Incubation Strategies

By Francois Le Berre


Le Berre, F. (2003). Incubation Strategies. Chameleons! Online E-Zine, July 2003. (


I like to think of eggs as seeds. Little oval objects, left to the care of the ground and the environment harboring an invisible power of germinating life when conditions are favorable. Hatching chameleon eggs may seem to be a tricky affair. It is quite obvious that in a natural environment, eggs are subjected to all sorts of contacts with gases, minerals, liquids, radiations (think of heat or the absence of it), but also vegetal and animals if one thinks of the tiny insects or bacteria that may come to prey on them. It is generally admitted that the physical contacts from the environment are playing a necessary role in the chronological development of the embryos inside the eggs. Hormonal changes inside the eggs are forced by external forces and ensure the correct development of the babies. I am a firm believer that there is more in life than the eye can meet, but that attention has to be given to the little clues we might find on our path as well. So, are there any "tricks" to correctly hatching the eggs? Well, I am not sure on what to say next to a question like this one, I would prefer to refer to "Nature's secrets" rather than "tricks". All we can do when we work with animals is to learn as much as we possibly can in their company. If we are attentive enough, they will speak volumes to us. There is surely a lot more to learn on eggs and their incubation techniques. Meanwhile, I am glad to share with you some of my observations and a few techniques.

If you have been keeping various species of chameleons, you may have already noticed that some species go into some serious digging to lay their eggs whereas other species simply lay them on the ground (Brookesia spp., Rampholeon spp., C. boettgeri), glue them on a rock or stump (Br. perarmata), deposit them under a pile of dead leaves, at best in a shallow tunnel (Rampholeon spp., C. cristatus). Whereas the eggs of the Brookesinae and those of tiny Malagasy chameleons, such as the ones of the C. nasutus group, take a usual 2 months to hatch, those of C. oweni take an average of 7 months, whereas in the same region C. cristatus take up to 9 months whilst other might go as far as 18 months (C. parsonii and the likes).

Therefore, I like to consider 3 types of incubations: "short tropical incubations", such as the ones for the Brookesinae, some Rampholeon and some species of chameleons such as C. nasutus or C. boettgeri, "long tropical incubations" for most of the Chamaeleonidae, and "equatorial incubations" for mountainous and equatorial rain forest species.

It has been understood for a long time already that humidity and temperature were the two major factors affecting the development of chameleon eggs, both have to fluctuate with characteristic patterns in order to ensure the correctness of the hatching. Both the short tropical incubations and the equatorial incubation admit very little fluctuation whatsoever in temperature and humidity. Long tropical incubations on the other end, require specific concerted fluctuations in order to trigger and ensure proper embryonic development of the eggs.

The easiest eggs to hatch are those requiring little care, stable relative humidity and temperature, like the ones of the small chameleon species. Due to their small size, these chameleons usually lay only a couple of eggs, usually twice a year for tropical species, 2 to 3 months apart - at the beginning and near the end of the rainy season. Equatorial species are not bound to seasonal cues and therefore may lay eggs at any given moment of their reproduction life.

Short incubation times

Short incubations are due to the fact that most of the eggs are laid with well developed embryos. In some tropical species such as Brookesia perarmata, eggs are laid in the very early morning, preferably under a stump or wood. They appear to be very translucent and sticky to the touch at first, then the shell hardens and becomes opaque within 20 minutes after having been laid, in a very similar way to gecko eggs.

The peculiarity of the Br. perarmata's environment is that one may not see any water there but water is actually very present, underneath the surface, in crevices, in the soil, plants, etc.

Most "short incubation eggs" do good at temperatures in the low to medium 70's. Somehow, the eggs have to be left in contact with a moist surface, such as rotten leaves, slightly humidified coconut chunks / grind, moss, and the likes, and covered with a drier element such as bark or wood. Too much water surrounding the eggs will just cause them to burst prematurely or will drown the embryos, whereas too high temperature will be the cause of stillborns and deformities. Eggs can be deposited in a shoe box with no holes but with ample air to ensure proper gas exchanges within the box, and checked on a weekly basis. When temperature and substrate humidity are stable, hatching is eventless.

For lowland equatorial species of chameleons, the incubation technique and setup are similar, except the eggs are usually deposited by some female chameleon inside the ground and the process takes longer, which might raise the possibility of troubles.

For those who like to keep their eggs in a "natural way", the use of cleaned, sterilized earth material kept warm and humid for some time might not be good enough. They soon enough discover an amount of wiggling life forms they would never have imagined could have made it up to their incubating boxes: worms, springtails, ants, nematodes, etc. which are common sights whilst trying to incubate the eggs in natural substrate. These little creatures once established, start to thrive in their new home, where they also go on looking for food sources. It does not take them very long to figure out how to ruin a clutch of chameleon eggs. This is why most people use inert substrates such as vermiculite or perlite to deposit and hatch their eggs on the surface. It is a safe bet to incubate eggs of lowland equatorial chameleons on vermiculite, whether singly or touching on each other, but those looking for a "natural" overall incubation should try to pick up a naturally slightly acidic soil. Under temperate climates, one may prepare a blend of peat moss, oak leaves, dead rhododendron leaves, dried fern leaves that work very well when kept with the proper ambient temperature. Check the PH stays between 5 to 5.5 as a low PH medium does not favor the establishment of pests and germs, and keep the eggs as you see fit.

Since the humidity has to remain pretty constant, I use hermetic lids to hold the humidity inside the boxes. The room temperature (72 to 74 degrees F, 22 to 24 degrees C.) ensures a minimum of water condensation in the box keeping the relative humidity of the "incubator" at an even proportion throughout.

Incubating the eggs of equatorial mountain species

Equatorial mountain species have generally medium incubating times. They hatch on average in 4 to 7 months (C. johnstonii, C. melleri, C. quadricornis), with 5-6 months being the norm (C. montium), and the exceptions (B. xenorhinus, C. cristatus: 8-9 months). The mountain species experience heavy rainfall almost year round, but the soil in which they lay their eggs is usually very well drained. I had excellent results using volcanic soil for the incubation of various chameleon eggs of Equatorial mountainous species. A piece of equipment that I have found paramount to the success of my incubations was the use of a "cool incubator". I make a cool incubator with a Styrofoam box as the recipient, using its lid to insert a thermo electronic heat sink. The system is simple but the technology is tricky if you want a stable and guaranteed performance. Basically, a thermo electronic heat sink "sucks" the heat off the inside of the box and releases it outside the box. The great thing about thermo electronic sinks is that they can be put in any kind of position, and they are extremely accurate in the temperature gradient you choose and the heat sink can be inverted when the polarity is reverted (you can warm the inside of the box as well). We are all more of less familiar with the temperatures at which to incubate the eggs of most of the Equatorial mountain species. For most of the equatorial mountain species, night time temps of 65 degrees F (18 C) and day time temps of 72 F (22 C) are ideal. Ugandan / Zairean and some Tanzanian species take lower temps at night time, (50 F - 15 C). Ugandan chameleon eggs seem to hatch better with temperatures 20 to 40% cooler than the eggs of Cameroonian and Tanzanian species. Best results are obtained with night and day temperature fluctuations.

Incubating the eggs of tropical species

Chameleons dig in the soil so as to lay their eggs do so to ensure they would be in contact with the proper amount of humidity to develop. As a rule of thumb, species digging deep and laying a lot of eggs are usually species experiencing the most dramatic climatic fluctuations in their environments, with sometimes the longest incubation periods.

Under tropical (not equatorial) climates, chameleons are most likely to lay their eggs right after the rainy season. When the rainy season has been abundant, the food should have been plentiful and chameleon females usually lay larger clutches, and the soil is still relatively fresh and easier to dig. Tropical species of chameleons, such as the Veiled chameleon (Chamaeleo calyptratus), the Senegal's chameleon (Chamaeleo senegalensis), the Carpet chameleon (Chamaeleo lateralis) or the Rhino chameleon (Chamaeleo rhinoceratus) will certainly choose to lay their eggs at the roots of a tree. As the weather cools for a few months and the humidity in the soil rarefies progressively with the following of the hotter months, the deep roots from such trees as eucalyptus and acacia in the deforested areas or the small city shrubs will keep on pumping the water from the ground. The eggs, being in close contact with the roots will seldom lack the proper humidity necessary to their development, and the bonus is upon hatching, soon after the first rains of the next season have started again, babies find an immediate refuge in the trees and food at plenty.

When I go for incubating chameleon eggs of "tropical species" I like the eggs to be able to touch each other, so I keep them in clutches. As I have noticed that eggs kept in clutches tend to hatch harmoniously, usually over a couple of days, whereas when eggs are kept singly, they may well hatch over a period of two months, I came to thinking that the eggs are able to hormonally communicate with one another, and that every egg is put to contribution to help a fellow in the need of oxygen or water whereas having several babies digging together to get out increased the chances of getting out of the ground.

For an incubating substrate of "tropical" species, I like to use a soil mix made of grinded and crushed vermiculite plus tiny hydroponics clay balls. This method avoids potentially harmful germs AND insects that would to be found in the natural soil and can ruin an entire clutch of eggs. The reason why I use vermiculite is because it is a natural occurrence (mica) of tropical, granites soils, and it helps to keep the substrate aerated instead having to deal with the stickiness the clay might bring if used alone. In the receptacle I fix a hollow PVC pipe on one side of the bucket, terminated with a syringe coming right out of the pipe so that I may use it to moisten the substrate at will. I do not leave the system open as it could let some bugs in, so I use a very fine mesh I place onto the cut I have made on the lid as anything else that would prevent proper water evaporation has often proven to ruin the incubation.

Loosened rope is put into place and is used as artificial "roots" for the eggs to come into contact with. The threads reach the very bottom of the receptacle. Disperse them so that they stay in close contact with the clutch before ending up tangled together and will act as natural drains to bring water to the eggs. Try to imagine the rope as being the tree with its root. For one part (the one that touches the bottom of the bucket), the threads have been untangled and set loose apart from one another, so as to make them look like roots. The other part of the rope is left untouched. Allow the eggs to be in close contact with these artificial roots.


The trick is to start to incubate the eggs in a moderately humid environment, to let the humidity slowly fall over a few months, during which it is necessary to keep the eggs at a cooler environment before raising the humidity along with the temperature to speed up and trigger the hatching process in the last month of incubation.


Temperature wise, embryos develop better if they are started at cooler temperatures to end up a bit higher. For those familiar with electronics and computers, I use an thermo electronic heat sink and a power supply that has the ability to switch the polarity of the current to incubate my eggs. Day time temps should start in their low 70's F (22 C) to gradually lower them to 65 F (18.5) in a matter of 2~3 months at the coldest, then slowly raise temps again, without raising the humidity of the substrate (but allow for the eggs to absorb humidity through the rope system) for another 3 months up to 75 F (24.5 C), even 78 F (26 C) for spp. like C. calyptratus, then start raising the humidity in the substrate (slowly and carefully) for the last 2~3 months whilst leaving the temperature at its maximum.

Incubating the eggs of altitude tropical species

Eggs of "altitude tropical species" are probably the most difficult to hatch for hobbyist due to the fact that they experience significant temperature and humidity fluctuations. Because they go through a long incubation period, hatching the eggs of these species in a proper manner without the use of a specific incubator is a real challenge in countries experiencing significant annual weather changes.

Although some people might experience successful hatching leaving their eggs in a shoe box locked inside a dark cabinet or closet, I believe the cool incubator is much well addressed to that particular type of chameleon eggs. As in for tropical species of chameleons, these eggs are usually laid at the end of the rainy season. They are going to be left inside the ground for several months at temperatures dropping from 71 degrees F (22 degrees C) to 61 F (16 degrees C) for most of them, whereas other are going to experience temperature as low as 40 F (4 degrees C) (C. campani, C. oshaughnessyi) at some extremes. Most of us are familiar with the 18 months Parson's eggs usually take to hatch, but in some cases, the eggs of some species of the parsonii group take almost 2 years to hatch.

It is important to remember to lower humidity and temperature in concert, starting to incubate these eggs at low temperature and high humidity will cause them to swell prematurely, to break or to die. It seems to be the cocktail of cool + dry for a few weeks followed by hot + dry for another few weeks then the hot + humid period triggers the embryogenesis inside the eggs.

Things you should know

Chameleon egg yolk are very rich in calcium and vitamin A. Just like birds are seasonal breeders and egg layers, it is possible that fertility is induced by the overall quality of food chameleons get to eat as captives. I ensure optimum quality food for my pregnant females, with enriched meals with nutritional supplements I concoct myself.

Some people using vermiculite have reported experiencing fungus growth on their eggs. If you bear in mind that the egg shell is coated with a bactericidal substance when expelled from the oviduct that is supposed to protect the egg, this is not a normal event. For this reason, eggs should be manipulated as little as possible and should not be washed. A well known trick is to tackle the problem is to sprinkle some athlete's foot powder on the eggs to get the situation back into control. I have seen some breeders who kept their Panther chameleon eggs in clear boxes under indirect sunlight. These eggs were coated with a fine layer of moss, giving the impression that the egg had turned bad, but to my surprise, the eggs hatched in a satisfactory manner.

The chameleon egg structure itself is going to go through some physical transformation as time goes by. Some eggs get red spots as they develop (C. pardalis), some eggs will flake (C. roperi, C. dilepis), some eggs thicken as they swell (C. globifer) and start to show some "Star pattern" as they mature. These star patterns are like deep lining reaching from one end of the egg to the other end. They help in the hatching process by creating some dents that go burst when the water pressure inside the egg and the babies movement signal the hatching time. All these are natural developments and should not be cause for worries. However, eggs that swell in an uneven manner, eggs with bumps, holes, no longer supple to the touch, eggs that have turned brown or that have shrunk by half their size are already dead and should be removed.

It takes patience to know whether an egg is fertile or not. Some eggs might have some very normal development only to fail at the very last stages of the incubation when you find out that cheesy material inside instead of the expected embryo. An egg should remain firm and supple to the touch, with a "bouncing" quality that can be felt at touch. Well advanced eggs can be candled, for this, an endoscope adapted to a light source, a bright white LED, a Maglitetm with an optic fiber appendix used for car mechanics or by gems collectors will do.

I do not know if the hatching process in the eggs of the "altitude tropical species" can be sped up or not as I have yet to experience with that, but I believe it can. The trick might be in shortening the diapauses through which the eggs go. Generally, I would rather keep the eggs on a slightly cooler and dryer side (at least during the first two thirds of the incubation term) as higher temperatures and too high humidity as a sure way to kill the babies inside their eggs.

In some extreme cases, eggs can dehydrate or can be drowned. Attention should be the key word for keeping the eggs hydrated enough without drowning them. If taken in the early stages, the eggs can be hydrated by being placed on a plate with shallow water.


There is much to be learned regarding the incubation of chameleon eggs. The subtle clues that the eggs take from nature to develop will provide chameleon breeders with a lifetime of challenge to discover and mimic.

Francois Le Berre

Francois Le Berre is the author of The New Chameleon Handbook and has written articles for Reptiles magazine. He is currently working on a revision of The New Chameleon Handbook.


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