Green tree pythons (Morelia viridis) have a long history of captive reproduction, with more breeders now than ever. While challenges in egg incubation and newborn care have been overcome, this species is not considered easy to breed.
Healthy adult animals are essential for any breeding program. Females need sufficient body weight to handle egg production stress. Ultrasound tracking shows young females begin follicle development at 750-800 grams and should not be paired before reaching this weight, typically achieved at 3-4 years under normal captive conditions. Males can breed successfully at weights as low as 270 grams due to their smaller adult size. Temperature cycles effective for other boa and python species also work for green tree pythons. A nighttime drop to the low-70s Fahrenheit, combined with a daytime decrease of 2-4 degrees for four to eight weeks, stimulates reproductive interest in both sexes. Breeding introductions should start midway through this period and continue until the end. Pair animals during daylight hours to avoid accidental bites from feeding responses. Males usually court and copulate with properly conditioned females shortly after dark. Pairs may remain joined for several hours, sometimes until morning. After several weeks of copulation, females lose interest in food and may change color, often dulling or turning blue. Ovulation causes a large mid-body swelling resembling an overly large meal, lasting 12-24 hours, with the female appearing uncomfortable and restless. Careful observation is needed as some hide ovulation. Post-ovulation, watch for the female’s next shed, indicating egg deposition in two to three weeks. Once gravid, provide a comfortable egg deposition site like a nest box. Standard boxes are 8x8x12 inches, mounted mid-level in the enclosure, made of wood or plastic. Breeders use various nesting facilities, including lidded plastic buckets and overturned flower pots. Let hatchlings emerge from eggs at their own pace.Nest Box Setup
The nest box should have an entry hole or slot at least 2 to 3 inches in diameter. A layer of dry sphagnum moss, coconut fiber, vermiculite, or newspaper can be placed inside to help the female create a secure nest site and prevent eggs from sticking to the surface. Egg Laying Patterns Typical clutch size is 12 to 18 eggs, but clutches as large as 45 eggs have been observed. Captive green tree pythons may lay eggs year-round, with most eggs laid in spring and summer. In the wild, eggs typically hatch at the start of the wet season when neonate prey is abundant. Maternal Incubation Female green tree pythons maternally incubate their eggs for about 49-50 days. While natural, this method has drawbacks: females often stop feeding during gravidity, increasing stress and reducing reproductive capacity the following year. Monitoring egg condition is difficult, and one bad egg can spoil the entire clutch. Artificial Incubation Artificial incubation is now widely preferred. High-quality incubators are available at reasonable prices, or you can build your own. Sphagnum moss, vermiculite, and perlite are common incubation media, though many breeders now use a no-substrate method where eggs are suspended above water to maintain high humidity without direct moisture contact. Incubation Conditions Maintain the egg container temperature at 87-88°F throughout incubation; temperatures above 90°F can be lethal. Humidity should stay above 90%, with no direct moisture contact. Healthy eggs may dent or collapse slightly 10-14 days before hatching, with up to a 20% size reduction. Hatching Preparation Around day 49-50, replace water with damp paper towels to prevent drowning hatchlings. Add perches for the babies to rest after emerging. Once hatched, move them to individual containers.For hatchlings up to one year old, use tubs measuring 13 inches long by 8 inches wide by 4.5 inches high. Enclosure furnishings should include a few simple perch options, a water bowl, and a heat source.
Offer food after the snake’s first shed. Prey size should be approximately equal to the snake’s diameter at mid-body. The most successful method is tease-feeding using tweezers or forceps. Some neonates accept prey quickly, while others are shy, retiring, or quick to flee. Patience and finding what works best for each individual are key. Start with pre-killed or frozen-thawed pink mice. Prey motion technique is crucial to stimulate interest and initiate a feeding response. In the wild, neonates often begin feeding on small frogs and lizards, which exhibit short bursts of rapid movement. Replicating these movement patterns increases feeding interest. The first few meals are often the most challenging, but feeding becomes easier after several successful meals. Offer meals every five to seven days once feeding is established. For stubborn neonates that refuse unscented prey, try scenting with bird (day-old chick down or raw chicken skin—salmonella warning applies) or frog scents. Gently wash the pink mouse to remove its scent, then rub it on the desired scent item. Many neonates will accept the newly scented prey enthusiastically. Patience and persistence are pivotal, but remember that not every hatchling is meant to survive—some refuse food and cannot be saved.