Some lizards bask on sun-drenched rocks with surface temperatures in excess of 140 degrees to drive their heat-dependent metabolisms. This can be challenging to duplicate safely in captivity, but through a combination of proper heating devices, increased thermal mass and insulation, you can provide your lizard with a proper thermal environment. It is important to monitor the temperatures closely and provide your pet with a thermal gradient so that he can access a range of temperatures.
Radiant heat panels, heat lamps, heat tape and heat pads are all viable methods for heating your lizard’s cage. You must heat animals that bask frequently from above to simulate the sun, but you can use heat pads or tape for nocturnal or forest dwelling species. You can use heat lamps without a thermostat, but the other heating devices must be used in conjunction with one. Faux rocks and branches with internal heating components are unnecessary and of limited help in raising cage temperatures.
Regardless of which type of heaters you choose to use, you must always establish a thermal gradient in the cage, such that one side of the cage is warmer than the other. This will allow your lizard to adjust his temperature -- called thermoregulation -- as he sees fit. The amount of gradient necessary varies with the species of lizard, but in general, the cage should have at least 10 to 20 degrees difference in temperature between the coolest and hottest points -- some species may require gradients of several times that.
Reducing Heat Loss
Managing cage temperatures requires paying attention to the amount of heat added to the cage, as well as monitoring the amount of heat that escapes from the cage. Reducing the amount of heat escaping is a cost-effective, and often overlooked solution for achieving suitable cage temperatures. Insulating the cage is easy -- wood, foam or plastic panels attached to the sides of the cage will help to keep heat from escaping. If you struggle keeping your lizard’s cage warm enough, consider the type of cage you are using -- glass cages are very poor at retaining heat, and some plastic cages are nearly as bad. Thick wooden cages are heavy, but they retain heat much better than cages built from lightweight materials.
If you include large, dense objects in your cage, they will tend to heat up and slowly reradiate that heat back into the cage. These items help raise the temperature while the heating devices are on and after they have switched off. Essentially, anything that increases the mass of the cage will work, but dense items are best. Bricks and rocks are ideal, but branches or thick layers of substrate help a little bit.
It is important to check the temperatures in your lizard’s habitat frequently with a quality thermometer. Understand that surface temperatures -- typically measured with an infrared, non-contact thermometer -- and ambient temperatures -- measured with a standard thermometer -- are two different things. While some species from very warm habitats, like the spiny-tailed monitor lizard, bask on rocks with a surface temperature of 140 degrees, most lizards would die if kept in a cage with such high ambient temperatures.
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