Green Iguana

Primarily a tree-dwelling reptile, the green iguana is a specialised leaf-eater, consuming the tender green leaves and flowers of a selection of trees, shrubs and herb vegetation. For over 90 percent of the time, green iguanas are inactive and often when they do move, they travel slowly. However, if required, green iguanas are capable of running fast and will dive into water to escape predators, revealing their excellent swimming abilities. This explains the iguana’s preference for habitat close to watercourses.

Green iguanas are territorial during the breeding season, and will defend their home range against intruders. If a green iguana ventures into the territory of another it will be met firstly with pronounced head-nodding behaviour, believed to be an intimidating action. This may be followed by an extensive threat ritual, when the iguanas vertically flatten their bodies and erect their dorsal crests to create the appearance of being much larger. If the altercation does not end there, serious fights with injuries can follow. The dewlap, which can be lowered by a bone in the neck, is also used in threat displays, as well as for communicating with other green iguanas.

Green iguanas breed during the dry season, during which time a territorial male occupies his territory with several females (4). A month or two after mating, the females move to communal nesting sites where they lay a clutch of 17 to 76 eggs in burrows dug into the ground. Iguana hatchlings emerge from the nest after three months of incubation, coinciding with the onset of the rainy season, a strategy to ensure plentiful, lush, green vegetation for the growing iguanas to feed on. Green iguana hatchlings are incredibly vulnerable to predators, including other reptiles, birds and mammals, and only about 2.6 percent live to the age of one year. Sexual maturity is reached after two to three years.

## Description

The green iguana is one of the best-known reptiles due to its popularity in zoos and with private reptile keepers. It has a very distinctive appearance, with a large head, a pronounced dewlap, and an impressive crest of comb-like spines that runs down the centre of the back and tail, measuring around three centimetres high. While, like its name suggests, this iguana is usually a shade of green, (from dull, grassy green to vivid turquoise), bright orange individuals may occur in the northern parts of its range, and the colour may also vary with temperature, particularly when young, being bright green when hot and dull and dark when cold. The green iguana’s scaly skin is either uniformly coloured, or bears blackish stripes or a contrasting brownish pattern. Prominent large, circular scales are present on the lower jaw below the clearly visible tympanum. Male green iguanas can be distinguished from females by the more pronounced spiny crest and larger head, the more noticeable femoral pores, and the broader cloaca opening.

## Behavior

hen frightened by a predator, green iguanas will attempt to flee, and if near a body of water, they dive into it and swim away. If cornered by a threat, the green iguana will extend and display the dewlap under its neck, stiffen and puff up its body, hiss, and bob its head at the aggressor. If threat persists the iguana can lash with its tail, bite and use its claws in defense. The wounded are more inclined to fight than uninjured prey.

Green iguanas use "head bobs" and dewlaps in a variety of ways in social interactions, such as greeting another iguana or to court a possible mate. The frequency and number of head bobs have particular meanings to other iguanas. Green iguanas are hunted by predatory birds and their fear of these is exploited as a ploy to catch them in the wild. The sound of a hawk's whistle or scream makes the iguana freeze and it becomes easier to capture.

## Diet

Green Iguanas are primarily herbivores, with captives feeding on leaves such as turnip greens, mustard greens, dandelion greens, flowers, fruit, and growing shoots of upwards of 100 different species of plant. In Panama one of the green iguana's favorite foods is wild plum, *Spondias mombin*.

Although they will consume a wide variety of foods if offered, green iguanas are naturally herbivorous and require a precise ratio of minerals (2 to 1 calciumto phosphorus) in their diet. It is important for captive iguanas to have a variety of leafy greens along with fruits and vegetables such as turnip greens, collards, butternut squash, acorn squash, mango,and parsnip. Juvenile iguanas often eat feces from adults in order to acquire the essential microflorato digest their low-quality and hard-to-process vegetarian-only diet.

There is some debate as to whether captive green iguanas should be fed animal protein. There is evidence of wild iguanas eating grasshoppers and tree snails, usually as a byproduct of eating plant material. Wild adult green iguanas have been observed eating birds' eggs. Zoologists, such as Adam Britton, believe that such a diet containing protein is unhealthy for the animal's digestive system resulting in severe long-term health damage including kidney failure and leading to premature death. On the other side of the argument is that green iguanas at the Miami Seaquarium in Key Biscayne, Florida, have been observed eating dead fish and individuals kept in captivity have been known to eat mice without any ill effects. De Vosjoli writes that captive animals have been known to survive and thrive on eating nothing but whole rodent block, or monkey chow, and one instance of romaine lettuce with vitamin and calcium supplements. However, it is only recommended that captive iguanas not be fed lettuce or meat, and instead receive the vitamins and minerals they need via a purely herbivore diet.

## Range and Habitat

The green iguana has a wide distribution ranging from the Mexican states of Sinaloa and Veracruz, through Central America and into South America as far south as Peru, Paraguay and northern Argentina, including many neotropical islands. Green iguanas most commonly inhabit tropical forest close to water, from sea level up to an altitude of 1,000 meters, although they avoid areas of deep forest where the sun cannot reach the ground to incubate the nest.