Green iguanas (Iguana iguana) are a non-native species in Florida and are officially classified as invasive due to the significant harm they cause to the state’s environment, infrastructure, and economy. An invasive species is defined as one that is not native to a specific area, was introduced by human action, and causes or can cause harm to the environment, economy, or human quality of life. The prolific and widespread population of green iguanas in the state meets all of these criteria, leading to serious management concerns.
The Origin and Spread of Green Iguanas in Florida
The presence of green iguanas in Florida can be traced back to the 1960s, with their initial establishment primarily driven by the exotic pet trade. These reptiles, native to Central and South America, were imported in large numbers, often as small, attractive pets. However, as the lizards grew to their adult size of up to five to seven feet long, they became difficult to manage, leading many owners to either intentionally release them or allow them to escape into the wild.
The mild, subtropical climate of South Florida, with its year-round warm temperatures, provided an environment where these tropical reptiles could not only survive but thrive and reproduce. Unlike their native range, Florida lacks the natural predators that would typically keep their populations in check. This absence of natural controls has allowed them to spread rapidly, establishing permanent, breeding populations across the southern half of the peninsula.
Their range is concentrated along the Atlantic coast in counties like Miami-Dade, Broward, and Palm Beach, but populations have been reported as far north as the Tampa Bay area on the Gulf Coast. The extensive network of canals and levees in South Florida has provided ideal corridors for dispersal, allowing the lizards to easily move and expand their territory. Occasional accidental introductions, such as stowaways on cargo ships, also contributed to the initial populations in the Florida Keys.
Specific Environmental and Infrastructure Damage
The invasive nature of the green iguana is evident in the distinct and costly damage they inflict on both the natural and man-made elements of Florida. A significant impact comes from their voracious herbivorous diet, which targets native and ornamental plants. Iguanas consume the leaves, shoots, flowers, and fruits of a wide variety of vegetation, including popular landscaping choices like orchids, hibiscuses, and Washington fan palms.
In natural habitats, this feeding behavior is a threat to rare and endangered native flora. For example, iguana foraging has been implicated in the decline of the host plant for the federally endangered Miami blue butterfly in the Florida Keys. Furthermore, iguanas are known to occasionally prey on the eggs and young of native birds, though they are primarily plant eaters. They also compete for space by using burrows of native threatened species, such as the gopher tortoise and the Florida burrowing owl, potentially displacing these animals.
The most widespread and expensive damage is caused by the iguanas’ extensive burrowing habits, which are necessary for nesting and shelter. Female iguanas dig complex tunnel systems that can undermine sidewalks, foundations, and pool decks, causing them to collapse or crack. This burrowing is especially destructive to water control structures, eroding and destabilizing seawalls, canal banks, and dams. One incident in West Palm Beach involved iguanas contributing to a $1.8 million emergency repair bill for a dam essential to the city’s water delivery system.
Beyond property destruction, the sheer volume of iguana droppings creates a public nuisance and a health concern. Iguana feces contaminate docks, moored boats, porches, and swimming pools, carrying the risk of transmitting the infectious bacterium Salmonella to humans. The Florida Fish and Wildlife Conservation Commission (FWC) has estimated that the collective damage to infrastructure from these lizards amounts to millions of dollars.
Regulatory Status and Recommended Control Methods
The state of Florida addresses the green iguana population by classifying it as a non-native species that is not protected, except by anti-cruelty laws. This regulatory status means that private citizens are authorized and even encouraged by the FWC to remove or humanely kill iguanas on their own property year-round, without needing a special permit or hunting license, provided they have the landowner’s permission. The FWC has also added the green iguana to the Prohibited species list, which limits their possession and distribution within the state and requires permits for existing pets.
For homeowners seeking to manage iguana populations, the FWC recommends a combination of habitat modification and active removal. Habitat modification involves making the property less attractive to the lizards, such as by removing plants they prefer to eat, like hibiscus, and filling in holes or burrows to discourage nesting. Simple deterrents, like humane harassment, can also be used to discourage their presence.
When it comes to removal, trapping is a common method, but any captured iguana cannot be relocated and released elsewhere in Florida due to their invasive status. Relocation would simply move the problem to a new area. Because iguanas can be difficult to handle and aggressive, the FWC advises property owners who are not able to safely remove them to seek assistance from professional nuisance wildlife trappers. These professional services ensure the humane and legal eradication of the reptiles.