How to keep...

Large lizards from tropical America:

Green Iguanas, Ctenosaurs and Basilisks

John Boonman

introduction

The tropical areas of Central and South America house numerous species of large lizards, some of which are regularly kept in captivity. One of the two species of Green Iguana (Iguana iguana) often appears in pet shops and captive-bred hatchlings can also be frequently seen. Periodically, one of the 13 species of Spiny-tailed Iguanas appears in stores (Ctenosaura similis), whereas captive-bred animals of several others species can often be purchased at individual breeders (notably Ctenosaura melanosterna). Two out of four species of the genus Basiliscus are rather popular among amateur herpetologists (Basiliscus plumifrons and Basiliscus vittatus). The animals presented here vary in total length from 30 cm for the smallest of the Ctenosaurs, to 1.5 m for Green Iguanas. Basilisks and the larger Black Iguanas are intermediate in length.

KEEPING IN CAPTIVITY

Large lizards need a lot of space, even though they are neither very busy nor very motile animals. A 2x1x2 m (lxwxh) housing is required for adult Green Iguanas. An adult would be from two years of age and up, but remember that they grow extremely fast. Small and young animals prefer a housing that is not too big. Tree dwelling species need numerous climbing facilities as well as various horizontal basking places; the animals need to be able to choose between different sites. Many species of Black Iguanas, especially the smaller ones, prefer shelters that fit them tightly such as hollow trunks or tubes.

A detailed furnishing of the enclosure is of less importance. In nature the animals live in various habitats, ranging from tropical rain forest to bare, solitary trees in savannah like environments. A high relative humidity is not required however it will often improve the lizard's shedding. A water bowl might make a convenient addition as many animals release their feces over water. The floor must be covered with either smooth material (concrete or linoleum) that can easily be cleaned or loose material (peat dust, wood shavings or eventually newspaper). Never use coarse or sharp pellets (coarse sand, pebbles or backed clay beads). Animals will eat them and eventually die of constipation.

Heat/Light

Cold-blooded animals from the Tropics need a lot of heat but the general environmental temperature need not be exaggerated (around 25°

Ultraviolet light is advisable in order to provide the animals with the essential vitamin D. Sunlight, not filtered through glass is the most suitable source however it can rarely be maintained in the Netherlands for a substantial period of time. It is therefore necessary to use lamps. UV-radiators with proven efficacy include halogen lamps (used in construction areas with the protection glass removed) and Ultra-Vitalux lamps. New types that may be useful appear regularly. Never use lamps that emit UV-light of short wavelength like the ones used to kill bacteria.

FEED

In nature Green Iguanas are vegetarian and they consume primarily leaves and flowers. Black Iguanas predominantly eat vegetarian matter too, but they are better equipped to catch living prey and they do. Basilisks almost exclusively eat living feed although sometimes they are willing to take dead meat.

An appropriate diet for both Green and Black Iguanas consists of various leafy vegetables, notably: collard and turnip greens, Chinese cabbage, bok choy, watercress and endives. Suitable herbs include dandelion (flowers as well), sorrel, nettle, plantain, bindweed and grape leaves. All kinds of fruits can be offered too (albeit limited since the calcium to phosphorous ratio is not optimal). The fruits of choice are papaya, citrus and fresh figs. Flowers can stand on the menu as well, primarily (red) hibiscus, dandelion and rapeseed.

Although Green Iguanas do like meat it should be advised not to serve it, especially not to older (over two years of age), non-pregnant animals. Their kidneys can not stand large amounts of protein. Protein-rich vegetarian material is the best diet for them. These limitations do not hold for Black Iguanas to the same extent. Without a doubt, they can handle more protein. Basilisks are adapted to a higher protein diet and can be fed with insects, morioworms, earthworms or mice.

Vitamins and calcium should be offered regularly (depending on the menu). Water-soluble vitamin D3 (Davitamon aquosum) is the most obvious additive, just like calcium lactate or any other water-soluble calcium salt. Other useful preparations are Gistocal, Sporavit or Carmix (meant for carnivores).

SOCIAL RELATIONSHIPS

Little is known about these lizards' social relationships. Basilisks and Black Iguanas are territorial so it will be practically impossible to house more than one male. More than one male Green Iguana may be housed together but it will not be possible in all cases. Newly born hatchlings need a group to secure a balanced development in the first months of their lives.

DISEASES

Most of the diseases found in these lizards are caused by malnutrition. Insufficient calcium, an unbalanced calcium/phosphorous ratio or too little vitamin D (UV-light shortage) are often the cause of this malnutrition. Bad bone development, deformations and general weakness are the consequences. Egg binding can often be attributed to a lack of calcium in the feed. These kinds of diseases are easy to cure by means of appropriate feeding. Stress is very common in animals captured in the wild or those that are otherwise maltreated. Traumas such as this are often hard to treat. Rest, space and other optimal circumstances are the only possibilities. Both Green and Black Iguanas are vulnerable to mites. Treatment with appropriate preparations can bring relief.

Woundings caused by incorrect social relationships (see above) may occur and can only be prevented by removing or separating animals or adapting the housing by adding more space or hiding places.

INFORMATION

Melissa Kaplan's Giant Green Iguana Information Collection http://www.sonic.net/~melissk/ig_care.html

LITERATURE

Köhler, G., 1993. Basilisken, Freilandbeobachtungen, Pflege und Zucht. Verlag Gunther Köhler, Hanau. ISBN 3-9802892-2-2

Köhler, G., 1998. Der Grüne Leguan. Biologie, Pflege, Zucht, Erkrankungen. 3. Auflage. Herpeton Verlag, Offenbach. ISBN 3-9802892-9-X.