Description
The green iguana is one of the largest lizards present in the United States. Adult males can grow up to 6 feet long and weigh as much as 17.5 pounds, but normally are 9-12 lbs. A crest of large spines along the back and tail along with a large dewlap under the chin help identify this strikingly-green species. Confusingly, the Green Iguana may be brown, gray, black or dark green. The males turn orange when they are mating. Hatchlings and juveniles are bright green, and adults have black bands on their sides and tails.
Ecological Threat
Due to the larger size, high fecundity and population numbers, Iguana iguana has become a nuisance. For Puerto Rico, the iguanas overrun the island, quickly displacing native herbivores, invading natural rainforests and destroying backyards and gardens. This is also a concern for Florida because of their strong presence in the Everglades and their ability to push out native lizards and insects. Specifically, the Miami blue butterfly (Cyclargus thomasi bethunebakeri) is not able to re-colonize in the Florida Keys because the Green Iguanas are eating all the host plants the butterflies need to lay their eggs. Also, have been observed using the burrows of the Florida Burrowing Owl, a species of special concern, all of which can make them more of a serious threat to Florida’s ecosystem than originally believed. Thankfully, Green Iguanas are intolerant to cold temperatures. Populations in Florida have been reduced from unexpected freezes, and perhaps a similar scenario occurs in South Texas.
Biology
Iguanas tend to be arboreal and prefer large trees overhanging water, into which they dive to escape predators. Green iguanas are herbivores that feed on leaves, fruits and flowers. Juveniles will eat insects in addition to plant food. Preferred plants are hibiscus, orchids, roses, garden greens, squashes and melons. They breed during the dry season and 65 days after mating females burrow up to 3 feet deep. Over 3 days deposit 20-70 eggs in the burrow and the eggs hatch during the wet season. The juveniles become sexually mature in3 to 4 years and will live several years after maturity. They have been known to live up to 20 years.
History
Popular as pets, green iguanas have spread to the United States through this trade. Iguanas can grow very large and ornery, to where they bite and whip their tails at their owners. This behavior causes them to be released into the wild. They were first reported outside of captivity in Miami, Florida in 1966 and are now overrunning the Everglades. In Texas, they slowly worked their way up from Southern Mexico to Southern Texas, where they have been established at least since the 1990s. Luckily, expansion further North in Texas is unlikely due to irregular freezes, but with warmer temperature trends anything could happen. For Puerto Rico iguanas have completely overrun the island and are a major pest.
