General Breeding Information
Morelia viridis is a challenging and fulfilling species to reproduce in captivity. For an in-depth presentation of how-to breeding info, please order my book, The Complete Chondro. An overview of the fundamentals can be found below.
INTRODUCTION TO BREEDING
Few species of snakes being bred in captivity today evoke the passion and excitement as do Green Tree Pythons (Morelia viridis). Their highly variable colors and patterns, great beauty, fascinating offspring, and challenging breeding requirements, add up to make chondros one of the most sought after and addictive species. Most chondro owners find that they simply can't have just one! Actually, having a group of these animals is the rule for a good breeding project. Keeping just a single pair is a low percentage approach to successful breeding, and the odds of getting a fertile clutch go up dramatically when multiple pairs are set up to mate.
Chondro breeding is a major league study in patience. As you may conclude from reading this section, breeding the Green Tree Python is not for everybody. But if you have been infected with "chondro fever", conquering the challenges of breeding will add immeasurably to the satisfaction and enjoyment of keeping these beautiful and mysterious rain forest serpents.
There are several ways to determine the gender of your chondros. Everting the hemipenes of male neonates by applying pressure to the base of the tail is a common practice with many species of snakes. Due to the very fragile vertebrae of baby tree pythons, it is strongly recommended that this technique not be used on them, or in fact on chondros of any age. Probing, done by an experienced person using sexing probes made for this purpose, is a far safer way to sex your animals. Probing to determine the gender of chondros should be done only after the animals are a year old. Again, this will help avoid damage to the fragile vertebrae of young animals.
It may also be possible to determine the gender of yearling and older pythons by observing the body shape and feeding tendencies. Many males will begin to feed less aggressively, and will go off feed at times, beginning at eighteen months or so in age. Males often have more of a lean, slim body shape than the stout, stocky shape of most females, which also tend to grow larger. Of course, observing breeding behaviors is another way to sex chondros.
Mature male chondros will sometimes shed sperm plugs when they slough their skin. These are not shed hemipenes as is often claimed, but a brownish, dry string-like accumulation of dead sperm. The presence or absence (or size) of cloacal spurs is not a reliable indicator of gender, but the presence of sperm plugs is a safe sign of a male animal.
Some people feel frustration with the neonate non-sexing statements above, because they wish to purchase sexual pairs of animals for breeding. The best policy is to purchase a group of animals if the goal is to obtain a breeding colony. Just buying one pair, even a known sexual pair, is a low percentage method for those attempting breeding success. The steadfast avoidance of sexing neonates is something knowledgeable and responsible keepers and breeders accept as a part of working with these pythons.
In reality, getting chondros to copulate is the easiest part of the whole breeding process. GTPs can be bred through out the year provided the necessary environmental stimuli are provided. In a word, "change" seems to be the catalyst to inducing successful mating. For most breeders, this change is provided by dropping the night time temperature by ten to fifteen degrees F, after providing stable temperatures during the period prior to breeding. This temperature drop can be created by using natural temperature cycles where the keeper lives. I drop my cages down from a day time high of around 88 F to as low as 65 F at night. As long as the animals are warmed during the day, and have been properly conditioned prior to cycling, no health problems will be encountered. I cycle my breeders for four to six weeks before introducing them. Maintain this temperature regimen after the pairs begin to mate. I have had equal success regardless of which gender is placed in with the other. However, never place two males (or unsexed animals) together, as males can be territorial and may violently attack each other with serious injury often resulting.
I cycle my animals and leave them more or less together until I am sure that a successful breeding has taken place, or I determine that the pair are not compatible for breeding. Females developing egg follicles usually go off feed about 4-6 weeks prior to ovulation. I remove males once they lose interest in the female, normally about the same time she goes off feed. I restore nighttime heat for females once they ovulate, or if they are seeking heat and no longer being bred by the male.
RECOGNIZING GRAVID CHONDROS
Females produce follicles in their ovaries, which ripen and grow prior to ovulation and fertilization. Common symptoms associated with follicle development are loss of appetite, color and personality changes, and some swelling. This last symptom may or may not be clearly noticeable, depending on the size of the clutch. Females with ripening follicles tend to roll the coils slightly on the perch, was if exposing the eggs to overhead heat. Once females go off feed, turn pale or blue, and begin to swell, many breeders assume the female is gravid. In fact, females are technically not gravid until they ovulate. This event usually takes place about a month after swelling begins and food is refused.
A good ovulation produces a very noticeable mid-body swelling that appears suddenly, lasts for about 24-48 hours, and then disappears. Egg laying normally follows this swelling by about 40 days, but I have had females lay as long as 45 days after ovulation, and as early as 38 days. Shown below are photographs of females at the height of this 24 hour swelling. It is important to stop temperature cycles and provide the female with around the clock access to basking heat as soon as you observe ovulation, and to remove the male if you have not done so.
Ovulating females showing sudden localized swelling
NESTING AND EGG LAYING
Females will go through a pre-egg laying shed fourteen to twenty one days before the eggs are laid, with most clutches arriving on day 18 or 19. A nest box should be provided for gravid females once they have shed, and some may enjoy the security of one even sooner. I use wood nest boxes made of white pine, ten inches square, with a hinged lid, Plexiglas front, and a three inch access hole in one side. (See picture below.) The Plexiglas front is covered with dark paper except when viewing. I suspend the nest box in the top of the cage with an ambient temperature of about 82-85 F. Some breeders place the nest box on the floor. The best medium for the inside of the box is dry sphagnum moss, but whatever you use, it must be bone dry. Mist the cage, but not the inside of the nest box, to keep the humidity up until the eggs are laid. Females will normally enter the nest box soon after they shed, although some will not enter until a day or so before egg deposition. Some activity is normal, especially at night, but as egg laying time draws near the female should stay in the box.