BREEDING
When maintained properly, green water dragons readily breed in captivity. Experts recommend that the animals are at least two years old and 2 feet in total length, have good weight, and appear healthy prior to breeding.
For two months during the late fall or winter, reduce the photoperiod to ten hours of daylight and fourteen hours of darkness. Lower the daytime temperature to 75–78° F, with the highest temperature under an incandescent spotlight at 80–84° F. Decrease the nighttime temperature to 68–74° F. Reduce the feeding schedule to once a week, and offer food in late morning or midday.
After the fall/winter rest period, resume the normal temperature, photoperiod, and feeding regimen. Within a few weeks males begin to exhibit breeding behavior, which consists of chasing females, head bobbing, and attempting to copulate. During breeding, the male seizes the female by the nuchal crest (above the neck) and lightly twists its body to insert a hemipenis. Copulation lasts from ten to twenty minutes. Remove females from the male’s enclosure for a week and reintroduce them into the male’s cage during the breeding season to increase the potential number of successful copulations.
Females lay eggs about two months after copulation. As gestation progresses and more of the abdominal cavity is filled by developing eggs, some females show a preference for small prey items instead of larger food, such as weaned mice. Depending on the female’s size, it will lay a clutch of four to fourteen eggs. There are reports of very large females laying even larger clutches. If a female is in good health and well fed, she may lay a second clutch of eggs three to four months after the first clutch.
A melanistic (left) and a normal colored (right) juvenile water dragon meet nose to nose on a branch.
A sailfin lizard (a related species) breaks out of its shell.
Egg Laying and Incubation
Place a layer of sandy peat moss 8 to 10 inches deep in the enclosure for gravid females to lay their eggs. If you place a board or a section of cork bark on top of the peat/sand area, many females will dig a nest starting at the edge of these structures and end up digging a burrow underneath. Once the eggs have been laid, carefully dig them out and move them to a suitable incubator.
Incubation
For incubation, put the eggs in an incubator in moistened vermiculite. Use equal amounts of vermiculite to water by weight or ten parts vermiculite to one part water by volume (10:1). Bury the eggs on their sides with one-third exposed above the vermiculite. The eggs should not be turned during the entire incubation period so mark the tops with an “X” using a magic marker if you need to move the eggs. Place a layer of moistened sphagnum moss on top, and maintain the eggs at 84–86° F. Well-known reptile veterinarian, Douglas Mader, D.V.M., recommends incubation temperatures of 88° F, but I suspect that this may be in the upper limits of suitable temperatures and that upward fluctuations could prove fatal in the latter stages of development. At exceedingly high temperatures, the water dragon’s metabolism may demand more oxygen than the amount able pass through the eggshell and membranes.
The striping on the backs of most juvenile water dragons generally fades as the lizards grow into adults.
Lightly mist the surface of the eggs every one to two days. This procedure, also recommended by Mader, has resulted in numerous successful clutches.
Building an Incubator
To construct an incubator, purchase at least a standard 20-gallon aquarium, and add 3 to 3½ inches of water and a 75-watt submersible aquarium heater. Add bricks or a welded wire frame to allow you to place a plastic storage box filled with the appropriate incubation medium in the aquarium. Put a thermometer inside the storage box, and adjust the temperature using the thermostat on the heater. Set a custom-made lid of polystyrene on top of the aquarium and allow at least an hour before and between thermostat adjustments. Electronic digital thermometers sold in electronic supply stores are extremely useful tools for incubators. You can place the sensor inside the container and the digital display thermometer, kept on the outside, will give a continuous reading of your incubation temperature. Hatching will occur under the above conditions after about sixty-five days. The lizards will hatch over a period of twenty-four to forty-eight hours.
Hatching Failure
The most common complaint of prospective water dragon breeders is hatching failure of full-term embryos. Excessively high incubation temperatures may cause this problem, but there are other possible causes that deserve investigation. If the moisture level of the incubating medium is too wet or too dry, it will affect the internal pressure of the egg, as well as the condition and turgidity of the eggshell, and therefore may make it more difficult for a hatching lizard to rupture the shell.
Finally, there is the strong possibility that the health and diet of the mother has a significant effect on the nutrition available to the embryo and on the structure of the eggshell. Feeding adult animals a varied, high-quality diet appears to be important. Carefully monitor your animals and keep detailed records on husbandry and incubation methods; these techniques provide invaluable information that will help you to make the adjustments necessary for success. Whatever you do, don’t give up. We all need to work on establishing captive breeding populations of these wonderful lizards.
Green Water Dragon Morphs
Adult water dragons are a uniform green color with little pattern. From a herpetocultural standpoint, this lack of variation limits the range of potential morphs that can be obtained through selective breeding. With green animals, a common variant involves a reduction of yellow pigment (genetic, dietary, or environmental), which results in animals with varying degrees of blue. Examples of this can be found in both green amphibians (green tree frogs and bullfrogs) and green reptiles (green tree pythons, green iguanas, and basilisks). Interestingly, one enterprising herpetoculturist is breeding a hypoxanthic (reduced yellow pigment) line of green water dragons that are an attractive aqua blue and marketed as “sapphire dragons.” Another morph results in adults that retain the lateral, light-colored bars of juveniles (marketed as “tiger” water dragons). In time, with greater efforts to captive breed this species, other interesting morphs may become available.
