Enclosure: Temperatures & Humidity

Lighting

The most effective way to light your skink’s enclosure is with heat lamps. That way you can maintain the right temperature gradient while simulating daylight. In an average 36”x18”x18” enclosure, only 2 lamps would be required. None on the cool end, one in the middle at 75w, and one over the basking spot at 100-120w.

You can find the bulbs you need at the hardware store or pet store, but be sure to get halogen flood bulbs rather than rounded house bulbs. Halogen bulbs tend to last longer and burn hotter, so although they’re more expensive, they’re a better investment.

Since blue tongue skinks are diurnal, they do not need any kind of lighting during the night. Some people prefer red or black bulbs for providing nighttime heat, but it’s actually healthier for skinks to experience a nightly temperature drop. Before we move on to discuss specific temperatures, though, let’s talk about UVB for a minute.

UVB or No?

UVB is a type of ultraviolet radiation naturally emitted by the sun. It’s critical to helping animals’ bodies make vitamin D3. Vitamin D3 is very important for building and maintaining strong bones, especially in diurnal reptiles. Vitamin D3 deficiency leads to Metabolic Bone Disease, discussed in the Health chapter of this guide.

Blue tongue skinks’s UVB needs are not considered as urgent as that of basking lizards such as bearded dragons or uromastyx. In fact, the matter is a frequent topic of debate in the blue tongue skink community. It has been shown that BTS can be raised, bred, and maintained for decades without UVB, so technically it is not required for their survival. However, studies and veterinarians agree that dietary vitamin D3 and synthesized D3 (from UVB) are metabolized differently. Ultimately, the choice whether to provide UVB is up to you.

If you choose to provide UVB, I recommend the Zoo Med ReptiSun 10.0 High Output UVB and Arcadia Desert 12% fluorescent tubes. Mercury vapor bulbs like the Mega Ray also work well, although they produce a much narrower beam than the fluorescents. Whichever you choose, they will need to be replaced every 12 months, even if they seem to be working fine.

T8 fluorescent UVB bulbs should be installed inside the enclosure using an under-counter fluorescent fixture. These tend to be less expensive than lighting hoods and also bypass the risk of having UVB rays blocked by mesh, plastic, or glass. However, note that some skinks like to climb, so the bulb should be installed well out of his/her reach. If you are using a T5 (high output) bulb, it can be installed over mesh without adverse effect.

Temperature

Since blue tongue skinks are cold-blooded, they rely on their environment to provide the heat needed to function. The best way to achieve this is to provide a temperature gradient so the skink can self-regulate according to his/her needs. Use a temperature gun like the Etekcity Lasergrip 774 for instant, accurate information on your skink’s environment.

  • Daytime: 77° cool, 86° ambient, 95°-100° basking (25°, 30°, and 35°-38°C, respectively)
  • Nighttime: 70°-80° degrees (21°-27°C)

Use a high-wattage halogen floodlight bulb inside of a dome heat lamp with a ceramic socket to safely achieve the right basking temperatures. For an average 36″x18″x18″ enclosure, 75-100w should do the trick.

If you need a little extra warmth on the cool end, you can use a thermostat-controlled heat pad under the cage, covering no more than 1/3 of the terrarium’s floor space. Fluker’s and Ultratherm are the most popular, as well as mats designed for seed germination have also been used successfully. Avoid Zoo Med pads, as they’re too small for the advertised purpose. In terms of thermostats, The Herpstat Intro, Herpstat1, and VE-200 are all excellent quality capable of regulating multiple heat pads at once — and the price reflects that. For regulating only one heat pad at a time, Jump Start and Vivosun offer fairly reliable thermostats at a low price.

Never use a heat rock! Heat rocks are infamous for burning reptiles, so long story short: don’t do it.

Humidity

Maintaining the right humidity is important for helping your skink shed easily, as well as prevent illnesses like respiratory infections. As a general rule, Australian species thrive around 40% humidity, and Indonesian species require 60-80% humidity. However, this still varies depending on what species you have:

  • T. gigas evanescens (Merauke) — 60-80%
  • T. gigas gigas (Classic Indonesian) — 60-80%
  • T. gigas gigas (Halmahera) — 80-100%
  • T. gigas keyensis (Kei Island) — 60-80%
  • T. nigrolutea (Blotched) — 40-50%
  • T. multifasciata (Centralian) — 20-40%
  • T. occipitalis (Western) — 20-40%
  • T. scincoides chimaera (Tanimbar) — 60-80%
  • T. scincoides intermedia (Northern) — 40-60%
  • T. scincoides scincoides (Eastern) — 40-60%
  • T. rugosa (Shingleback) — 20-40%
  • T. spp. (Irian Jaya) — 60-80%

 The best way to keep track of ambient humidity is with a digital hygrometer like Zilla’s Digital Thermometer and Hygrometer.

A good rule of thumb for making sure your enclosure is humid enough is by checking your skink’s belly scales. If they’re rough, you need more moisture. If there’s nice and silky smooth and the skink is shedding well, you’re doing okay.

Tricks for maintaining humidity

Even when you use the right substrate, maintaining high levels of humidity can be tricky. Daily misting with a traditional spray bottle can give you hand cramps, so use a pressure sprayer like the Solo 418 One-Hand Pressure Sprayer to make life a lot easier. Another trick is to set aside time each week to manually mix water into the substrate until it’s damp, but not wet. While misting only touches the surface, having moisture in the substrate stabilizes humidity for longer periods of time. 

If you have a Halmahera, you may find that you still struggle to keep humidity high enough. In that case, consider investing in a fogger like the Evergreen Reptile Humidifier or Zoo Med ReptiFogger.


PRO TIP: If your basking spot has temperatures between 105-120°F, don’t worry! Even on blazing hot days in Australia, blue tongues can be found basking on hot surfaces like concrete and asphalt. As long as your other temps are looking good, your BTS will make use of that hot spot.

 

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