Enclosure models designed using Sketchup in browser, 2018.
Enclosure Design
Location
This enclosure is designed to exist within a tropical zoo in temperate regions. Here it would be most suitably positioned within a tropical house to maintain maximum control over the conditions experienced by the iguana. Although the following recommendations include specified dimensions, zoos holding green iguana are limited in available space, particularly when enclosures are within other buildings such as tropical houses, this could mean that individual enclosures may suffer from smaller dimensions than are recommended, potentially having an impact on the animal's well being.
Dimensions
For enclosures containing only one or two green iguanas, the total enclosure floor space should be at least 2.5 times the total length of the largest iguana squared. The maximum length is usually approximately 2 meters, the floor should therefore be a minimum of 5 meters squared. The height, on the other hand, should be at least 4 times the snout-vent length, this is approximately 60cm , therefore giving an enclosure height of at least 2.4 meters. For each additional iguana after this the space should be increased by 10% (Dowling 2008).
Behaviour
All animals being kept in zoo collections should be allowed the opportunities to express their natural behaviours (EAZA 2014). In the case of the arboreal green iguana (Gleeson et al. 1980) this primarily takes the form of locomotion in foraging for food, mating purposes, or thermoregulation (Krysko et al. 2007, McGinnis and Brown 1966, van Marken Lichtenbelt et al., 1993). To accommodate for this, the enclosure should contain a basking area (Dowling 2008), such as the one shown in figure 1, stone and vegetation should also present to help simulate their natural environment. The stones have the additional health benefit of wearing down the iguana's claws which would otherwise need to be more heavily monitored and clipped (Dowling 2008). Additionally, the interior walls of the enclosure can be painted in greens and browns to help mimic the iguanas natural canopy habitat, giving the potential to help minimise stress to the animal as per EAZA's (2014) guidelines, while also giving the enclosure a more pleasing aesthetic for the public to view.
Figure 1: Basking area and feeding station
Figure 2 shows a representation of the branches that would be implemented as the green iguana is arboreal in nature (Gleeson et al. 1980) and therefore needs to be provided climbing opportunities. Vegetation should also be implemented throughout the enclosure to provide privacy to the animals and options for hiding from the public (Dowling 2008).
As iguanas explore their environment using their tongues, the use of fine substrates is not advised for coating the floor space, instead, carpet should be used, this avoids opportunities for health complications, and the iguanas will spend majority of their time above ground level (Dowling 2008).
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When breeding the iguanas, space will be needed for the female to lay her eggs. This could be in the form of deep soil (figure 2) or a nest box (figure 3) containing newspaper with non-toxic ink (Dowling 2008). Which ever option is used, keepers should ensure they can easily access the eggs to take for incubation to maximise the breeding success of their animals.
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Animals in captivity should never be exposed to unnecessary stress (EAZA 2014), as such, keeper entrances to the enclosure should be kept as close to the feeding area as possible, as shown in figure 1, where the dips in the basking platform represent nichés in which food and water dishes may be placed without the animal being able to swipe them to the floor.
Figure 2: Branches, stone, soil and carpet.
Figure 3: Nest Box.
Iguana Health
The green iguana, like other reptiles needs to bask in UVB light in order to be able to produce vitamin D (Allen et al. 1998), as such, above the basking platform a heat lamp that emits UVB should be affixed to the ceiling of the enclosure. This heat lamp should be warm enough to allow the iguanas to reach a temperature of approximately 36.6°C, while refuges in the enclosure should allow them to cool to around 32.9°C as this is the temperature range they have been found to thermoregulate at in the wild (van Marken Lichtenbelt, 1997). Digital thermometers with displays external to, or just inside of the door or window of the enclosure should be used to monitor temperatures. Additionally, ventilation hatches could be incorporated such as the ones exemplified in figure 4 above the main enclosure space as well as the nest box. This can allow the keepers some manual control over the temperatures within the enclosure if the space gets too hot throughout.
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With food being presented to this animal on a daily basis, two bowls could be used, the one not in use on a particular day can be throughly washed, using highly diluted detergent. Similarly, the water bowl can be cleaned the same way, but weekly, or as water is needed (Dowling 2008). The contents and walls of the enclosure and glass screen through which visitors can observe the animal should also be cleaned a minimum of once per week, also with diluted detergent to ensure the iguana cannot be poisoned by the fluid used (Dowling 2008).
Figure 4: Ventilation
Keeper Health
In addition to the risk of contracting disease such as Salmonella (Ebani and Fracino 2006), the green iguana could potentially cause physical harm to their keepers, though they are usually of good temperament and tend not to do so intentionally.
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To avoid risking contraction of any disease from the animal, direct contact should be avoided unless absolutely necessary. When it is necessary, hands must be thoroughly washed afterwards, however, the enclosure should have a pair of gloves stored beside the enclosure (Dowling 2008), such as in the box in figure 5.
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The gloves used should always be thick enough to withstand the iguana's claws as not only can they inflict wounds, but the opening of a wound can allow immediate introduction of pathogens from the animal into the keeper's bloodstream (Dowling 2008).
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Goggles should also be readily accessible as the whipping action of the iguana's tail is capable of causing major damage to the eyes (Dowling 2008).
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Figure 5: Rear view of the enclosure.
Accessibility
At the rear of the enclosure there should be a keeper-access door to allow the keeper to enter the exhibit to present the animal with food and water, allow entry for cleaning purposes and allow room for transport containers to be brought in or out while introducing animals to or removing them from the exhibit (Dowling 2008).
Whilst the enclosure must contain a sufficient level of complexity (AZA 2018) for the green iguana, the vegetation, branches and furniture should not inhibit the keepers ability to access all parts of the exhibit, as such it may be advisable to ensure a 'safe' path is available, and that the keepers are trained and aware of where this is.
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Similarly, visitor 'accessibility' is also important. Although the incorporated vegetation may be used to form refuges for the iguana, it should not prevent the public from having the opportunity to see the animal, as such areas such as the basking platform should not be as densely vegetated.
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