Heating is one of the critical issues in keeping most reptiles healthy, and is especially
important with forest species that enjoy fairly steady warm, but not overly hot temps.
Dynamics of heat
Heat moves in a combination of three basic ways:
moves heat through direct contact. Touching a hot surface conducts heat to your finger. Heat is conducted to a tortoise through warm soil, etc.
occurs when the target is warmed by heated air or liquid. You boil eggs and heat most of your house with convection by heating the water or air. Convection heats a tortoise up by warming its air.
happens when the rays of a heat source (sun or a microwave, etc.) excite the atoms in the target and create heat. Sunburns happen because of radiation from the sun. A basking tortoise is taking advantage of radiation. (Please note that the term ‘radiating’ is also used to mean ‘sending in all directions’, so you can be said to be ‘radiating heat’ because you are heating everything around you – but you are usually doing it more by convection than radiation.)
The ‘Laws of Thermodynamics’ control how energy, like heat, moves. It always goes from the areas of greatest to least concentration, or from hot areas to cold areas. If you put a heated rock and/or a block of ice in a tub of water, the temperatures will soon even out. Water turtle keepers have an advantage here because water conducts heat better than air, and it holds it longer. This means that they can heat most of the tank with one good heater, and once it is at the right temp, it will stay there longer- using less energy. In a tortoise habitat, the heat tends to try to escape in all directions. If we heat the air, it just tried to rise out of the habitat. Covering the habitat slows this down, but causes other problems. Not only that, but if the habitat is in a cool room, as the heat escapes, it sucks the cold into it. You can reduce this heat loss by blocking air movement- insulating surfaces.
Heating for reptiles
When we talk about heating for reptiles, we generally look at five elements:
- Ambient Temperatures. This is the ‘room temperature’ of the habitat- what most of the habitat is set to. For most forest species, this should be around 80oF/27oc. One benefit of a large habitat is that there can be cooler and warmer areas scattered around it. The ambient temperature is generally the temperature of the room the habitat is in, although it can be provided by other heating systems.
- Warm Areas. Reptiles digest, bask, and recover from illness best in warmer than usual temperatures. Even forest species which are used to fairly steady temps benefit from an area in the habitat set to a warmer temperature, about 88oF/31oc for most forest tortoises. This is most commonly provided by a somewhat focused overhead heating source.
- Substrate Warming. The high humidity requirements of most forest tortoises can lead to substrates that are damp and clammy, even cold, especially in a larger habitat. (The heating system will probably warm a smaller habitat’s substrate adequately.) It is important to ensure that the substrate heating is gentle heat- no more than about 85oF/29oc, will not hurt a tortoise that touches it, and that it is safe for wet but flammable materials. Greenhouse or similar heating cables attached to the floor of the habitat work nicely. Use a good thermostat to control the heat safely.
- Nighttime Temperature Drops. Most reptiles benefit from lower temps at night. With forest tortoises, the reduced temps also mean naturally increased humidity, which helps keep them well-hydrated. Aim for about a 5oF/2oC overall drop. We can usually do this by just turning off the hot zone and lighting. Nicer reptile thermostats have options for a nighttime drop.
- Seasonal Temperature Changes. Most reptiles experience four seasons- spring, summer, fall, and hibernation. Forest species tend to have two seasons- wet and dry. On the Equator, there is almost no temperature difference between these two, but as we move away, the dry season gets to be about 10oF/5oC cooler than the wet season, with more daily variations. Forest tortoises do best if seasonal differences are followed. (By the way, summer for most of North America and Europe tend to be the ‘cool dry’ season for the tortoises.)
If this suggests that you need more than one heating system, you are right. The benefits of using a couple of independent systems include:
- Thermoregulation. This is the behavior of reptiles as they move between warmer and cooler spaces to control their internal temps. With several temperature levels, the tortoises should be able to find a nice spot no matter what they want.
- Redundancy. If one system fails, the other should keep things warm enough for
- Safety. With two separate systems, neither has to be too awfully hot, avoiding cooked reptiles.
- Control. It is usually easier to obtain exactly the temps you want with multiple systems.
- Humidification. Hot air is usually dry unless it is humidified in some way. A multi-stage approach usually allows better humidity regulation. See ‘Humidity’.
An ideal habitat
A very well-designed habitat would feature:
- Substrate that is always pleasantly warm, never ‘clammy’. This requires either substrate heating, infra-red heating, or warm air. It also often requires that the bottom of the habitat be insulated so cold does not creep in from underneath.
- A large basking area that allows the entire tortoise to warm up all over. Most single-source heating systems make small areas that make the tortoise too hot in a small part of the top of the shell, then do not warm up the limbs- especially if the substrate is cool. Think about trying to tan in the sun compared to trying to tan with a fancy flashlight. It make take a couple heating sources to accomplish this- like a small space heater and a few infrared heaters spread over the basking area.
- A cooler, shady, and humid area the tortoise can rest in, besides the hides.
Common heating techniques
|Forced Hot Air
|Warm Vapor Heat
Note- with any system using electricity, heat, plumbing, water, etc- be careful! Water, electricity, and living things do not mix. Please note that some heating pads and cables have fairly low absolute limits of heat produced- these would be considered much safer than pads or cables that can get very warm and may cause a fire.
If you were listening to your music, you have a few ways to control how loud it is. You can use bigger or smaller speakers, turn the volume up or down, move closer to or further from the source, add or remove materials blocking the sound, or add more speakers. We can do much the same with heat.
One of the best ways is to use a thermostatic control with a separate temperature probe. This is especially useful for things like ceramic heaters or under-tank pads. Other ways to adjust the temps include using multiple small heat sources; adjust the distance of the heater; add or remove insulation around the habitat; etc.
Be sure to monitor temps with a good thermometer or two. Usually, one is placed in the hot spot and another in a cooler area. I especially like digital thermometers that track high and low temps. The ability to set alarms if the temps get too hot or cold is a real bonus.
As mentioned before, heat (and humidity) is working hard to move from your nice warm tortoise habitat to the cooler room. One way to stop this is to trap heat we already have- or prevent cold from seeping in. Rigid foam insulation panels are great to insulate the bottom and sides of our habitats. If needed, we can even use them to make a box over our tortoise tables to trap heat and still allow plenty of fresh air.
Tortoises kept outdoors need protection from temperature extremes- a little misting in a corner for cooling on hot days, and a warmed shelter for cool days is a great idea. Your local farm supply or pet shop often has safe heaters for pets or farm animals that can be used in an outdoor shelter (assuming you can ensure that the wiring is safe). A good thermostat can kick them on when temps start to drop below about 60F. It is also helpful to insulate the shelter to hold daytime heat in.
- Use thermometers to
gauge the real temps in the habitat. Thermometers with alarms are
- Aim for a range of
with a warm zone of about 88oF/31oc.
Try to offer about 5oF/2oc
cooler temps at night, and think about offering a warm and a cooler
season for some species.
- Using separate
systems offers more safety and control.
- Safety first. Use
thermostats, circuit breaker outlets, GFCI outlets, etc. to keep