Iguanas are an established invasive species in Florida, primarily the Green Iguana (Iguana iguana) and the Black Spinytail Iguana (Ctenosaura similis). An invasive species is defined as a non-native organism whose introduction causes or is likely to cause economic or environmental harm, or harm to human health. These large reptiles have proliferated throughout the state, particularly in the southern and central regions, due to the favorable climate and lack of natural population controls. Their establishment has created significant management challenges for the Florida Fish and Wildlife Conservation Commission (FWC) and property owners.
How Iguanas Became Established in Florida
The iguana population explosion in Florida stems from the exotic pet trade that flourished in the mid-20th century. Green iguanas, native to Central and South America and parts of the Caribbean, were first reported in the state in the 1960s when they were popular pets. Many owners were unprepared for the reptiles’ large adult size and either intentionally released them or allowed them to escape captivity. This established the initial breeding populations, which quickly found the South Florida environment highly hospitable.
Florida’s subtropical climate mimics the reptiles’ native tropical range, allowing them to thrive and reproduce year-round. The urban and suburban landscapes of counties like Miami-Dade, Broward, and Palm Beach provide abundant food sources, including ornamental plants, flowers, and fruits. Iguanas have few natural predators in the state capable of controlling their numbers, allowing them to spread rapidly along the Atlantic and Gulf coasts.
The reproductive biology of the female iguana contributes to their population density, as they can lay clutches of up to 65 eggs in a single nesting season. While cold snaps (below 40 degrees Fahrenheit) can cause iguanas to become lethargic and temporarily fall from trees, these events do not significantly reduce the overall adult population. This combination of accidental introduction, favorable climate, resource abundance, and high reproductive output has cemented their status as a permanent part of the Florida ecosystem.
The Scope of Ecological and Structural Damage
The presence of iguanas results in two categories of negative impact: ecological disruption and structural degradation. Their herbivorous diet targets various native plants, including specific host species for threatened native insects. For example, they consume the nickerbean plant, which is the only host plant for the endangered Miami Blue butterfly larvae.
Iguanas compete with native wildlife for resources and sometimes directly prey on other species. They consume the eggs and young of native birds, which disrupts local breeding populations. They also use the burrows of native animals, such as the Florida burrowing owl and gopher tortoise, displacing these protected species from their habitats.
The reptiles’ burrowing habits represent a significant threat to man-made structures, leading to substantial economic costs. Iguanas dig extensive tunnels and nesting chambers near water bodies, which undermines seawalls, sidewalks, canal banks, and building foundations. This burrowing causes erosion, compromises the integrity of flood control systems, and can lead to the collapse of surfaces like patios and pool decks. Public health concerns also arise from their prolific defecation. Iguana droppings frequently contaminate swimming pools and public areas, carrying the risk of Salmonella transmission.
Regulatory Status and Management Strategies
Because iguanas are classified as an invasive species, they are not protected in Florida, except under general anti-cruelty laws. The Florida Fish and Wildlife Conservation Commission (FWC) encourages property owners to remove iguanas from their land to reduce the population’s negative effects. This legal status means residents do not need a permit to trap or remove iguanas on their private property, provided the action is carried out humanely.
The FWC prohibits the relocation of captured iguanas anywhere within the state. Any animal removed from a site must either be kept in captivity with a permit or humanely euthanized. Permissible removal methods for residents include live traps, noose poles, nets, and specific humane euthanasia techniques. The use of poisons or steel-jaw traps is illegal, and the FWC recommends that individuals unable to safely or effectively remove iguanas hire a professional nuisance wildlife trapper.
Property modification is a recommended strategy to deter iguanas from establishing residence. This involves removing favored food sources, such as certain flowering plants, and filling in potential burrowing sites along canal banks or under structures. Exclusion techniques, like installing fencing or barriers, can be employed to prevent access to gardens and nesting areas.