4. Breeding Pythons – Part 1: The Basics.
...... by Doc Rock


So you want to breed pythons, do you? Some readers have probably had a go and found it is not as easy as first thought to achieve consistent and reliable results. You’ve no doubt tried reading everything you can find, but have discovered that there is no simple “how to do it manual” and the advice you receive is often jumbled and conflicting, or vague and too general. Certainly, that is how I found the hobby when I started, and judging from the many comments and questions we receive through our Southern Cross Reptiles website, this is the way many find it still.

The first point I would like to make about breeding reptiles is that there is no one right way to do it, just a hell of a lot of wrong ways. One of the greatest attractions of herpetoculture for me is that it seems no matter how much experience you gain there is always more to learn and surprises are just around the corner. So, while I cannot claim to know the right way, I do have many years of experience at getting things wrong and so hopefully can help point others in the right direction.

It is important to realise that breeding pythons with consistency is a year round project. You cannot just expect to put animals together and have them breed unless you have put in the necessary preparation and careful observation. When I first considered writing this series of articles, I started by writing down a list of the husbandry topics where I felt a basic understanding would be helpful when attempting to breed the various Australian python species. This list is as follows:

• Adult feeding regimes
• Temperature cycling
• Day/night cycles
• Mating schedules
• Using multiple males
• Male combat
• Male fertility
• Colony size – sex ratios
• Yolk formation
• Ovulation
• Determining pregnancy

• Pregnant snake nutrition
• Pre-lay care of females
• Nest box design
• Laying & egg collection
• Post-lay care of females
• Incubation techniques
• Managing the hatching process
• Post-hatch care of neonates
• Neonate Feeding
• Sex determination

Interestingly, when fielding frequent questions about how to breed a species, nearly two thirds of these topics are never raised by anyone and yet, from my experience, many can have a dramatic impact on results. Over the next series of articles, it is my intention to cover all of these subject areas at least briefly and so hopefully provide a basic yet comprehensive set of articles on the husbandry techniques for python breeding.

However, before embarking on this quest, it is probably best that I first describe in general terms the reproductive anatomy of pythons and the physiological processes they go through during the breeding cycle.

The sex organs, or gonads, of a male python are termed testes and produce sperm; the female gonads are called ovaries and they produce sex cells called oocytes. In both sexes, these organs are found in approximately the same area of the body. If you take a point a third of the body length from the base of the tail and then halve it, the area between these two points is approximately where you will find the gonads. In pythons, the right gonad is located further forward in the body than the left.

Sperm passes from the testes to the cloaca via a long thin tube called the vas deferens. In females it is the oviducts that provide passage for the eggs from the ovaries to the cloaca. When females are not reproductively active the oviducts are slender and straight (like the vas deferens in appearance), but when the female is reproductively active they are convoluted and thickened.

The cloaca is a pouch through which pass all the excretory and reproductive products. If you were able to look inside this pouch you would find three openings at the front of it. The lower one is the intestinal opening which has a horizontal flap of skin above it. Above this flap of skin are the paired genital openings. In both males and females, these openings are tightly closed, except when the female is in the process of laying her eggs.

At the rear of the cloaca are two backward facing openings which, unlike the other three openings previously described, have no sphincter muscle to close them. In male pythons, these openings house the two hemipenes either of which can be everted to mate with the female, depending on which side of the male she is lying. In female pythons, these openings look very similar to those of the male, but are shallower inside. Unlike the male, these structures cannot be turned inside out. By inserting a probe into these openings, the sex of a snake can be determined by measuring the depth of the pockets.

When the breeding season begins, and in response to certain environmental and physiological cues, the female will begin to produce yolk, a process called vitellogenesis. Yolk is a complex soup of proteins, phospholipids and fats and is produced outside of the ovaries. It is predominantly formed in the liver and then transported to the oocytes in the ovaries through the blood. During vitellogenesis, the oocytes grow enormously in size and are termed follicles.

The growth of the follicles uses a great deal of the female’s reserves and so it is paramount that she has sufficient condition before the breeding cycle begins. As the follicles become extended with yolk, the ovaries swell and so the lower portion of the female’s body swells noticeably. A common error I have seen with inexperienced breeders is that they mistake this swelling for the snake becoming gravid. Because of this misinterpretation they stop putting their male(s) with the female and end up disappointed. Often I hear the explanation that “for some reason she reabsorbed the eggs”. This is not true. There is no definitive scientific evidence anywhere I am aware of that pythons reabsorb eggs. Once the eggs have passed into the oviducts they are beyond the point of no return. No absorptive mechanisms have been found in oviducts. If the eggs are not successfully fertilized, they will eventually be passed as unfertilized ova, or what are commonly called slugs.

If you were to examine the ovaries of a python during the early part of vitellogenesis you would typically find oocytes at various stages of development and size. Vitellogenesis is completed once the oocytes have become mature, yolked follicles, all similar in size. It is my experience that python mating activity is greatest during early vitellogenesis and again just prior to ovulation. Often during the middle of this period mating interest and frequency drops right off. I have found this particularly true of our Uluru woma strain and each year it nearly gives me a heart attack with worry.

Once the follicles are mature and full-sized in the ovaries, they are released into the body cavity during the process of ovulation. While female pythons typically have synchronous ovulation (both ovaries release their follicles at the same time), this is not always the case. We sometimes see our pythons releasing the follicles from one ovary at a time so that it looks like they have ovulated twice. It is possible for us to determine when ovulation is occurring because it is accompanied by a mid-body swelling which can be so large that it looks like the snake has swallowed something a lot bigger than it should have!

This swelling is caused by the female pushing the ova (released from the ovarian follicles) forward in the body to form a tight mass. The female does this in order to manoeuvre the ova into each oviduct via the ostium, a funnel shaped opening into the anterior part of the oviduct called the infundibulum. These ostia are found in front of each ovary which is why the female pushes the ova forward to form the characteristic ovulation bulge. There is a dividing membrane in the middle of the snake which ensures that the ova from each ovary go to their respective oviducts. Once settled in the oviduct each ovum is now called an egg and is fertilized by waiting sperm and then shelled in its place in the oviduct. The whole process is fairly short-lived taking only 12 to 24 hours. In our experience it is most easily observed in womas and black-headed pythons and quite easy to miss in carpet pythons.

During the final stages of the breeding cycle, the female will normally shed about 20 to 35 days before she lays (depending on species and temperature). If she is happy and conditions are right, she starts laying by completely coiling her body in a circle with a space in the middle to take the forthcoming eggs. She places her head at the bottom of the space and then starts laying the eggs in a spiral formation. The eggs readily stick together to form a clump which can be cared for by the female until they hatch.

So, in a nutshell, that is what is happens when a python breeds. These days we have a 100% success rate with every female we try to breed (except for one variety of stimsons python #@%$^%) and because of this we are able to take orders from customers for snakes a year or more in advance of breeding them. However, there is no way we would have achieved this level of success without mentoring and advice from others.

Initially, I received a great deal of help from a herp in Adelaide called Rolly Burrell who showed me all the basics and took me from being a wishful novice to breeding a number of python species. Others contributed with their ideas like Simon Kortlang, Greg Fyfe, Dave Barker and Gavin Bedford.

This basic set of skills was then greatly enhanced by a person who I consider one of the greatest reptile breeders I have ever met, Peter Krauss. He took me under his wing and selflessly taught me his trade. Peter, who lives in the Atherton Tablelands, recorded the temperatures and humidities he used to breed his animals so that I could emulate them in Adelaide. He allowed me to visit and watch the way he prepared his females, mated and cared for them. He showed me his incubation techniques and answered my endless questions with no hope of ever being repaid in kind. Because of this, my breeding success increased dramatically and from this foundation I was able to develop my own personal style of keeping and breeding.

Every good breeder develops his own unique style. As I said earlier, there is no one right way to be successful. My style is meticulous, everything recorded and repetitive, like baking a cake. Peter Krauss works through enormous experience, a very great empathy for his animals and continual small adjustments from careful observation of his reptiles’ needs.

In closing, if there is one piece of advice I can offer over and above whatever insights I might be able to provide in this series on python breeding it is this - reading books and magazines and visiting all the websites and chat rooms can be a great help in improving your knowledge and skills, but nothing beats a great mentor who is willing to provide a guiding hand.

Photo 1 - Anatomy of a Female Snake

Photos 3 and 4 - During yolk formation the abdomen swells. Inexperienced breeders often mistake this swelling for the snake becoming gravid. The pictures above of a jungle carpet and a black-headed python show pronounced swelling from advanced follicle formation.
Photo 5 - This shows a woma python mid-ovulation.

Photo 6 - A black-headed python in a typical laying pose.
Photo 7 - A female Centralian Python wrapped around her clutch of eggs. The eggs readily stick together to form a clump which can be cared for by the female until they hatch.
Photos 8 & 9 - The final result of a successful breeding season which makes all the work and worry worthwhile - a clutch of black-headed pythons (above) and centralian pythons (below).