep the captured prey in place until it can be eased down into the digestive tract, because they swallow everything whole. They eat small mammals, rodents, frogs and other amphibians, birds, and other reptiles, like lizards, and though they’re capable of moving down from the trees to the ground, most of what they need comes to them and their wiggling “worm” high in the tree canopies. Juveniles are diurnal (active during the day) and hunt smaller animals. Adults are nocturnal and hunt larger mammals and reptiles, since they can open their mouths wider. Although they spend most of their time in the trees, Green Tree Pythons occasionally will come down to the base of a tree and use their sight and heat-sensing labial pits to locate an unlucky victim.
Green Tree Pythons have a seasonal breeding cycle; however, it is believed that they do not breed every year. The females prefer to nest in hollow trees and will have a clutch of about 5–35 eggs. Females protect and warm the eggs by wrapping around them with a ‘ muscular shiver’ to produce heat. Eggs hatch after about 50 days, normally in October or November. This coincides with the beginning of the wet season, ensuring that there will be ample food supply. About 12 inches in length when hatched, the baby pythons’ brick-red or yellow color is great camouflage and blends into the low-lying tree branches on the forest edge, where smaller animals reside. Here they can find lizards and small insects. The color change to the vivid green occurs between six and twelve months when the young python is about 22 inches long and is moving higher up the tree in search of larger prey. This “greening” is complete at about 2–3 years of age and these beautiful and resourceful pythons can grow to be about five feet in length.
If it looks like a Green Tree Python….
The Green Tree Python and the Emerald Tree Boa are examples of convergent evolution. Although they live on different continents and are not closely related, they look and act like each other and are found in similar habitats. Both live in tropical rainforests and consume diets that are alike. Both share the same resting and hunting positions. Both have red colored juveniles and both become bright green as adults. There are also significant differences, though. The Green Tree Python has finer scales and a more rounded nose. The Emerald Tree Boa has another row of heat pits above the mouth. The yellow color of the young Green Tree Python is never found in the Emerald Tree Boa, and The Green Tree Python is oviparous (lays eggs) while the Emerald Tree Boa is ovoviviparous (live births).
The green tree pythons are beneficial to their ecosystem by helping maintain a balance of rodents, birds and lizards. They also are food for several animals such as raptors, owls, dingoes and mangrove monitors. This species is at risk due to reptile enthusiasts collecting them for the pet trade, as well as loss of habitat due to logging. Fortunately, their IUCN conservation status, last assessed in 2017, is ‘least concern’ at this time. Let’s hope this doesn’t change.
Meet Diego and Frida
Reid Park Zoo has a pair of Green Tree Pythons. Diego and Frida moved to Tucson in 2008. They are contentedly housed in the Conservation Learning Center and are always on display, so you can safely get a really good look at them. It’s fun to visit and observe them closely — see if you can identify the “saddle position” or one of their tails looking deceptively wormlike — but remember, they want to be as still as possible in order not to tip you off! If you’re bringing children who might be afraid of snakes, you might enjoy reading ‘Verdi’ ahead of time. It’s a wonderful children’s book by Janelle Cannon, which explains the color change of a young Green Tree Python, as well as the challenges of life in the rainforest treetops.
It’s exciting to think of all the reptile relatives that will soon live nearby in the Reid Park Zoo expansion, but no matter what showy reptiles come to live in the Pathway to Asia, (like a Komodo Dragon!) Diego and Frida will still rank among the most beautiful creatures of their kind.