Green Iguana Care
Dr. Jenni Bass
Temperature range: 80 to 100 degrees Fahrenheit (25 to 38.5 degrees Celsius) 24 hours a day. Ideally, maintain the cage at the cooler end of this range during the night and at the warmer end during the day. This is made easier by using a thermostat. We recommend secondary or background heating of the whole cage, with a range, for example of 80 to 95 F, and provision of a basking or spotlight to create a hotspot of 95 to 100 F, during the day.
Enclosure, Lighting and Heating
Any reptile enclosure should be easy to clean, well ventilated, properly lit and adequately heated. The cage must be escape proof and secure from interference by children and other animals. Glass aquaria and terraria can be suitable enclosures for smaller iguanas. For larger lizards, well-ventilated polyurethane-coated wood, plastic, Formica, or Plexiglas cages are more suitable. Greenhouses may work where the climate is suitable. Sometimes with the appropriate modifications, it is possible to devote a spare room or a large closet to housing an iguana.
Particularly for the bigger lizards, the cage design should be vertical, rather than horizontal, as iguanas like to climb and lounge on branches. Diagonal and horizontal perches are recommended, and these should be at least the diameter of the iguana's body. For a large iguana, an enclosure of at least 8 by 4 by 8 feet high is recommended. The horizontal dimensions of the enclosure must be sufficient to allow the animal to stretch out and to move freely. Always provide visual barriers: reptiles do not like to live in a fish bowl.
Regardless of size, an iguana's enclosure needs to meet the following criteria:
Ultraviolet light source: 10 to 12 hours in each 24- hour period. A regular photoperiod or day/night cycle is crucial to the mental and physical well being of reptiles. An automatic timer is recommended.
Humidity: 80 to 90 percent relative humidity . A humid environment must not be achieved at the expense of good ventilation. Bathing, misting, drip systems and humidifiers can be used.
Good ventilation: Fans such as those designed for bathrooms may be necessary in large or solid sided enclosures. These fans need to be shielded from contact with the iguana.
Heat sources can include heat lamps (infrared, ceramic), heat tape and undertank heaters. It also helps to keep the animal in a warm room. This is secondary heat. Heat must be present 24 hours a day, but white light should not be left on for more than 12 hours. It is recommended that the entire enclosure be heated to within the POTZ with, for example, a ceramic heater, which emits heat but no light, and adding a basking heat source, such as a spotlight focused on a small area, to provide an area at the upper end of the POTZ. Installing the radiant heat source (spotlight) at one end of the enclosure provides a temperature gradient. As iguanas should have approximately 12 hours of daylight and 12 hours of darkness, having the spotlight on a timer will accomplish the goals of a regular photoperiod and of decreasing the cage temperature slightly at night.
To prevent burns, be sure that the iguana cannot come into contact with any light or heat bulb. Heat lamps must be screened. Hot rocks are not recommended. These heat irregularly, and commonly cause burns. A hot rock does not heat lizards of any size adequately and since the rocks do not radiate heat significantly, they are not appropriate for basking lizards, such as iguanas. Iguanas have evolved to absorb heat from a radiant overhead source, that is, the sun.
No place in the cage should be cold. Sick lizards often hide, and if the hiding spot is not within the POTZ, the animal's immune system will not function properly. Use a thermometer to check temperatures, not just in the hot spot, but also in shaded or cooler areas. Ideally, place several thermometers about the enclosure. Do not use your hand to estimate the temperature. "Warm" is too unreliable. Use a thermometer. A hygrometer, a device that measures humidity is another important tool. These can be bought at hardware stores.
Ultraviolet light in conjunction with an appropriate environmental temperature and diet is essential to iguanas. Ultraviolet light should be provided daily for 10 to 12 hours. Some lights are marketed as full spectrum, but do not necessarily emit the correct wavelengths of light. A light should meet the following criteria: CRI (color rendering index) of 90 to 100, and CTI (color temperature index) of greater than 5500 K. Lights recommended include Duratest Vitalite® and Vitalite Plus®, Black Light Fluorescent®, Reptisun® and Iguana Light®. Some lights, although they meet the UV requirements, do not emit natural looking light. None of these lights approaches natural sunlight, in terms of the UVB output and the psychological importance of proper lighting. An individual animal may benefit from a combination of lights. As long as the UV requirements are met, additional lights may be added to improve appetite and behavior.
Since reptilian eyes may see parts of the spectrum that we do not, natural light may be necessary for the environment, food and other reptiles to appear as they should to an iguana. Lighting may also affect the behavior of the animals and in addition to improving their psychological well being, correct light will help to display the animal at its best. Always use the longest tube light you can. A four foot light emits more than twice the UVB rays of a two foot light.
Ultraviolet rays do not penetrate glass or plastic, so to be effective the light, whether natural or artificial, must shine directly on the animal. For the iguana to receive the maximum benefit from UV light, it should be fixed 18 to 24 inches from the basking spot. In larger enclosures, this may be managed by fixing the light vertically or by using more than one light. When the animal can be kept with in the POTZ, sunlight is tremendously beneficial.
When the temperature outside is appropriate (80 to 95 F), expose your iguana to sunlight, either through a screened window or in a secure enclosure outside (provide ventilation, shade, shelter and water). Never place an iguana is a glass or plastic container in direct sun, as the enclosure can reach dangerous temperatures in as little as 5 to 10 minutes. Remember that to be effective in vitamin D and calcium metabolism, not only must the UV rays be present, but the animal must be within its POTZ. Be aware that reptiles, when exposed to natural sunlight, will often undergo dramatic changes in behavior, becoming very active, and sometimes changing color or becoming aggressive.