Egg Laying
Female pythons will generally shed their skins 3-6 weeks prior to oviposition. After sloughing, the snakes should be provided with a suitable egg-laying site. For the majority of pythons, a plastic container, perforated to allow air flow and partially filled with moist vermiculite or sphagnum moss is suited to this task. The container must obviously be large enough to allow the female to enter and leave the box as desired. The humidity within the container should be maintained at the correct humidity (see section under 'Incubation of Python Eggs' below), so as to encourage the female to lay in the box, and not, for instance, in the water bowl or on the vivarium substrate itself.

This clutch of eggs delivered seven healthy hatchlings following a 65 day incubation at 30°C (90°F).

Most commonly, however, keepers elect to artificially incubate the eggs in captivity. This obviously entails the removal of eggs from the female snake. This procedure should be carried out as soon after oviposition as is possible, with minimal trauma to the snake, the eggs, and, indeed, on occasion, the keeper! Removal of eggs can be relatively easily performed using the procedure described by Ross and Marzec (1990). Two people are required for this technique; more as the snake increases in size. The snake is first covered with two hands to try to prevent both damage to the eggs and one being bitten. The snake's head is then restrained and the coils of the animals carefully removed from the clutch of eggs by a second person. It is often helpful to wash the female in warm water and thoroughly clean and disinfect her vivarium after egg removal.

This will help to eliminate and odours of the clutch from the female and her enclosure, and aid in eliciting a subsequent feeding response. Other techniques for stimulating a feeding response in reluctant females include placing a freshly hatched set of egg shells and/or hatchlings into her enclosure.

Incubation of Python Eggs
If the eggs have been removed from the female, they can either be left in the egg-laying container, if suitable, or placed into a fresh container with appropriate incubation media. Vermiculite is most commonly used to incubate snake eggs, and the one recommended in this paper, although sphagnum moss, newspaper, paper towels and potting soil have all been used to some degree of success. The use of vermiculite requires prior mixing with the correct amount of water: for the majority of python eggs, the vermiculite should clump together when squeezed without the formation of drips. Exceptions do exist, however. For example, the Green tree python (Morelia viridis) and Jungle Carpet python (Morelia spilota cheynei) require a drier substrate than other pythons, whilst still maintaining high relative humidity (Ross and Marzec, 1990; Mattison 1998). If maternal incubation is opted for, it is imperative that the substrate upon which the female sits is relatively dry, as many pythons are susceptible to scale infections upon exposure to damp substrates (Ross and Marzec, 1990).

Python eggs require a temperature within a relatively narrow range compared to many other snakes during the incubation period. A constant temperature of 30-32°C generally will produce successful results. Eggs exposed to temperatures below the optimum, often results in increased numbers of stillborn young, whilst high temperatures are associated with dead and/or deformed young. The temperature can be provided by several types of heaters, such as ceramic heaters; the main requirement being reliability. A thermostat that is capable of maintaining a stable temperature within the egg clutch is essential for the successful incubation of python eggs. The wiring of two thermostats in series will help protect against thermostat failure as described by Ross and Marzec (1990), in addition to several products available from herpetological suppliers that are designed to warn of too high or too low temperatures.

In addition to the provision of adequate temperature, control of humidity is necessary in order to provide sufficient water for the developing embryos. A relative humidity of 75-100 % should be provided to the eggs throughout the incubation period. This can be maintained using misting with warm water, the placement of open water containers in the incubator/females enclosure, and using a substrate that will absorb water, such as vermiculite and sphagnum moss.

Hatching
Hatching of pythons can be estimated according to previously published incubation periods. Actual incubation periods will, however, depend on several variables; notably the temperature at which the eggs were held at during incubation. Table 1 displays several incubation periods for different species of python. From this data, several observations are worth noting. For several species of python, the incubation period is relatively constant, averaging around 60 days at 31-32°C. Such snakes include D'Albertis' python (Leiopython albertisii), Macklot's python (Liasis mackloti), Blood python (Python curtus spp.), Burmese python (Python molurus spp.) and Royal python (Python regius). However, certain pythons demonstrate marked variation in incubation periods; the Carpet python (Morelia spilota spp.), Green tree python (Morelia viridis) and Reticulated python (Python reticulatus) show large variations in this parameter. The intra-specific variations in incubation period may be related to several factors. For instance, the length of gestation will influence the incubation period, i.e. how well developed the embyros are at the point of oviposition. Sub-specific differences in reproduction may also affect the duration of incubation. As an example, the various subspecies of Carpet python display significant differences in the length of gestation and incubation period. Generally, however, both the gestation and incubation periods are constant for an individual snake when kept under relatively stable temperatures. Thus, once bred, a females reproductive pattern can be determined and used in subsequent breeding programs.

Baby pythons will typically wait in their eggs for 24-48 hours until they fully emerge. Emergence is usually accomplished at night.

It is necessary, of course, to provide the young with air, suitable heat (the same temperature as was used during the incubation period works well) and high relative humidity in addition to standing water. Hatchlings of many python species are susceptible to dehydration (Ross and Marzec, 1990); thus, high ambient humidity should be maintained at least until the first ecdysis.

Newborn pythons are often aggressive and should be segregated to prevent injury or death amongst siblings. Once separated and the first ecdysis has occurred, feeding trials can be commenced.

Species	Incubation Period (days)	Source
Children's python (Antaresia childreni)	42-59	2
Spotted python (Antaresia maculosa)	49-59	2
D'Albertis' python (Leiopython albertisii)	55-60	3
Macklot's python (Liasis mackloti)	59-62	1, 3
Carpet python (Morelia spilota spp.)	47-72	1, 2, 3
Green tree python (Morelia viridis)	38-65	1, 2
Blood python (Python curtus spp.)	58-65	1, 3
Burmese python (Python molurus spp.)	58-63	1
Royal python (Python regius)	56-65	1, 3
Reticulated python (Python reticulatus)	86-95	1

Key to sources:

1 - Ross and Marzec (1990).
2 - Barker and Barker (1994).
3 - Mattison (1998).

References

Barker, D.G. and Barker, T.M. Pythons of the world: Volume I, Australia. Advanced Vivarium Systems, Inc., California, USA, 1994, p. 171.

Mattison, C. Keeping and Breeding Snakes. Blandford, London, UK, revised edition, 1998, p. 224.

Ross, R.A. and Marzec, G. The reproductive husbandry of Pythons and Boas. Institute of Herpetological Research, California, USA, 1990, p. 270.