Green iguanas are an established invasive species in Florida. These large, primarily herbivorous lizards are native to Central and South America and some Caribbean islands. They first appeared in Florida in the Miami area during the 1960s; intentional releases from the pet trade led to their early establishment and continued spread.
Ecological Disruption
Green iguanas disrupt Florida’s ecology by consuming native plants and competing with local wildlife. As herbivores, they feed on shoots, leaves, blossoms, and fruits. Their diet includes ornamental plants popular in landscaping, as well as native vegetation.
The feeding habits of green iguanas threaten endangered native species. For example, they consume gray nickerbean, a host plant for the federally endangered Miami blue butterfly. Iguana foraging on this plant may have contributed to the disappearance of the Miami blue butterfly population in certain areas, such as Bahia Honda State Park.
Iguanas also compete with native wildlife for resources and habitat. They use the burrows of native species like the Florida burrowing owl and gopher tortoise, potentially displacing these state-threatened animals. Though primarily plant-eaters, iguanas also consume bird eggs and tree snails, affecting sensitive native populations.
Damage to Property and Infrastructure
Iguanas cause damage to structures and cultivated landscapes in Florida. Their burrowing habits are a major concern, as they dig tunnels that can undermine sidewalks, foundations, seawalls, and canal banks. This burrowing can compromise the structural integrity of these constructions, potentially leading to erosion and collapse.
Damage to seawalls is particularly prevalent, as iguanas often burrow along these structures, allowing water to seep underneath and accelerate erosion. In some instances, this has resulted in costly repairs to infrastructure, such as a dam in West Palm Beach that required $1.8 million in emergency repairs partly due to iguana burrowing.
Beyond structural damage, iguanas destroy ornamental plants, gardens, and agricultural crops. They consume various fruits and vegetables, causing losses for homeowners and businesses. Iguanas can also infiltrate electrical facilities, climbing onto transformers or into breaker boxes, which can lead to power outages.
Public Health and Safety Concerns
Green iguanas can pose public health and safety concerns due to their ability to transmit bacteria. Iguanas carry Salmonella bacteria in their intestinal tracts. They can shed this bacteria through their feces, which then contaminates surfaces, water bodies, and even swimming pools.
Contact with contaminated surfaces or water, or direct handling of iguanas without proper hygiene, can lead to Salmonella infection in humans. Symptoms include diarrhea, fever, and abdominal cramps, though severe cases can occur, particularly in young children, the elderly, or immunocompromised individuals.
While generally not aggressive, iguanas can bite or scratch if they feel threatened or cornered. Therefore, caution is needed when encountering these large reptiles.
Factors Driving Their Spread
Several factors contribute to the rapid proliferation and spread of green iguanas in Florida. The state’s warm, subtropical climate provides an ideal environment for their survival and reproduction, closely mimicking their native habitats.
Florida’s extensive network of canals and waterways also aids their dispersal, allowing them to colonize new areas. Their ability to adapt to various habitats, including urban and suburban environments, supports their expansion.
Green iguanas breed rapidly, with females laying clutches of 10 to 70 eggs in burrows they dig. They can reach sexual maturity as early as two to four years of age, and their eggs incubate for approximately two to three months. Adult iguanas have few natural predators in Florida, allowing their populations to grow unchecked. While some native animals prey on eggs and young iguanas, large adults face few threats other than alligators and humans.