Tortoise Adoption Program
Appendix II: Artificial Lightning
Care, Husbandry and Diet of the Desert Tortoise
Ultraviolet radiation derived in nature from sunlight has long been recognized as essential for the synthesis of vitamin D in many organisms. Vitamin D3 is essential for the assimilation of calcium and phosphorus from the diet. Artificial full spectrum lighting appears to meet minimum ultraviolet radiation requirements for many reptiles kept indoors. It is not, however, generally recommended for maintenance of desert tortoises in Arizona. There is no safe comparable substitute for natural sunlight. Artificial lighting may, however, be useful in some circumstances where juveniles must be kept indoors temporarily or intermittently. Therefore the following information is provided.
The safest lighting configuration incorporates a 24" or 48" fluorescent shop light fixture holding two ZooMed Reptisun (5.0) fluorescent bulbs or one UV transmitting fluorescent tube (ZooMed Reptisun, Vita-lite or GE Chroma 50 bulbs are acceptable) and one BL-type blacklight fluorescent tube. The blacklight must be the BL type and NOT the BLB type. The lighting unit is situated from 4" to 15" above the animal. A clip-on incandescent lighting fixture is generally used with the fluorescent fixture to heat the area up to ~85°F (29°C) beneath the full spectrum lighting. This provides the natural combination of bright UV-rich light and warmth which many ectothermic (cold-blooded) animals seek and require. The wattage of the heating lamp is determined by the size of the enclosure and the distance it is installed from the substrate. A hide-box should be provided on the coolest end of the enclosure allowing the animal to retreat from the light and heat. Heat tolerance limits of the tortoise must be accommodated at all times. Both lighting units may be controlled by an electrical timer to insure a normal day/night cycle. Tortoises do well under an 11 hour day/13 hour night summer cycle. A period of darkness is essential. Lights should never be left on 24 hours a day.
There is an approximately 50% loss in UV efficiency for every foot the lights are raised above the substrate. Also, the UV output with time. Reptisun bulbs should be changed every 8-10 months and other UV fluorescent bulbs should be changed every six months to maintain optimal UV output. Reptisun bulbs are produced by ZooMed Laboratories. Blacklights are manufactured by: General Electric (models F20T12-BL [20 watts] and F40 BL [40 watts]); Westinghouse (models 20T-12 BL [20 watts] and F40 BL [40 Watts]). The Vita-Lite is manufactured only by DuroTest, North Bergen, New Jersey. Other full spectrum lighting of comparable quality are the Westinghouse "Colortone 50" or the General Electric Chroma 50 (or Chroma 70).
Another alternative is to use the 'Wonderlite', produced by the Public Service Lamp Corp., 410 West 16th Street, New York, N.Y. 10011/Tel. 1-800-221-4392. These 160 or 300watt, reflector flood lights, are self-ballasted mercury vapor lamps that can provide both heat and ultra-violet light (even beyond the distance that limits the use of fluorescent lamps). This allows the lamp to be moved closer or further from the basking area to adjust temperature without impairing its use a source of UV light.