7. Breeding Pythons – Part 4: Stress City.
...... by Doc Rock


It is now September and spring has sprung, so we are well into the python breeding season. Some species like olive, black-headed and woma pythons already should be gravid or close to it, while others like Jungles, Inland carpets, Centralian and Diamond pythons should be well advanced in their affections at least.

From now until December, it is stress city at Southern Cross Reptiles. It is the period when all the previous year’s hard work and preparation hopefully bears the fruit of gravid (i.e. pregnant) females and the bounty of lots of healthy eggs. For us, it is a time of intense observation and anxiety that expectations and promises will be met. If you haven’t bred pythons before, then you are probably wondering what all the stress is about. If you have had some experience, then you understand the serial worry about whether your female is gravid, if her eggs are healthy, about the incubation process and finally watching the babies slit the eggs and go through the trauma of hatching.

In previous articles, I talked about temperature cycling (Breeding Pythons - Part 2) and the mating process (Breeding Pythons - Part 3). Assuming this is all going well, the next most important issue is “how do I know when my female is gravid?” In my early days of breeding, like most novice breeders, I was never sure whether I had a gravid snake or not. Today, after caring for hundreds of breeding females, I find it difficult to understand why it was so hard to tell.

As explained in the previous articles in this series, the abdomens of female pythons swell up during the breeding season as follicles develop and remain that way after ovulation. But how do you know when unfertilized follicles, which were once in the ovaries, have been transformed into fertilized eggs that are now sitting in the snake’s oviducts? The answer is careful observation and knowing what to look for.

The first step is to be relaxed about handling your female python(s) through the mating period. Done carefully it should not cause any undue stress or problems for the keeper and the kept. I keep my females under close scrutiny when I feel ovulation is approaching, but I also try not to touch them more than a couple of times a week and I always provide lots of body support so organs, muscles and backs aren’t strained (I’m talking about the pregnant snake of course).

When you see that the back half of your female is becoming puffy and swollen, as you gently pick up the abdomen you should feel that it is quite soft and flexible (providing the snake is relaxed). In the final stages of development, the follicles rapidly expand and the female becomes a lot more sensitive to touch. Eventually, the moment she is touched she will curl her abdomen into a circle and hold it incredibly tense and hard. Any attempt to relax her and open the coil will be resisted. The snake remains in this state for at least a week as ovulation approaches and as she goes through the ovulation process. I have never had a snake that has displayed this behaviour that has not laid eggs and I have not come across a species or form of python that does not display the behaviour. After years of practice, all I do these days is gently pick up and hold the centre of the abdomen while the snake is still lying in its hide box, or stretched out basking and I know breeding will be successful. It is not hard to learn as I have showed other herps the technique and very quickly they can walk around our collection and tell which snakes are in the final stages of follicle development and ovulation.

It is common folk-law amongst herpetoculturalists that you can tell when a python is gravid, because it will often lie with its belly facing upwards. This is true, but many will lay belly up when all they have is developing follicles and the process of ovulation has not yet occurred. In my observation, this tendency and the timing of it varies between individual snakes and species. For example, Children pythons will often lie belly-up at the follicle stage, while womas tend to do it mostly in the latter stages of egg development. The reason pythons exhibit this belly-up behaviour is not well understood. Some say it is to help provide additional warmth to the developing eggs when the snakes bask. Personally, I think it is to ease the discomfort of pregnancy as females will do this when basking as well as lying in the coolness of their hide box.

Once your female python is gravid, she will start seeking more heat and increasing her basking time. It is important to watch carefully to determine the right amount of heat for her. If the female spends the whole day under the basking site, increase your heating. If she spends most of her time plastered against the glass front of the cage or hiding in the coolest corner, then reduce your heating. We pay a great deal of attention to pre-lay temperatures and have found that it definitely affects egg quality and the robustness of the resultant hatchlings.

After ovulation and the attendant tail curling behaviour described above, the next major sign that egg deposition is approaching occurs when the female has her pre-lay shed. Instances of females not shedding before laying eggs have been recorded, but in all the years we have been breeding snakes at Southern Cross Reptiles, we have never had a snake lay without shedding first. The number of days between the shedding and laying events varies between species. However, as a general rule I find that pre-lay shedding occurs around 20-30 days after ovulation and that egg deposition also takes place about 20-30 days after shedding. The timing not only varies considerably between individuals and species, but also with the temperature environment. Not surprisingly, the cooler the environment the longer the time for the eggs to develop and so the longer the female holds onto them before laying.

Another factor affecting the timing of egg laying is the gravid female’s satisfaction with her laying site. I have known females that are not happy with their nesting options to hold onto their eggs for extended periods and even become egg bound. Last year I inadvertently allowed the nest boxes of a couple of my womas to become completely dried out. I became aware of it because when checking their projected laying dates I noticed that they were behind schedule. The moment I fixed the humidity, both females immediately started moving their eggs down the abdomen towards the cloaca and then laid within 48 hours.

It is important to provide a hide box that is large enough for the female to lay a full clutch of eggs without compromising her laying position, or your ability to watch what is going on and to access the eggs if necessary. We place artificial turf on the bottoms of our nest boxes because eggs will not stick to it. We then place sphagnum moss across this to provide moisture. The females will usually move the moss into a pile around the sides of the box leaving the central laying area clear. We usually supply the sphagnum moss at about day 18-20 post pre-lay shed and then top it up with a bit of water as necessary to keep it damp. If you decide to try this technique, whatever you do don’t make the moss wet otherwise you will upset the female and possibly compromise the eggs. Also, the more humid the conditions you live in the less the requirement for any supplementary humidity. Living in South Australia, we are providing lots of spring heating in already dry conditions, so we have found it necessary to humidify nest boxes to get consistent, trouble free results.

The final signs exhibited by a gravid female python prior to egg deposition are restlessness and frequent writhing within her nest box. The writhing is caused by the female pushing against the sides and roof of the box with her coils to force the eggs down the oviducts towards the cloaca. This behaviour can be a real problem if the lid of your nest box is not secure. We have had black-headed and carpet pythons rip the lids off their boxes when you would have thought it an impossible feat. Whenever I watch our snakes going through this phase, it reminds me how glad I am to be a male and to have evolved to contribute more to the fun end of the breeding process.

Once a female has pushed her eggs down so that you see the first one is bulging up against the cloaca, you know laying is imminent. We find we can usually pick the night each of our snakes is going to lay. At this point, you are faced with a choice – do you allow the female to deposit all her eggs and make a clump, or do you try and harvest them individually? Both methods have their advantages and disadvantages. Our practice is to harvest olive, woma and black-headed python’s eggs separately and to allow water pythons, carpets and members of the children’s group of pythons to form adhesive clumps. The reasoning is that we find the former group produces more sensitive eggs and the latter have more robust eggs able to sustain the death of an egg within a clump without terminally affecting the surrounding eggs.

In general, we find that most pythons lay their eggs from midnight through to late morning. The process is exhausting for the snake and takes many hours. When the female has finished laying, if allowed by her keeper, she will gather up her eggs into a spherical or conical shaped pile where they adhere to each other for the rest of the incubation period. Often she will leave a few eggs outside of this clump. In the majority of cases, there will be something wrong with these eggs and they will die.

If you have decided to let the new mother produce a clump of eggs, the next step is to remove them. I never try to do this on my own. Pythons hold on tightly to their clutches and hook their tails up into the eggs from underneath. It is much easier to remove the eggs when one person holds the pointy end and the upper half of the body while the other unhooks the tail and winds the snake off the eggs. The eggs can then be swiftly moved into their incubation container which should have been kept somewhere so that its temperature is comparable to that of the newly laid eggs.

A female snake that has just lost her eggs is a stressed animal. In the early days of our breeding, it used to distress me watching the female desperately pace her cage looking for her lost eggs. Often, they would wrap around a piece of cage furniture and try and incubate it. A snake in this state will usually not eat for long periods of time either, which can jeopardize next season’s breeding program. Through experience, we have learnt how to minimize this problem. Having secured the eggs, we rub our females from head to tail with a wet, soapy cloth to wash off all the smell of the eggs and to drown their senses with the smell of mild perfume. Each female is then placed somewhere temporarily until we can wash and clean her cage from top to bottom so there is no remnant smell of her eggs remaining. Having done this, we find that nearly all females will quickly settle down and start eating again within a couple of days.

Egg incubation is a subject that books can be written about and certainly one which can not be dealt with adequately as part of this article. So, I can only give a quick summary here and save the intricacies of incubation for another article one day. There are no hard and fast rules with incubation. Like breeding, there is no absolute right way to do it, but certainly some wrong ways. The essential elements are substrate, moisture and temperature.

The most common incubation substrates are those developed for horticulture like vermiculite and perlite. Recently, another technique called the “no substrate” method has become more popular where eggs are placed in some form of dry container that is suspended above free water to provide the necessary humidity. We use versions of all these methods with different species and even at different times during the incubation of a single clutch of eggs.

In my view for someone learning to breed pythons, the easiest incubation method is to use a vermiculite/water mix. For snakes like carpets and water pythons, we generally use a 50/50 mix, which means that 50% of the weight of the mix is made up of vermiculite and 50% is made up of water. In species like black-headed pythons, olives, womas and Children’s pythons, whose eggs are more sensitive to moisture, we use a drier 60/40 vermiculite mix, or alternatively we use a 50/50 perlite mix, as perlite holds a lot less moisture than vermiculite.

The surrounding hydric conditions (substrate humidity and air humidity) have an enormous effect on the development of python eggs. When eggs are first placed in their incubation containers, they absorb water and swell depending on the nature of the substrate, its wetness and the surrounding humidity. Excess moisture will cause an egg to swell too much and die, and too little will cause it to become dehydrated and die. Studies have shown that moisture affects the rate of metabolism of eggs, the length of incubation, the final reserves left in the yolk sac and the resultant size and health of the hatchlings. As a general guide, we provide a depth of substrate that is at least the equivalent thickness of the eggs being incubated in a sealed container that is 2.5 to 3 times the total volume of the eggs being incubated. The eggs are buried into the substrate so that at least 1/2 to 2/3 of the lower eggs (if in a clump) are exposed to the air. From experience, we have learnt that the best results are achieved by allowing the substrate to dry a bit as hatching time approaches. This seems to stimulate the absorption of yolk and the hatching process, so that lots of healthy babies emerge together.

Temperature is the third critical factor when incubating python eggs. Pythons are unique among snakes because they turn “warm blooded” when they lay eggs and then incubate them a bit like a bird. The female generates the necessary heat by shivering, or twitching her skeletal muscle. It is remarkable to watch a female wrapped around her eggs so that they are completely covered by a living wall of muscle through which every few seconds a tremor passes to keep the contents warm.

Studies have been done on wild pythons using fine electrical equipment to measure natural incubation temperatures. In a nutshell, the incubation environment for all Australian python species should be kept in the range of 30-32 oC. Having experimented with temperature over many years and with hundreds of clutches, I have come to the conclusion that the lower to middle end of this range works best for us. These days we do not tend to worry about incubation temperature as much as we do incubation period. For example, we have found that we get lower rates of egg death and healthier babies when our carpet pythons take between 55 and 58 days to hatch. Consequently, we tweak our temperatures in each incubator to achieve these incubation periods.

The climax of the breeding season is the appearance of all the little python heads poking out of their now crumpled white eggs. No matter how many times I watch it happen it still gives me a great buzz. Like all reptiles, pythons open their eggs using an egg tooth to slit the leathery shell. This process is exhausting and when it goes wrong can easily cause the death of a baby python. To reduce this risk, we always open our eggs with a pair of fine, sharp scissors within 24 hours of the first hatchling head appearing. The babes will usually sit inside their opened egg for one to two days while they adapt to breathing air and absorb their yolk sacs into their abdomens, finally leaving a tell tale “belly button” to show the spot. If you are using vermiculite or perlite as your incubation substrate, you need to watch out that the hatchlings don’t get covered with it and suffocate as they hatch and crawl around. At this stage, we often lift the eggs and place a folded sheet of newspaper under them to stop the problem occurring.

Once the babies have left their eggs and are starting to crawl around the incubation container, it is time to harvest them and place them in their individual new homes. We use a range of appropriately sized plastic boxes with a water bowl at one end and a little hide box (e.g. cardboard toilet roll) at the other. These boxes are placed half on a heat mat which is held at about 32 oC in a room that varies from 24-29 oC over the day night cycle. Baby pythons are prone to dehydrating in the first couple of weeks of their life, so we make sure they are kept humid by spraying their boxes lightly with a misting bottle. About 7-14 days after hatching they will usually shed their “egg” skin and reveal their true colours underneath. Then the real fun starts, because now you have to get them all feeding, pooping and growing well. But, that will be the subject of further articles when I start to look at individual species and all their specific requirements and quirks.....

As a female python approaches ovulation she becomes very sensitive to touch. Eventually, the moment she is touched she will curl her abdomen into a circle and hold it incredibly tense and hard. Any attempt to relax her and open the coil will be resisted. The pictures above demonstrate this characteristic in species as diverse as jungle and woma pythons.
It is common folk-law that you can tell a python is gravid because it will often lie with its belly facing upwards. The black-headed and woma pythons shown above were gravid, while the Stimson python was not.
The final signs exhibited by a gravid female python prior to egg deposition are restlessness and frequent writhing within her nest box. This Normanton stimson was caught in the act when the lid of her hide box was removed.
Pythons are unique among snakes because they turn “warm blooded” when they lay eggs and then incubate them a bit like a bird. Here a female Darwin carpet python wraps around her eggs so that they are covered by a living wall of muscle through which every few seconds a muscle tremor passes to keep the contents warm.
The same clutch of eggs again with the Darwin carpet removed to show the way pythons gather their eggs into a spherical or conical shaped pile. Notice how she has used the sphagnum moss we place on artificial turf to make a nest for her eggs.
Again the same clutch of Darwin eggs placed on vermiculite in a plastic incubation container.
We use perlite to incubate woma eggs because of their sensitivity to excessive moisture. The smaller egg was unfertilized and soon died.
All the hard work and worry becomes worthwhile when little python heads poke through the eggs. Here you can see the slits in the shells made by the egg teeth of these hatchling olive pythons.
Hatching time can be full of surprises. This picture shows twin spotted pythons emerging from their shared egg.