Tree Skinks Are A Social Reptile

As an owner of an exotic pet such as a reptile, you have an obligation to provide your pet with a good captive environment, good nutrition, and enough attention that you are in tune with its needs.  When a captive reptile is forced to live in a situation that is inappropriate in fundamental ways, it become stressed.  If the situation doesn’t improve, this stress becomes a chronic debilitating condition that suppresses the immune system, alters the endocrine system, and increases the need for certain nutrients.  A reptile that is in a state of chronic stress is more likely to develop abnormal behaviors, contract infectious diseases, and have trouble maintaining a normal weight, either becoming thin or obese.  This article covers key concepts that will help you provide the care your reptile needs to sustain normal behaviors and health.

Preferred Operating Temperature Zone (POTZ) is the range of temperatures that best support a reptile’s physiology throughout its diurnal, season, and annual cycles.  The core body temperature of a reptile varies based on its physiological needs.  For example, a reptile that has just eaten a large meal often seeks out warmer temperatures than a reptile that has eaten recently because the enzymes that facilitate digestion work better at higher temperatures.  Most reptiles are cooler at night than during the day and that change in body temperature may facilitate some of the repair enzymes that are associated with sleep.  A gravid female will often bask for longer periods of time than a nongravid female, and there are many other examples where a reptile seeks out a different core body temperature depending on a variety of factors.  Since it is impossible to know what temperature is best for a reptile at any given time, the captive environment needs to provide a range of temperatures that allow the reptile to shuttle back and forth based on its innate physiological needs.  Typically this is achieved by having a basking spot at one end of the cage to provide a warm area while the other end of the cage is allowed to be cooler.  Unfortunately, the size of most cages tends to create fairly linear environment (hot end, cold end) which is somewhat different from the mosaic of temperatures a reptile would find in the wild.  A much larger cage, one that has patches of warm and cool spots, some of which are in moist areas, some in dry areas, some in brightly lit areas, and some in darker areas, more closely replicates the natural environment, will promote a wider range of naturalistic behaviors and may be key to succeeding with species that have not historically done well in captivity.

Preferred Operating Illumination Zone (POIZ) refers to the range of visible and near-visible electromagnetic radiation (i.e., light) a reptile is exposed to in the course of is lifetime.  Although we frequently only think of this in terms of light provided by the sun, night has a variable cycle of light provided by the moon.  Illumination is a combination of the color rendering index of light provided, as measured in thousands of degrees Kelvin (°K), the wavelength of light provided, as measured in nanometers (nm), and the intensity of light.  Intensity of light may be assessed in two ways. Radiant flux is the total power of light emitted at all frequencies and is measured in watts (w). Luminous flux is a weighted measure based on the optics of the human eye and what wavelengths are visible; it is measured in lumens. Reptiles perceive light in the ultraviolet wavelengths that are invisible to human eyes.  Thus a light source that appears white to the human eye may actually have a lot of ultraviolet in it that would alter the color perception of a reptile exposed to that light.  These subtle differences in illumination may have profound impacts on why certain species of reptiles do not thrive in captivity.

Illumination must take into account many factors to provide a light that allows the reptiles to see things that are important to it.  The colors of a mate or potential rival, the wax trails that reflect ultraviolet light and indicate a reptile has marked its territory, and the colors and movements of food items.  It must provide physiologically relevant light, such as ultraviolet-B to support the metabolism of vitamin D and calcium.  It may provide a source of heat. Typically, combinations of fluorescent and incandescent bulbs are needed in order to accommodate all these diverse needs.

Diurnal and annual cycles, important to establishing reproductive cycles, are established by the regularity of the photoperiod and the waxing and waning of day lengths as seasonally appropriate.  Timers are needed for the lights to turn on and off regularly and establish the photoperiod--depending on human memory to do so will insure that the photoperiod varies on a daily basis and may disrupt reproductive cycles. 

Preferred Operating Humidity Zone (POHZ) is the range of environmental and atmospheric moisture needed to promote optimal health.  This too varies depending on innate physiological needs.  For example, a reptile that is shedding typically needs a more humid environment in order to successfully shed the skin over certain parts of its body, such as its toes and tail tips.  Inappropriately low humidity often results in large sheets of shed skin remaining attached to its body.  If exposed to a constantly high humidity, a reptile may develop skin infections and even slough some of the skin on the pads of its feet.  There are some counterintuitive differences in humidity needs.  Many desert reptiles, such as gila monsters, have very permeable skin and quickly lose water when active above ground.  The majority of their time is spent in burrows underground with very high relative humidity so this permeable skin allows them to actively uptake moisture from this environment.  The cost is that they lose water rapidly above ground during the drier parts of the year.  Conversely, many tropical rainforest reptiles have very water-resistant skin which helps protect them from aqueous desquamatization.  Typically, the humidity will vary between day and night and between seasons.  It is essential to know the natural history and climate patterns that a reptile would experience in the wild to offer the POHZ.

Preferred Operating Auditory Zone (POAZ) is the range of vibrations including audible noises that a reptile would experience in the wild.  This is often overlooked as a source of stress in captive reptiles.  The common pet reptiles come from wild habitats that are quiet other than bird vocalizations or insect noises.  The bearded dragon living in a cage on top of stereo speakers is enduring vibrations that are completely outside the range of vibrations it would experience in the wild.  More subtle vibrations may contribute to problems, such as a television playing late into the night, an aquarium pump that vibrates against the cage, or the buzzing of a fluorescent light ballast.

Preferred Operating Dimensions (POD) takes into account the space that a reptile occupies throughout its activity period.  It is important to recognize that not all space is created equal for all species. For example, an enclosure that is perfect for a tree-dwelling day gecko is likely to be miserable for a ground-dwelling barking gecko.

For arboreal reptiles, the cage needs to be vertically-oriented with lots of climbable spaces that are vertical or angled.  Horizontal perches should be placed a various heights.  Hollow cork tubes, bamboo tubes, and PVC pipes may be used to create hiding spots throughout the upper reaches of the enclosure.  Perches and climbable space needs to bring the reptile into all the various environmental zones described below (e.g., basking spots, uvb-illumination, etc.).  Most arboreal reptiles will do poorly if they perceive they are too close to the ground.

Terrestrial reptiles need a horizontally-oriented cage with a modest amount of height, perhaps only as tall as 1.5 times the reptile’s total length although more height may be beneficial for some species.  The more horizontal space, the wider range of microhabitats you can create by manipulating the environmental zones.  Most terrestrial reptiles need a little bit of variety in the enclosure, such as rocks, logs, or low-lying branches, and plenty of opportunities to hide in cork hollows or other furniture placed on the ground.  Substrates that can be burrowed into are appreciated.  Depending on the reptile, cypress mulch, washed clean play sand, or a “forest mix” of varying amounts of peat moss, orchid bark, and sand work well.

Fossorial reptiles need a horizontally oriented cage with minimal height above the soil surface.  The substrate needs to be appropriate.  For many reptiles, a forest mix that retains moisture and can sustain the shape of a burrow is important.  For others, such as sand skinks, a looser sand mix is appropriate for them to “swim” around the enclosure.

Semi-aquatic reptiles such as the caiman lizard (Draceana sp.) and water monitor (Varanus salvator) typically need a bathing area that is sufficient for them to fully submerge and swim a few body lengths.  A bowl of water is usually not sufficient to keep these reptiles healthy.

Preferred Social Environment (PSE) refers to the interactions a reptile has with others of its own species as well as other animals (and humans) it encounters.  The social needs of reptiles are poorly understood.  Many live in complex hierarchies and have territories they defend against intruders.  Monogamy and parental behavior have been noted in some species.  Some, such as bearded dragons and monitor reptiles, appear to develop a true bond with their caregivers and even with cage mates of other species.

Common mistakes are to have too many reptiles in a cage, to maintain incompatible species in the same room (e.g., predator-prey), or to house incompatible age-classes together.  If a reptile can sense a threat and cannot get away, it may be stressed.

If you are unable to provide an environment that is right in every respect, you are creating a situation where your reptile is likely to end up with health problems.  Think about what is best for your pet and either correct the problems or donate your pet to someone who is better equipped to care for them

Copyright 2008
Kevin Wright and Jay Johnson
Arizona Exotic Animal Hospital, LLC
744 N Center Street
Mesa, AZ 85203
info@azeah.com