Husbandry of Monitors in the Subgenus Odatria
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.
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
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
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
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
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
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
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.