A brief history of reptile keeping views

Reptile and Amphibian keeping has a long history in the western world.  Interestingly,  pioneers intended to keep animals in naturalistic, planted vivaria.  Despite the beautiful appearance of showcase vivaria, larger sized collections and a different view of hygiene in the 1960’s to the 1990’s of the last century promoted a new way of reptile keeping.  This was largely a reductionist approach; with cages that could be easily cleaned using newspaper or wood chips as substrate.  While we don’t oppose either way of keeping your reptiles, we want to provide an overview of the general requirements that need to be met to keep animals in terraria healthy and eventually breed them.

Either way, meeting the husbandry requirements of a reptile should be done on a species-specific basis.
Field data on diets and microclimate provide an indication on husbandry requirements. Providing ultraviolet light via suitable lamps seems beneficial for most species.
Providing a varied diet seems beneficial for most species.
Providing several microclimates per enclosure seems beneficial for most species.

Space

The dimensions of the terrarium are the first criterion to focus on. Much like humans, animals need to be active to be healthy. A too small terrarium will prevent normal activity patterns and will lead to obesity as well as weak muscle tone.  It is also important to chose a large enough enclosure to be able to provide different temperature zones for the animal to chose from and search its optimal micro environment.  Remember, neither constant warm temperatures nor constantly cold temperatures are beneficial for West Indian boas!

Climbing opportunities

All West Indian boas fall into the arboreal/semi-arboreal and mostly terrestrial habitat types.  Most will climb at times, some more, some less.  We believe that perches – either natural branches or artificial branches – provide a good opportunity for the snakes to exercise and belong in every terrarium.  Branches allow for thermoregulation of body temperature, aid in reproduction, feeding response, etc.  There are many upsides to providing branches, even for the more terrestrial species.

Substrate

The variety of grounds to keep your boa on is almost limitless: garden dirt, Coco humus, Aspen bedding, Louisiana Moss, Peat moss and Cypress mulch to name a few.  They are commonly available and relatively inexpensive when purchased in bulk.  The concept of a “living soil” in the terraium functions well with West Indian boas.  See Naturalistic Terraria below for more information.  Whatever your choice, the standard that feces need to be removed asap and that the soil is neither too dry nor wet needs to be emphasized.

Water

Despite the fact that some species occur in very arid environments (e.g. Chilabothrus fordii, C. granti), we consider it important to provide fresh water ad libitum at all times. The water tub should be large enough for the boas to take a soak if they want to, but must also be easy to clean.  Water should be replaced immediately upon soiling or at least every 2-3 days, whether soiled or not.  Observe your snakes and make sure they recognize the water for what it is.  Rarely, a second water container may be warranted; add one if a boa appears dehydrated, has a poor shed or the bowel movement has a dry or “hard” appearance.  Materials can be glass, ceramics/china, stainless steel or high grade (food secure) plastics.  Elevated water bowls are beneficial to those boas that are arboreal or semi-arboreal.  It also makes cleaning the vivarium easier for the keeper, though the first and only concern is for the boa and its welfare.

Humidity

The habitats of West Indian Boas range from moist to dry. Humidity levels that are necessary for proper sloughing and general physiological processes can be established by a variety of methods. Water tubs made out of fired clay can be used since the porous structure gives of water to the environment. Living plants in the cages contribute to a good humidity level by photosynthesis. Daily misting of cages is not necessary except for  breeding season, where the misting helps to stimulate breeding. Excessive humidity can cause respiratory illness, blisters and ulcerations.  A humidity monitor is recommended for all cages if ambient humidity levels are not the norm in the vivarium.

Air Circulation

Stagnant air is the cause of almost every respiratory illness.  Ensure there is a fresh exchange of air allowed by your choice of vivarium.  How you accomplish this will depend on the nature and build of your enclosure.  It may need to be modified or altered to accomplish this.  Fans in the facility can provide some relief as long as they do not force air directly onto or into an enclosure.  The importance of this cannot be overstated.

Materials to build your terrarium

Terraria can be build from different materials and in different styles. Each materials has pros and cons and we briefly list them below. Note that thermal insulation is a double edged sword for keeping reptiles. Some materials insulate better than others. While good insulation has the beneficial effect to keep the heat inside your terrarium and thus will prevent your vivarium from cooling off too fast, it can also be problematic when overheating is an issue and in addition when the night-day cycle can’t be achieved because too much heat is kept in the enclosure during the night. Keeping your reptiles at too warm temperatures without the possibility to thermoregulate and seek out cooler places  will ultimately result in health problems.

• Glass
  • Pros: easy  to clean, humidity and water resistant, several ready made enclosures with good design exist (e.g. Exoterra) these can be minimally modified to house (young) boas properly. Environmentally friendly.
  • Cons: heavy, difficult to machine, several hands needed to transport medium sized to large terraria, very large enclosures can’t be easily transported without disassembly, fragile.
  • Thermal insulation properties: glass is usually not a good insulator.
• PVC or other plastics
  • Pros: Lightweight, humidity and water resistant, easy to machine.
  • Cons: environmentally disastrous.
  • Thermal insulation properties: Depending on the material (foamed PVC or thin Plastic) can be highly insulating or giving away heat easily.
• Premade plastic containers reftrofitted as terraria
  • Pros: Cheap, water resistant, ready made, easy to machine, some need only minimal alterations, can serve their purpose in larger collections or as baby snake enclosures.
  • Cons: No eye candy. Snakes can’t be observed without disturbing them unless glassdoors are fitted in. Prevents the keeper from really enjoying their animals. Often air circulation is not sufficient resulting in health problems. Lights are difficult to fit in. Dimensions are too small to keep larger boas permanently, usually not environmentally friendly. Finally, the snakes are stimulated by the  outside world. Often the keeper is observed as much by the animal as vice versa. This is made impossible when using plastic containers.
  • Thermal insulation properties: Due to thin material, usually not a good insulator.
• Wood
  • Pros: Easy to machine with household tools. If well planned easy to assemble and disassemble.
  • Cons: Heavy, large sized terraria made of wood can’t be transported in one piece, not really water or humidity resistant. Needs coating.
  • Thermal insulation properties: Wood is a good insulator.
• Aluminum or metal
  • Pros: can be lightweight, durable, water resistant. Medium easy to work with. Some experience and tools needed.
  • Cons: expensive.
  • Thermal insulation properties: metals aren’t good insulators.
• Screen or wiremesh cages
  • Pros: good ventilation, often lightweight; if you live in an appropriate climate, your boas can benefit a lot from a mesh cage. If placed in a garden, always ensure that the boas can avoid the sunlight and hot temperatures, since overheating kills reptiles easily.
  • Cons: humidity is not kept. Commercial cages are usually not stable enough to withstand medium sized to large boas.
  • Thermal insulation properties: screen cages are obviously not good insulators.
• Particle board with coating
  • Pros: Often cheap, easy to machine with household tools.
  • Cons: Heavy, big sized terraria made of this material can’t be transported in one piece, not water or humidity resistant, will look ugly after a couple of years.
  • Thermal insulation properties: depending on the thickness and material properties. Generally rather well insulating.
• Stone
  • Pros: If you own the place and don’t plan to move, why not build a terrarium like a zoo? Stable, several options are possible. Makes sense only for large sized terraria or large species.
  • Cons: Heavy, impossible to transport, every planning mistake costs lots of time, money and energy to rectify.
  • Thermal insulation properties: can be pretty good, depending on design.

Light, Heat and Temperature

All of these are interconnected and it is almost impossible to talk about heat or light or temperature alone. Light and heat radiation are parts of the electromagnetic spectrum (see figure below). It is important to consider that the human perception of visible light is not exactly the same across species. Thus, a light source that we consider as very bright might not emit the wavelength that is most stimulating for other species receptors and thus we might see things brighter or less bright than other species under artificial light.

Nothing shines like the sun!

This trivial yet telling sentence indicates that despite great advances in lighting technology we are not even close in mimic natural lighting. However, light and heat are especially important when dealing with poikilotherm organisms like reptiles.

Heat can be transferred by:

Conduction: 

Sources in the terrarium are a heat mat or a substrate heater or a heat rock: the transfer of heat by means of physical contact. The larger the contact area, the more efficient the heat transfer.

Convection

almost all heat sources create a form of convection: the movement of heat by moving air. Convection results from the differences in the densities of the air at different temperatures. As air raises in temperature, it becomes less dense and thus lighter thereby rising above its cooler and denser counterparts, which in turn sink.

Radiation

Incandescent light bulbs operating with a tungsten filament (the old style light bulbs and also halogen light bulbs, but also Mercury discharge lamps produce ): energy is transferred in the form of electromagnetic waves. As visible in the image above, the different forms of radiation comprise the electromagnetic spectrum and are characterized by their different wavelength. The highest energy (aside from gamma- and X- rays) is is transported by ultraviolet rays, followed (in order of decreasing energy and increasing wavelength) by visible light rays and infrared. While the the shortest wavelength forms of radiation are most penetrating, the optimal wavelength for reptiles and especially pregnant reptiles appears to be the Infrared A and Infrared B type.

Heat and pain receptors are located directly under the epidermis in the upper part of the dermis, they are less activated by IR-A than by IR-C (which intensifies energy in a smaller volume of skin). Therefore, reptiles might leave a heat source, because their epidermis is heated, whereas their core is still “cold” (think of deep fried ice cream!). For a pregnant snake, this means she can’t amass the number of heat hours she needs to develop her young.

Considering the initially good breeding success with live bearing snakes when thermal radiation (and lighting) technology consisted mainly of IR-A emitting incandescent light bulbs with the often frustrations seen today (Technology = heat panels, emitting IR-C)

A bit more technical: In general, thermal radiation occurs outside the visible spectrum, in the Infrared spectrum. The Infrared spectrum is divided in three parts, the short wavelength Infrared-A (IR-A = 780-1400 Nanometer (nm)), adjacent to the visible light. IR-A can penetrate the skin more than 5mm deep. IR-B (=1400 – 3000nm) penetrates the skin up to 2.5mm IR-C (≥ 3000nm) penetrates lass than 1mm in the skin. Thus IR-B and IR-C are being absorbed in the epidermis (the upper skin layer), whereas IR-A penetrates deeper and allows for warm up of the whole body .

Heating sources and methods

There are a variety of methods to provide heat to your vivarium.  The type of heat source will depend on your choice of vivarium type, its size and construction materials used.  Light sources can provide visible light as well as the necessary UV requirements and heat in form of Infrared light.

Heat panels, heat tape, radiant heat panels, ceramic heat bulbs (with wire cages to prevent boas from burning themselves) and heat pads can also be used.  They can be used in combination with light sources, given the type of enclosure used or desired temperature regimens.  They can also provide supplemental heat for gravid boas, etc.  The size of the boa may dictate the type and size of heat source used to achieve proper ambient and hot spot temperatures.

Note that several heat sources provide different qualities of heat. A body can have a high surface temperature but the form of energy transfer prevents the heat from warming the boa up. Sounds complicated?

Let’s go into the physical properties of heat transfer: Heat and Temperature are two different things. Temperature describes the state of a body (imagine a metal block). Imagine you put this metal block in a fire and after 10mins take it out. The temperature of the metal block has changed (and thus the energy it contains). The block is now in a room at ambient temperature and will give away the energy to the air and the other objects in the room.

Thermostatic controls of  heat sources

No heat source should be used without some method of control over the temperature output and duration of that output to influence the DTH’s (day time highs) and NTL’s (night time lows).  There must also be a method to control the duration of DTH’s and NTLs, for both routine health maintenance and breeding activity.  There are a variety of products on the market that range from a simple temperature dial to sophisticated devices that can be remotely adjusted and monitored.  Some of the devices are combined thermostats / hygrostats. The latter can monitor and activate water misters to maintain appropriate  humidity levels.

The simplest thermostats are those that keep only one temperature. These are relatively cheap to buy, however keep the cage at that temperature the whole time. Better suited for keeping reptiles are  thermostats that combine an internal clock and have several timeslots that can be programmed to different temperatures. This allows a night time drop of the ambient day time temperature.

Two functional principles are available.

• On-off thermostats switch a heat source on, and once the temperature is reached, switch the heat source off.  This method of heating is considered less efficient than the proportional method below.
• Proportional or dimming thermostats dim the voltage the nearer the temperature is  to the set temperature. It is important to keep in mind that not every heating element can be dimmed.

Food

Most West Indian Boas eat rodents as adults, the exception are Chilabothrus gracilis and Chilabothrus granti which are saurophagus during their whole life. Newborn West Indian boas of the Genera Corallus and Chilabothrus are almost exclusively saurophagus. This needs to be taken into consideration when planning to breed or starting with young snakes.  The most important issue is many of the Chilabothrus and Corallus young will NOT take anything other than ectothermic prey as first foods.  Some may require assist feeding of these prey items.  There are no substitutes or short cuts when working with these boas.  If the needed prey items cannot be provided it is best to not keep these delicate boas.  Starvation fatalities are an unacceptable loss in this day and age, given the rarity of most species ex situ.

Environmental enrichment

A well planned enclosure takes several aspects of the animal into account. Aside from the obvious parameters, such as dimensions of the enclosure, appropriate temperature, basking opportunities, humidity, perches etc. The well being of the animals is also dependent on stimulation from the environment. Huff coined the term “captive stagnancy” . Which describes the snakes adaptation to the captive environment to a degree where the animal becomes lethargic and overall inactive. He suggested to change feeding schedules and prey items and amount as well as changes in the terraria to stimulate activity.

The cognitive abilities of reptiles in general and snakes in particular have in the last two centuries been considered as limited or primitive. Recent research began to transform this view. It was discovered that reptiles are more than primitive insitinct based biological machines and instead show complex social behaviors, intellectual and learning skills and even engage in play . A behavior defined as “repeated, seemingly non-functional behavior differing from more adaptive versions structurally, contextually, or developmentally, and initiated when the animal is in a relaxed, unstimulating, or low stress setting”.

Until lately this behavior, which is a sign of intelligence, was thought to occur only in warm blooded “intelligent” animal species such as apes, dogs, sea otters etc. Convincing examples of play have been found in lizards, turtles, and crocodilians. Whether snakes play or not is hard to determine, given their close relationships with lizards, it appears possible that this trait might be present in the whole squamate lineage despite conclusive evidence at present.

Enrichment strategies are plentiful and can include also cohabitation with conspecifics or other species. General considerations to be taken into account are that any cohabitaion with other animals might not work as planned and thus making it necessary to separate the animals again. Keep enough extra enclosures at hand to face this possibility.

Further enrichment strategies can include also different chemosensory cues, presented at various times and intensities to the snakes . Any stimulus that keeps the reptile brain active is advantageous.

An active stimulus can also be achieved by target training. This method to train animals has only in the last decades been employed to work with reptiles. Mainly crocodilians and lizards. However, target training has recently been employed with snakes with interesting and somewhat promising results.

No matter which environmental enrichment strategy you chose, a stimulating environment is certainly beneficial for the health and well being of the animals and keepers alike.

Further recommended reading:

Citations