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Living Sanibel

By Staff | Jul 9, 2010

Green Iguana (Iguana iguana) Other names: common iguana, bamboo chicken, chicken of the tree / Status: FL=invasive, increasing, IUCN=VU / Life span: to 20 years / Length: 3.5ˆ6.5 ft. (1-2 m) / Weight: 10-20 lb. (4.5-9.1 kg.) / Nests: on island / Found: Iinterior Wetlands, Urban Areas, Gulf Beach, Mangrove Zone.

The current green iguana population on Sanibel and Captiva is a direct result of the release of this large Central and South American reptile by pet owners who no longer want the animal. After time, due in part to its long life span, the released reptiles find each other and propagate. Because of its size and ability to adapt to the climate and vegetation of the islands, a species like the green iguana can quickly get out of control.

On Gasparilla Island, approximately 25 miles north of Sanibel, the equally invasive and far more damaging spiny-tailed iguana has become a major concern to both environmentalists and residents. Unlike the green iguana of Sanibel and Captiva, which is an herbivore, the spiny-tailed iguana is an omnivore that eats not only native vegetation but also local birds, marsh rabbits, green anoles, young gopher tortoises, and snakes. Since 2006, Lee County has spent an average of $100,000 a year in an attempt to eradicate this invasive species from Gasparilla. To date, nearly 10,000 spiny-tailed iguanas have been caught and euthanized, mostly from the northern end of the island. The sheer numbers of these lizards, coupled with their high fecundity, make their removal a daunting and expensive task.

Echoing this program, the city of Sanibel has undertaken a green iguana eradication program on the islands. To date it has captured and euthanized more than 750 iguanas at a cost in excess of $50,000. Although nowhere near as devastating to wildlife as the spiny-tailed iguana, this huge lizard destroys ornamental vegetation, eating shrubs, orchids, fruits, mangoes, berries, and tomatoes. It also digs nesting burrows that can undermine sidewalks, seawalls, and foundations. It often leaves droppings in private swimming pools and is known to harbor salmonella bacteria.

The green iguana’s high reproductive rate makes its eradication difficult. A single clutch can contain as many as 65 eggs. With the destruction of so many of the island’s alligators after the death of an island resident in 2004, the green iguana has no natural predators other than bobcats to keep its population in check. Although South Florida represents the northernmost part of its range, the iguana appears to be undergoing a process of natural selection. The more cold-tolerant members of the species are surviving, while the others die off during the winter. Eventually, the cold-resistant iguanas will continue to move northward, possibly as far as central Florida. Thus far, it has not been able to survive a hard freeze.

In Central and South America many people eat the green iguana. The level of harvest in some areas has become so severe that the ICUN is considering listing it as an endangered species. It is said to taste like chicken, especially when fried; hence, the nickname chicken of the tree.

Look for this exotic lizard in and around Beachview Country Club where the population is flourishing. If you see one, or a nesting female, report the sighting to the Sanibel Natural Resources Division at 472-3700, or keep the animal in sight and call the Sanibel Police Department at its non-emergency number, 472-3111. Do not attempt to kill or capture an iguana as it has sharp teeth and can deliver a nasty bite.