Iguana

## Take a closer look...

Iguanas are some of the largest lizards found in the Americas, with their whiplike tail making up about half of that length. Like other reptiles, iguanas are cold-blooded, egg-laying animals with an excellent ability to adapt to their environment. Iguana species vary greatly in size, color, behavior, and their endangered status in the wild. Some species, like the green iguana, are quite common; others, like Fiji’s banded iguanas, are endangered.

## An adaptive nature

Different iguana species look and act so differently, you might not recognize them as members of the same family. While some iguanas have colors that are vivid and bright, others have rather dull colors. Because iguanas can be found in a variety of habitats, each species has its own unique adaptations. The marine iguana of the Galápagos Islands is a skillful swimmer, and its black coloration helps it to warm its body after swimming in the cold ocean.

In contrast, the green iguana is at home high in the trees of a tropical rain forest, while still other iguana species have adaptations that allow them to live successfully in the dry, hot desert or rocky areas.

## The dinner bell

Most iguanas are herbivores, eating fruits, flower buds, and young leaves. Some species also eat the occasional juicy mealworm or wax worm! The marine iguana dives in the ocean to scrape algae from rocks.

At the San Diego Zoo and San Diego Zoo Safari Park, our iguanas are offered a fruit salad that includes dark leafy greens and a variety of fruits, while some species also receive crickets, mealworms, and wax worms. But because wax worms are high in fat, they are considered the “dessert” part of the menu!

## Or someone’s dinner

Speaking of food, iguanas themselves are eaten by a variety of natural predators—hawks, owls, snakes—and humans. Green iguanas are bred and raised on farms in Central and South America to be eaten by people. Young iguanas are particularly vulnerable to predation by feral cats, and no iguana is safe from a pack of dogs. The iguana’s whiplike tail can be used for defense, and many species have tails with sharp “spines” that pack an extra “punch.”

## Smack talk

Most male iguanas are extremely territorial, fighting viciously with any other males that venture into their domain. The most dominant males have the highest testosterone levels and are larger in body and head size. They also possess more active scent glands than lower-ranking males, which do not defend territories but move between the territories of dominant males.

To intimidate intruders, Fiji’s banded iguanas darken their green coloration to make the lighter banding on their body stand out, and they erect their crest and dewlap to look larger and more threatening. The exception is the marine iguanas, which sleep or sunbathe in large groups without conflict.

A series of head bobs may be used as a threat display—called “iguana smack talk” by our keepers. Mouth gaping and push-up behaviors are also used to indicate dominance. A male courts a female with gentle nudges and head nods. A male with long, erect spines and extended dewlap, which make his head appear larger, are features that attract females. Battered and chewed spines indicate a male with a low position in the mating hierarchy.

## No mama for the baby iguana

The females of most iguana species dig a burrow in a sunny area, lay their eggs inside, cover them, and then leave the eggs alone. Even arboreal iguana species leave the trees to lay their eggs. The temperature in the burrow stays a fairly constant 77 to 89 degrees Fahrenheit (25 to 32 degrees Celsius). The warm temperature incubates the eggs. All eggs in a nest usually hatch at the same time, and the young dig out of the burrow without help from the parents. On their own, iguana hatchlings face many dangers.

## Iguanas in Fiji

With an emerald green body and bands of white or blue, more prominent on the males, Fiji’s three known iguana species inhabit a multitude of habitats, from coastal swaps and lowland forests to rain forests on Fiji’s volcanic slopes. Highly arboreal, they have long toes with sharp claws and long tails for balance in the treetops. Rarely seen on the ground, banded iguanas move from tree to tree by using the overlapping branches. They are omnivorous, feeding on leaves, flowers, fruits, and small insects.

Adult banded iguanas may reach 21 inches long—more than half of which is the tail. When fully mature, they weigh between 3.5 and 7 ounces, and males tend to be larger and heavier than females.

## Rock iguanas in the Caribbean

The Caribbean islands are rich in reptiles, with more than 500 reptile species, 94 percent of which are found nowhere else on Earth. Several iguana species are known collectively as rock iguanas, and some are found on just one or two islands. Female rock iguanas lay a clutch of 5 to 20 relatively large eggs each year; the larger eggs result in large hatchlings that evolved in response to the lack of native predators. Unlike their mainland counterparts, such as green iguanas, the island dwelling iguanas did not need to produce a lot of offspring as a hedge against predators.

The smallest of the rock iguana group are the Turks and Caicos iguanas. All eat a wide variety of fruits and serve as important seed dispersers for many native plants.