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Practical notes on creating humid tropical vivaria for tortoises and turtles

Andy C. Highfield

The depth and type of substrate is critical in tropical and humid type terraria. We have had good results with a mixture of fibrous peat-type composts, soft sand, leaf litter and mulched orchid or cypress bark. This will need changing regularly, although the larger the area involved the less frequent complete changes will be required. The substrate should be as deep as possible, or, as a minimum, a 75 mm (3") layer should be used for average-sized tortoises. Species which require very high humidity levels and damp substrates, should be provided with an additional layer of sphagnum moss on top of the substrate described above.

Nothing helps to improve the appearance of an area more than carefully selected plants. Banana plants are an obvious choice for larger or medium-sized areas. Tropical ferns are also excellent choices. Plants not only provide essential shade, they also help considerably in raising the ambient humidity within the terrarium.

Most tropical or rain-forest species do not require high levels of illumination. They also do not have a requirement for high output UV-B tubes, as these species, for the most part, obtain much (or all) of their D3 from their food. The vast majority of rain-forest type habitat tortoises and turtles are omnivorous, rather than strictly herbivorous, and the animal-derived part of their diet typically contains pre-formed D3. This is very similar to the situation with snakes, which also do not require UV-B to synthesise D3 for the same reason. Herbivorous tortoises and lizards, by comparison, must synthesise their entire D3 requirement from sunlight. As direct, high intensity unfiltered sunlight is a scare commodity in dense tropical forests, it therefore is hardly surprising that we do not find many strictly herbivorous tortoises or lizards in such environments.

Virtually all tropical forest inhabitants require high levels of humidity. In captivity, this can prove problematic and normally entails use of an enclosed terrarium. Some methods of maintaining humidity are described below:

Horticultural sprayer: These can prove very effective, but require personal intervention on a regular basis. For single tanks or small areas they are convenient and cost-effective.

Automatic misting system: These can be constructed from commonly available horticultural supplies, such as the attachments sold to accompany drip irrigation systems. A reservoir to hold tepid water is required - I recommend a 20 gallon plastic tank with a submersible 100W aquarium heater. Water can be circulated to the misting heads using a 12 volt automobile screen washer pump, or by adapting a submersible canister filter from a tropical fish tank. A time switch or humidity sensor (again, available via horticultural suppliers as an "electric leaf" sensor) will complete a fully automatic and highly effective system.

Ultrasonic humidifier: These units are especially suitable for the smaller-sized vivarium, and are popular with keepers of tree frogs and similar amphibians. There are reports of reliability problems with cheap brands, so it is best to obtain the best quality you can afford.

With care, a highly functional humid terrarium can be designed which will greatly improve the quality of life of all turtles which require such an environment.