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4: THE IMPORTANCE OF HEATING AND LIGHTING

Providing proper heating and lighting is essential to keeping caged bearded dragons healthy. The dragons’ activity and metabolic processes depend on proper light and heat gradients. Without them, your dragons will not survive.

Heating

Providing adequate heat is critical to the welfare of bearded dragons, and there should be a 20-degree gradient between the top of the basking rock and the cool side floor. The primary source of heat should be a clear (not red) incandescent bulb or spotlight in a reflector-type fixture (clamp light) capable of handling the wattage and heat output. A fixture with a ceramic base and no electrical switch in the base typically lasts longer for this kind of use. Look for a fixture with a switch on the cord or plug the fixture into a surge-protector unit and use that switch to turn it on and off. Clamp the fixture to the short side of the tank over the basking site.

For juveniles, 95–100 degrees F is a good place to start for the basking-site temperature, with the cool side floor at 75–80 degrees F. You may find that your dragons like to bask at different temperatures, and you can achieve flexibility by trying different bulbs of different wattages, such as 60 watts and 75 watts, too see which bulb results in the desired temperatures. Another option is to plug the fixture into a light dimmer, which will allow you to adjust the heat output.

To determine the correct temperature for your bearded dragon, watch its basking behavior. If the dragon is happy at a certain temperature, he will be brightly colored and standing erect on, not next to, the basking rock. If he stands near the basking site, it is likely too hot. In this case, adjust the heat to 5 degrees lower and see how your bearded dragon reacts.

Watch your dragon’s basking behavior to provide its preferred temperature.

Some adults like it hotter. If your beardie spends all day on the basking rock, it may be too cool for him. Try raising the temperature at the basking site to 105 degrees F and see what happens. If his color is brighter, he looks more alert in his stance, and he tends to move over the enclosure at various times of the day, you have it right.

Placing a heat-absorbing landscape material under the basking light can help heat up a basking site more effectively. The problem is that the site can overheat, too. Artificial rocks made from molded resin work very well. Never use a “hot rock” because bearded dragons have sensitive stomachs that can be burned.

If you live in a very cold area, you might need supplemental heating at night. If the room where your bearded dragon’s enclosure is falls below 68 degrees F at night, there are red light bulbs or ceramic heating elements (that produce no light) that can supply the additional heat needed to bring the tank or enclosure temperature up to 68–70 degrees F, but no higher than that. Bearded dragons need a nighttime drop in temperature to cool down, but if the temperature inside the enclosure falls below 68 degrees F, your dragon runs the risk of contracting a respiratory infection.

Understanding Heat

A key to successfully keeping reptiles is understanding the role of heat. Bearded dragons are ectotherms, which means that they depend on environmental temperatures to achieve and maintain optimal body temperatures. However, bearded dragons are not passive in their relationship with environmental temperatures. They adjust their body temperatures with various behaviors, including selection of thermal zones. For example, after a cool night in the desert, a lizard may crawl out into sunlight at midmorning, flatten its body, and adopt an overall darker coloration to increase heat absorption so that it can quickly warm up to an effective operating temperature, which allows it to be alert and act quickly.

Once it reaches an optimal temperature, the lizard may hunt insects, perform displays for other lizards, and be watchful for potential predators. However, as the midday sun causes air and surface temperatures to rise even higher, the lizard may begin to overheat and will move out of the sun to rest in shade or under shelter until the temperature cools down. This is known as thermoregulation, and it is a critical aspect for those of us caring for our dragons in indoor enclosures. When we talk about thermoregulation, or assuring a proper temperature gradient in a bearded dragon’s enclosure, this is what we mean. As mentioned the bearded dragon needs to be able to move from the basking spot to a cooler zone that is 20 degrees cooler than the basking spot. In this way, it regulates its internal body temperature as necessary. Heating up under the basking light will stimulate hunger and allow for digestion of food and calcium supplements. Moving to the cool side of the enclosure allows him to cool down, lowering his internal body temperature.

One of the interesting features of reptiles is that that they heat up quickly and cool down relatively slowly. In fact, one of the studies showing this was done with the Eastern bearded dragon (Bartholomew and Tucker, 1963). Individuals with a 68-degree F body temperature placed in a 103-degree F chamber heated up to 101 degrees F in about thirty-eight minutes but, under reverse conditions, required more than fifty minutes to cool from 103 to 68 degrees F. Thus, a heated reptile can store heat and maintain a relatively high body temperature for an extended period of time.

Optimal temperatures allow efficient metabolism and immune-system activity in bearded dragons. If a dragon is kept too cool, its metabolic processes will occur at a slower rate, and the immune system will become depressed. Cool temperatures reduce digestion rate, too, which can lead to gastrointestinal problems, such as decomposition of food in the gut and bloating. The equilibria of bacteria and protozoa in the gut may also be thrown out of balance. Moreover, the rate of clearing uric acid and other compounds through the kidneys is reduced at suboptimal temperatures and the risks of kidney disease increased. Growth rate, which depends on appetite, rapid digestion, and effective metabolism, is directly affected by temperature. Therefore, keeping a bearded dragon at the correct basking and cool side temperatures results in a bright, healthy animal. Incorrect temperatures or an incorrect temperature gradient will result in sickness and ultimately death.

A cool spot, around 20 degrees F cooler than the basking area, is essential in a dragon’s enclosure.

Lighting

Good lighting is critical to the health of bearded dragons. Without it, they are less spirited, less active, and dull in color. As you probably know, even the moods of humans are affected by low light exposure. How could one expect a sun-loving animal from Australia (which is an extremely bright continent) to thrive under low light conditions? You may have seen bearded dragons in pet stores kept under low light conditions, with only a ceramic infrared heater as the primary source of heat. In addition to incandescent-type lights as heat and light sources for basking, bearded dragons need full-spectrum or high-UVB reptile bulbs provided overhead in fluorescent fixtures that run the length of the enclosure. There are new compact fluorescent-type UVB bulbs on the market. However, in our experience, the long-tube fluorescent-type UVB bulbs produce far more visual light than compact screw-in types.

We also recommend that you locate your dragon in a bright, well-lit room of the house. We have found that when bearded dragons are kept in a very bright environment, they eat better, are brighter in color, and are much more active than without bright light.

Providing UVB is critical to aiding the dragon in generating vitamins and minerals. It is hypothesized that basking lizards, such as bearded dragons, manufacture vitamin D3 when exposed to UVB radiation from sunlight. Because lizards need vitamin D3 to effectively absorb calcium, a lack of this vitamin in the diet or a lack of exposure to a UVB source can lead to calcium deficiency in the dragon. This condition becomes very noticeable in baby lizards, which require large amounts of calcium to build their rapidly growing skeletons.

A calcium deficiency in bearded dragons further results in metabolic bone disease (MBD), a crippling disease that deforms the bones, especially those in the back. To prevent MBD, provide appropriate amounts of calcium and vitamin D3 in your dragon’s diet along with exposure to UVB radiation in the form of sunlight or UVB-generating bulbs or fluorescent-type tubes.

Our observations suggest that bearded dragons do, in fact, eat more, grow faster, and remain healthier and more active when provided with sunlight or full-spectrum/reptile UVB fluorescent tubes. In one experiment, specimens that were fed ad libitum grew from hatchling to 14 inches long in fourteen weeks by combining a spotlight heat source with full-spectrum bulbs placed 6 inches above the experimental group. This group’s growth rate was significantly greater compared to specimens raised under conditions where any of three factors—light-generated heat, UVB-generating light, and food availability—were limited.

Light goes hand-in-hand with heat in providing an optimal bearded dragon environment.

Mercury vapor bulbs sold in the reptile trade fit incandescent fixtures, produce good levels of UVB, and emit heat. They are effective as a UVB source; however, you must ensure that your dragon does not become dehydrated in an enclosure with a mercury vapor bulb. We would never recommend that you use them with juvenile bearded dragons because the results are usually disastrous. There are also bulbs, such as Mega-Ray bulbs, that produce very little to no heat but do provide UVB. If you use this product, make sure to give your dragon a basking lamp for heat and also some sort of visual lighting.

One easy way to provide UVB is to expose lizards to sunlight. The safest way to expose them to sunlight is to use a screen-sided “basking cage,” which reduces the risks of overheating. A commonly used alternative is to place the bearded dragons in a large opaque or white plastic storage container with a screen top. Glass-sided, clear, or bare-floor plastic containers risk overheating and are often lethal to dragons when placed in the sun. Instead, use sand and cover part of the storage container with cardboard for shade. Even with screen-sided enclosures, you should always provide an area of shade so your bearded dragon can get out of the sun. Placement of basking cages is also important: grass and soil are safe, but beware of concrete patios or asphalt surfaces, which build up heat in the sun and can kill your dragon.

Light, Heat, and Coloration

Proper light and heat can help bring out your bearded dragon’s true colors. The bright orange-reds and yellows of certain lines of bearded dragon do not become fully expressed if temperatures are not optimal for that dragon. One or more factors related to light (and possibly heat) appear necessary to trigger the hyperxanthic response, which is an increase in yellow and orange skin pigments. This is comparable to the hypermelanistic response in humans, which is the increase of the dark pigment melanin when human skin is exposed to UV radiation from the sun. Bearded dragons raised outdoors under greenhouse plastic that filters out most of the UV radiation become just as bright as individuals kept in the open, so UV radiation may not necessarily be the triggering factor.

At Fire and Ice Dragons, we found that in indoor conditions, our bearded dragons are brightest under correct basking temperatures, very bright visual light, and Repti-Sun 10.0 fluorescent UVB tubes or Arcadia T-8s.

We also tested various types of tanks: glass tanks, top cages in various colors, wooden enclosures in various stains, all-screen cages, and enclosures with solid sides, tops, and backs. We observed how these situations affected the dragons’ coloration. Bright Super Citrus dragons that were placed in dark-stained or granite-colored enclosures darkened immediately, even with optimal basking temperature and UVB output. In screen cages, brilliant yellow Super Citrus bearded dragons dulled to gray. They were cold, and the screen blocked the visual light from the room.

Conversely, the dragons placed in all-white melamine enclosures with solid tops, sides, and backs with sliding glass doors in front were brightest in color when compared to all of the other caging systems we tested. We can only assume that the highly reflective quality of the white melamine raised the visual light within the entire enclosure. This makes sense, as Australia is a very bright continent!

Lighting helps keep a dragon’s colors rich and vivid.

Brumation (Winter Shutdown)

Once mature (after one year of age), bearded dragons usually enter a state of shutdown, commonly termed “brumation,” in which they remain relatively inactive, hidden in shelters or lying on the ground and eating little, if at all. If raised under indoor conditions, babies hatched out in the summer won’t undergo winter shutdown until the following year (at about eighteen months of age). During brumation, dragons must be maintained at cooler temperatures (60–70 degrees F), something easily achieved in most homes by placing the enclosure on the floor of a room during the winter months. Owners should decrease the wattage of basking lights to reduce the basking site’s temperature to 75–80 degrees F and leave the basking lights on for only eight to ten hours daily. Many owners are alarmed by their dragons’ drastic change in behavior during brumation and worry that their dragons may be sick. A period of brumation, however, is normal for this species. Brumation can last from a few weeks to five months. If bearded dragons are healthy, they will lose little or no weight during this period and will remain in good condition, showing no signs of disease (e.g., sunken eyes, gaping, twitching, wheezing).

There are two approaches that beardie owners can take during brumation. In the first approach, the owner can create a shutdown cycle of cooler temperatures and shorter day length, similar to what happens in the wild. The owner needs to reduce, and then eliminate, the dragon’s food about one week before the onset of cooler temperatures, allowing the dragon to empty any remaining fecal matter in its intestines. Alternatively, in the second approach, an owner can wait, observe the dragon closely, and then create brumation conditions as soon as the dragon shows signs of reduced activity and food intake.

The end of brumation is marked by a shift in behavior following the increase in heat and light that accompanies spring. At this point, the owner should return the dragon to normal conditions as soon as it starts basking and feeding again. Start with easily digestible foods, such as greens, until the dragon’s normal bodily functions return. Soaking daily will help the dragon wake up.

Bright light and heat during the day is balanced by “lights out” overnight.