|Content of Keeping Monitors in Captivity
The furnishings in the enclosure provide the lizards with oppourtunities to hide, bask and
search for food. They appreciate a variety of different surfaces to climb on and because stone
and wood heat at different rates their use helps maintain the thermal gradients essential to
normal behaviour patterns. The furnishings greatly increase the surface area available to the
lizards for activity and should be chosen with care.
Stone absorbs heat slowly and retains it well. Judicious use of rocks in the enclosure is of
central importance in establishing the thermal gradients required. Avoid those with sharp
edges or that crumble when scrubbed - granite and hard sandstone are good choices. Tree
dwelling species which have only stone to climb on tend to wear their claws down faster than
they can grow and the number of rocks used in the enclosure depends on the habits of the
animals to be housed . In some cases a single large stone is sufficient, situated close to the
basking lamp, where it will continue to emit heat long after the lamp has turned off. For rock
dwelling species the enclosure should resemble a quarry. The bottom and sides of' the
terrarium can be partly covered with thin slabs of stone to which additional pieces can be
cemented to create numerous caves, ledges and overhangs for the lizards to explore. They
may also appreciate large elevated blocks of stone. Rocks used on the floor of the enclosure
should be heavy and have flat bases. Rock piles should be firmly cemented together, if rocks
are piled on top of each other the lizards will eventually dislodge them. A plastic hide box
covered with rocks provides a very simple cave.
Branches are essential for monitor lizards that like to climb. A walk through a wood will
usually yield many suitable pieces of tree stump and branch. Only take hard, dead wood that
has already become separated from its tree. Avoid decaying branches and those that might
ooze sap or resin. Make sure that all branches and stumps are secure and can not be shifted
by the lizards. Careful use of branches can greatly increase the available area of the
enclosure. Monitors from jungles and thick forests prefer to climb amongst a tangle of
branches but those from more open areas can do well with just a few large branches to rest
on. Small tree-dwelling monitors very much appreciate the shelter afforded by hollow
branches and will generally squeeze into the smallest shelter that will accommodate them. In
high enclosures beware of the fact that lizards may leap from the highest branch to the
ground and reduce the risk of injury by providing a soft substrate below. Smaller species
greatly appreciate the use of cork tiles on the sides of the enclosure, which gives them even
more climbing surfaces. For larger climbing species the walls should be covered with planks
of wood to which bark is still attached.
Monitor lizards need to be provided with plenty of dark retreats to help them feel secure.
Many keepers are inclined to be stingy with hiding places because they rarely see their lizards
otherwise. This is a mistake. Given adequate space most monitors eventually loose most of
their nervousness after prolonged periods in captivity, but if they are not able to conceal
themselves when they feel threatened they will never acclimatise properly. Many keepers
have found that elevating the enclosure a metre or so above the ground has a dramatic effect
in reducing the timidity of the lizards.
In the wild monitor lizards shelter in burrows, termite mounds, rock crevices, tree hollows, in
dense vegetation or under stones. These shelters are used not only to escape from predators
but to reduce water loss and maintain suitable body temperatures when conditions are
inclement. Similar shelters must be provided in captivity. Monitor lizards are very strong, and
if they can dismantle the furnishings in the enclosure they will do so. All rocks and wood
must be fastened securely to prevent risk of injury by minor landslides and tree falls. Providing
adequate hiding places is particularly important when several animals are kept together. The
smaller ones will greatly appreciate retreats that the larger ones are unable to enter. Many
species like to wedge themselves into very tight spaces, and careful planning is required if
you require immediate access to the lizards without recourse to a saw or crowbar..
Artificial burrows can easily be constructed by building a false floor into the terrarium with a
hole cut out of one corner to which a piece of pipe is attached. The pipe can be sealed at one
end, or left open to give the lizard a large subterranean chamber. which should also be
covered with substrate. Alternatively artificial burrows can simply be buried in the substrate.
Monitors prefer to dig or steal a burrow situated close to tree roots or rocks, so suitable
furnishings should be arranged around the edge.
Hollow branches are utilised by many monitor lizards who feel secure only above the ground.
Finding natural branches of a suitable size and shape may not be very easy, but nestboxes
similar to those sold for birds provide a good alternative. A number of shelters of different
sizes should be offered and some should be positioned as high as the enclosure will allow.
Rock crevices and caves are the usual hiding places of many species. If heavy stones are used
great care must be taken to ensure that there is no danger of collapse. Alternatively artificial
retreats can be made by carving out blocks of polystyrene (styrofoam) to a suitable shape and
coating them in a mixture of sand and epoxy resin. Furnishings made in this way can be made
to resemble simple caves or be as complex as termite mounds.
Monitor lizards appear to select basking areas with great care. Some prefer to bask on wood
or stone, others select exposed areas of ground. In all cases basking sites are somewhat
elevated. In the terrarium a variety of furnishings should initially be provided around the heat
source to determine the lizards' preferences (see below). Stone can get very hot when
exposed to heat but some lizards like to bask on surfaces that are uncomfortably hot to the
touch. Wood and organic substrates do not reach such high temperatures and may be
preferred by other animals. Each animal housed must have access to suitable basking areas
and great care must be taken to ensure that the lizards cannot burn themselves on a heat
source. Imagine the animal trying to burn itself by jumping at the heater, or standing on its
hind legs and trying to touch it with its tongue, and position the equipment accordingly.
Attribution / Courtesy: Daniel Bennett. 1995. A Little Book of Monitor Lizards. Viper Press U.K.