Captive Husbandry of Monitors in the Subgenus Odatria

Husbandry techniques vary widely between enthusiasts and numerous are successful. Many of the practices keepers utilize work because of their unique situation (geographic location, barometric pressure, external temperature, external humidity, etc.). To ensure the health and reproductive viability of our monitors, several guidelines and practices are followed and implemented here at Canadian Coldblood.

Captive Environment
Monitor lizards of the subgenus Odatria are extremely hardy captives and can flourish in a relatively simple enclosure. As a general rule, it is better to have an enclosure that is too large, than one that is too small. Many different types of enclosures have been utilized in our breeding efforts and all have been successful. It is not the type of enclosure (stock tank, aquarium, etc.) which is used that produces successful breeding results, but the internal conditions presented within that enclosure.

Depending on a hobbyist’s situation, a custom enclosure is usually preferred. An enclosure can be constructed that accommodates both the keeper and their monitors. In our experience, enclosures constructed out of _”plywood work best (Volume = 48” X 24” X 20”). Plywood acts as a good insulator and ads texture to the walls of the enclosure. The interior surface of the plywood enclosure is coated with a waterproof epoxy resin. Sliding glass doors are placed at the front of the enclosure rather than having a top opening design. This allows for stacking and easy access to elevated enclosures. An incandescent spot light fixture is mounted to the ceiling of the enclosure (at a distance of approximately _ the ceilings total length) and a fluorescent light fixture spans the rest of its length. These provide the basking area and ambient light required. Vents are installed along the walls of the enclosure and their number will vary depending on the style of vent being used.

A fine, granite based sand is used as substrate within the enclosure. For successful egg deposition the substrate should layered at a depth of 15cm (6”) or more. Flagstone is stacked securely below the basking spot. The distance between the spot light and the basking surface is approximately 15cm. This ensures that basking area will reach the desired temperature of approximately 50°C (120°F - 130°F). Basking and ambient temperatures within the enclosure may fluctuate due to external conditions. Flagstone is used for the basking area instead of a wooden stack for several reasons. Stone is easy to clean and holds heat well. This is beneficial because it provides a warm place to hide at night when the lights are turned off. Cage furniture consists of large pieces of bark stacked vertically along the back wall of the enclosure. This provides an elevated hiding area and better utilization of enclosure space. Smaller pieces of bark and branches are placed strategically on the floor of the enclosure. Other cage furnishing can be used as well without benefit or detriment to the enclosure inhabitant.

There are some critical environmental factors listed below that a keeper must provide and maintain in their enclosure if they plan on successfully breeding their varanids.

1. Substrate must be kept moist enough to hold a burrow, but not saturated.
2. Enclosures must contain a suitable number of inhabitants. Overcrowding will rarely lead to successful reproduction.
3. 24 hours of daylight is not necessary and monitors will breed with equal success when exposed to an average photoperiod.
4. UV radiation in the form of fluorescent lighting may be beneficial (more research is required), but it of no detriment.

Water, Food and Nutrition
Monitors in general are tenacious feeders when healthy. A good feeding regimen should leave your monitor hungry most of the time, but not underweight. Hatchlings and breeding females will require relatively more food on average for successful growth and reproduction. When planning a feeding schedule it is always good to remember that fat monitors are not necessarily healthy, and in general are less likely to breed.

Adult animals should be fed once every two days. Their diet consists primarily of insect matter (crickets and cockroaches), but may be supplemented occasionally with fuzzy mice. Monitors show a particular affinity for large prey items and will sometimes refuse food items that are too small. It is also worth mentioning the importance of gutloading your feeders. Insect prey items should be fed a variety of fruits, vegetables and grains on a regular basis. When these insects are consumed, their stomach contents (gutload) are passed onto the monitor. When feeders are fed a variety of nutritious foods, the need for a multivitamin is greatly diminished. Healthy feeder insects improve the overall health and reproductive success of all lizards. Monitors which are housed indoors and have no exposure to natural sunlight should be offered a calcium and vitamin D3 supplement on a regular basis. Vitamin D3 allows reptiles and other animals to metabolize calcium. UV radiation from the sun is a reptile’s primary source of vitamin D3. In the absence of natural sunlight, vitamin D3 must be supplemented.

Water is offered via a shallow dish. The dish should allow insects to climb out easily. Monitor enclosures are sprayed lightly every 2-3 days. The top layer of substrate and cage furniture should appear dry within 12 - 24 hours after spraying. The frequency of misting will vary based on your local relative humidity. In regions of low relative humidity, keepers might be required to mist the enclosure more often. As a general rule, your enclosure should not appear wet. Excess water can lead to secondary health concerns. In enclosures which contain reproductive females, it may be necessary to check the moisture level throughout the substrate. The substrate should be moist enough to hold a burrow, but not overly saturated with water.

Preparing a Monitor Colony
Ideally a hobbyist’s best option is to raise a group of hatchlings to adulthood. But in many cases this is not possible or necessary. Many successful breeding colonies have been assembled using adult animals when the following guidelines have been followed.

When deciding which animals to try and breed, it is important to choose animals that are not overweight or too thin. Generally, adult monitors of the subgenus odatria can be introduced to one another without incident (V. storri may be more difficult to pair or group as adults). If aggression is observed it is usually between two males in the presence of a female, or on occasion, an extremely territorial female towards another female. Very rarely is aggression observed between males and females (V. storri are an exception to this rule and very individualistic). Colonies should never have more than one male present for long periods of time. In cases where aggression is observed, monitors can be taken out of their normal or “home” enclosures and placed in a new enclosure with the other individuals of your desired group. This will eliminate much of the territorial aggression the individuals previously displayed. This method works very well when establishing pairs of V. storri. Once the monitors have been moved to their new enclosure territories will be established in a less violent manner. On occasion, cohabitants of a colony never do well together. Animals which tend to hide for the majority of the day and do not appear during regular feedings are usually under a lot of social stress and should be removed from the colony. Newly assembled colonies should be observed for at least an hour after introduction in order for the keeper to intervene if necessary.

Breeding
Successful propagation of any monitor species in captivity is no easy task. One of the major factors contributing to the limited popularity of varanids in herpetoculture is their reluctance to breed with regularity and predictability in captivity. Monitor lizards would easily rival the popularity of the leopard gecko or the bearded dragon if hobbyists were able to achieve the same level of reproductive success commonly obtained with these species. As few enthusiasts have experienced, monitors have immense reproductive potential. The key is finding the proper conditions to unlock that potential.

Once a proper environment has been constructed, nutritional requirements are met and a proper group or pair has been established (outlined in previous sections) the stage is set for successful reproduction. Monitor lizards will breed at any time of the year. But, there are external, geographic factors that stimulate monitors at our facility to go into a more definite reproductive pattern where the highest concentration of successful breeding and egg laying is observed. This occurs between the beginning of December and the end of June. This breeding season may vary depending on a hobbyist’s geographic location. Throughout the course of the year, photoperiod, temperature and humidity remain relatively constant within each enclosure.

Breeding monitors requires patience. Female monitors, like any other reptile, have a reproductive cycle which sometimes takes time to initiate. Males on the other hand are ready to copulate year round. More often than not, if the animals are compatible and their keeper is patient and unintrusive, breeding will eventually occur. In appropriate groupings, males will only pursue females with the intention of breeding when females are receptive. If a male is continually chasing females around the enclosure and is unrelenting in his breeding attempts, the animals should be separated. In this case it is probable that your group consists of more than one male, and if not, the females will likely never successfully breed with that male due to elevated stress levels. With due diligence on the part of the keeper and a little luck, successful copulation will be achieved.