As python breeders, we always look forward to the April/May period as it marks the end of all the hard work and preparation for the next breeding season. It also marks a time when we stop feeding our adult breeding animals and begin the cooling process for the coming winter and spring breeding programme. The emphasis shifts from the endless feeding and cleaning as you put weight on your breeding animals to observing their behaviour patterns as you plan your individual breeding activities.

In the last issue of Reptiles Australia, I covered the basics of python anatomy and reproductive processes. In this article, I am going to talk about some of the important factors in initiating these processes. Important factors to be considered include:- feeding regimes and the appropriate weight of your animals; the number of males and females you will be using; and what sort of temperature cycle are you going to adopt.

Temperature Cycling
Nearly any magazine article or book on breeding pythons that you care to pick up will discuss temperatures and temperature cycling. A lot of them simply seem to be repeating the same old information and rarely give much insight into exactly how it is done. The most often asked question I hear about breeding a species is “what temperatures do you use”.

There are basically two cooling methods that are employed to initiate breeding responses in snakes. The first is to hold the potential breeding stock at a more or less constant temperature suitable for feeding and keeping healthy animals, and then providing a cooling period for a few months while food is withheld before raising the temperature again. This style of breeding approach is probably most popular in the USA. It is a methodology that works with many of our Australian python species, for example from my experience most of our carpet pythons as well as other species like water and olive pythons will breed this way. In theory, the “flat cooling” approach can work at any time of the year, although it is obviously easier to perform with some regard to the natural seasons and the resultant impact of the weather conditions.

The second cooling method is to provide a more gradual reduction in day length and temperature so that the environmental regime more closely mimics the seasonal cycle snakes would be experiencing if they were in the wild. This can be achieved from its simplest form by keeping your snakes in the appropriate outside enclosures through to completely artificial control, and deliberate manipulation of, the snake’s environment.

We prefer to use the second gradual cooling method under tightly controlled conditions for three reasons. Firstly and most importantly, we have found that flat cooling does not give us the same success rate as the more gradual seasonal approach. Secondly, in each species we breed we have found over the years that mating, ovulation and laying occurs within a narrow window at the same time each year. This phenomenon aids our interpretation of behaviour and taking appropriate corrective action if required. And lastly, the laying and hatching process is spread over four months which is easier on the resources and our workload.

Because we live in South Australia with its seasonal extremes of temperature that are not suited to most python species, we maintain fairly tight control over the environment in our breeding rooms. At this juncture, I should say that there are a great many points of view on the subject of temperature cycling and as stated in the last article “there is no one right way to do it, just a hell of a lot of wrong ways”. With respect to this, all I can say is that the method I am about to describe below has now yielded us 100% success with all our woma, black-headed python, jungle carpet, inland carpet, Darwin carpet, Bredli, large-blotched pythons and Stimson pythons for at least the last five years.

The day/night cycle (shown in hours) we use for all our breeding stock is as follows:-

Our breeding rooms face north, so that as day breaks it shines through the window first, then the room light switches on and then the cage lights. In this way, the progression from dark to light and vice versa is more or less gradual. In my view, there is no absolute need to have in-cage lighting. We do this for a number of reasons, but there isn’t room to go into detail here. A similar effect can be achieved with a window and, if necessary, a lamp on a timer. The individual basking lamps in each of our cages is coupled with this same day/night cycle.

Temperature regimes are a more complex and a far more important issue than lighting. Firstly, you have the temperature gradient in the cage, the need for a periodic basking site (see Home Sweet Home - A Python's Perspective) and the diurnal as well as the seasonal cycle to consider. In our experience, each species differs somewhat in its requirements and some can be quite sensitive to even small changes. I will be discussing these nuances and the breeding of individual species in subsequent issues.

However, as a rule of thumb for the majority of our womas, black-headed pythons, carpets and Children’s pythons the following temperatures are a good guide. These temperatures represent the average room temperatures for each season with spring and autumn also showing the extent of the rise and fall in average temperatures over the period.

In reality, the influence of Mother Nature does affect our temperature regimes to some extent so that they bounce around these settings. This is shown by the attached graphs of our maximum and minimum temperatures through 2002 to 2005. The graphs also show the gradual nature of the temperature rise and fall in spring and autumn (see alongside this article).

The actual cage temperatures differ from these room temperatures because of the thermal properties of the cages and the additional heat from the basking sites. Again as a rule of thumb, to calculate ambient cage temperatures you need to add about 2 oC to the daytime maximums and 1oC to the night-time temperatures.

In the early days of my breeding experience, I found that the room temperature was as equally important as the actual cage temperatures. If the temperature differential between the room and the cage is too great, then the cage heating has to work too hard. If the room is mostly too warm then of course it is hard to lower temperatures sufficiently and to provide a basking site and a temperature gradient in the cage.

The number of cages in our main breeding facility generates enough heat through the day that no supplementary room heat is needed. At night, we control the fall in temperature by opening sliding ventilation panels to allow free air flow. In another of our breeding rooms, there are fewer cages and so we have to supply an oil heater connected to a timer and a thermostat to supplement the cage heating. The further south you live the more important it is to have some supplementary room heating to reduce the cage workload. Conversely, the further you live north the greater is the challenge to reduce room temperatures to cycle your animals effectively and so more room ventilation is needed.

As a final remark about temperature cycling, I should emphasise the importance of understanding the provenance of your animals when attempting to breed them. We have observed changing requirements when breeding black-headed pythons and carpets from significantly different latitudes. When breeding our Darwin carpets and black-headed pythons we found we needed to raise temperatures higher than those tabled above. We now breed them in a separate room which parallels these temperatures plus about 3-4 oC for both the seasonal maximums and minimums. So, if you have animals that originate from the far northern latitudes of Australia you would probably need to do the same.

Feeding Regimes
Because we cycle our animals through a winter period where night time lows can drop below 15 oC we do not feed any of our adult snakes from the end of April through to at least mid-September. In fact, we do not feed any of our breeding pairs until the female has laid her eggs (excluding Green pythons). I’m sure many can cite examples of snakes that continued to be fed year round and bred successfully. All I can say to this is that over the years we have adopted this practice because we found it improved our success rate markedly (and it gives us a break of five months from the relentless cleaning!). I have also seen snakes that have taken a rat at about the same time they “switch off” with disastrous results, as the rat sits in the stomach undigested.

During the feeding period, we offer small feeds to our breeding males every fortnight. We have found it best to keep them lean so as to keep them keen. Generally, overweight males tend to be less virile than slim ones (present company accepted). Using artificial incubation, which is less taxing on the females, we find that feeding our female breeders once a week is sufficient for them to put on weight in time for the next breeding season. Our experience is that if you wish to have consistent year-on-year success, it is very important that the females are not overweight. You should be able to clearly see the indentation along the backbone and when you hold a pre-breeding female easily feel her muscles rippling when she moves through your hands. A female that is blown up like a long thin balloon and feels like a bag filled with jelly is going to be reproductively challenged and probably not enjoy a long healthy life.

Breeding Stock and Male/Female Ratios
As another rule of thumb, we keep as many males as females in our breeding colonies. I know many buy one male and try to breed him with a number of females. This approach can be quite successful, but it has its risks and in my view is not the best strategy if you want to have a high level of continued success. Let’s face it, if you throw a pair of snakes in a bag in a cupboard and forget about them for 4 months you can get lucky and breed them – it doesn’t mean that this is the best method! The problem with having a low male to female ratio is that it increases the risk of failures. What if your prized male gets sick and your females are left wanting? What if an all important male decides to shed right at a crucial time and you can’t adequately cover your female(s)? Some species, like the womas and black-headed pythons, seem to be better stimulated into ovulation by having multiple partners. We find that our herpetocultural life is a little more certain with an extra male or two rather than too few.

In closing the second part of this series on breeding pythons, I will touch on two more controversial subjects and those are the compatibility of breeding pairs and male to male combat. I have found that once you have all the environmental and husbandry angles sorted out, any ripe male will mate with any ripe female, so this business of compatible pairs is largely a furphy. The occasional exception may occur when there is a large size difference between the pairs, or one animal is particularly aggressive and frightens the less aggressive individual into non-performance.

Although male to male combat has been shown to be effective at times, we do not use this technique. I have found that if all the conditions are right, there is absolutely no need to stir up a male breeder by using the presence or scent of another male. In fact, I would go as far as to say, if you have to resort to this approach you should consider what aspects of your husbandry are not quite right. I certainly do not need another male hanging around my mate and threatening me in order to be sexually active and it appears neither do my snakes!

With the breeding season nearly here, I would like to wish all of you hopeful reptile breeders the best of luck and may Mother Nature smile on you with many successful matings and then lots of happy little hatchings.