Corps defends against invasive lizards

U.S. Army Corps of Engineers, Jacksonville District
Published March 31, 2020
Green Iguana

Green Iguana

Cold-stunned green iguanas, dubbed “chicken of the trees,” made national headlines as they fell from the trees in south Florida during a recent cold snap.

News stories and social media helped to raise public awareness about the damage that can be wrought by the large invasive lizards, which can reach more than five feet and twenty pounds. According to the media reports, these invaders weren’t just munching their way through the succulent plants of south Florida’s gardens, they also wreaked havoc on private properties and important public infrastructure, shorting out power lines and burrowing under structures, causing some of them to collapse. In one city, they reportedly contributed enough damage to a water control structure that the repair bill reached $1.8 million.

Construction, rehabilitation and maintenance of critical infrastructure are key missions for the U.S. Army Corps of Engineers, which is responsible for the 143-mile Herbert Hoover Dike around Lake Okeechobee, five navigation locks and dams and recreation areas along the 154-mile long Okeechobee Waterway, and Everglades restoration. Maintaining the integrity of these structures and protecting them from damage is integral to the success of these missions.

The U.S. Army Corps of Engineers, Jacksonville District has had experience managing invasive aquatic plant species since the late 1800s, when water hyacinth spread throughout the St. Johns River, blocking navigation. It was a turning point, when invasive species were recognized as a serious threat to navigation, agriculture, public health, flood control, and native plant and animal communities.

Since then, the Corps has developed strong partnerships, working on invasive species issues with local, state and federal agencies and other groups, including participation in the Everglades Cooperative Invasive Species Management Area (ECISMA).

Based on those relationships and partnerships, the Corps’ Invasive Species Management Branch has been able to monitor and anticipate the movement of animal species as they expanded their ranges in south Florida, and proactively put together a plan to maintain the integrity of much of the critical infrastructure within the Corps’ area of responsibility.

“The Corps has a really good relationship with the U.S. Department of Agriculture’s Wildlife Services and their missions align with ours. We were able to partner with them to provide invasive management services under the Economy Act. The main goal is to manage invasives that may compromise structural integrity and restore ecological stability,” said Corps biologist Jessica Spencer. “They are the main federal agency that has been responsible for controlling nuisance animal populations, with more than one hundred years of experience.”

“These large invasive lizards burrow and could damage Corps structures, so we’ve put a plan in place to address those potential issues and safeguard the integrity of our structures.” said Natural Resources Program Manager Nelson Colón. “The program to protect critical infrastructure has been very successful. Since the beginning of the program in 2018, more than 3,700 redhead agamas and more than 350 green iguanas have been removed from the Herbert Hoover Dike, the South Florida Operations Office in Clewiston and the surrounding area, the Port Mayaca Lock and Dam, the St. Lucie Lock and Dam, and the St. Lucie C-44 Canal.”

A similar program was implemented this year to monitor and remove invasive species that may affect Comprehensive Everglades Restoration Plan (CERP) Projects and the south Florida ecosystem.

Problematic invasive exotic species, both plant and animal, were originally introduced into the south Florida ecosystem by humans.

For Jon Lane, Chief of the Invasive Species Management Branch, and Corps biologist Joshua Bauer, the most important message for the public is this: Don’t release exotic plants or pets into natural ecosystems.

“Before you buy a pet, especially an exotic pet, please do your research and make sure you fully understand what you are getting into before making a purchase,” Bauer recommends. “These animals are beautiful and wonderful pets as long as owners have clear expectations and remain responsible. However, it is not always understood that a cute ten inch iguana could become a 5-foot long animal with breeding or food-related aggression, and carry diseases such as salmonella. Individuals just need to be aware of the responsibility and care required with these animals before purchasing them, as well as the challenges that can accompany the joy of owning exotic pets.”

“More importantly, if you find that you are unable to care for your pet appropriately, please don’t release it into the natural system. Exotics thrive in the south Florida ecosystem, which is often similar to their native habitat, without the natural predators or environmental pressures,” said Bauer. “In addition to damaging infrastructure, invasive plants and animals damage the south Florida ecosystem. Battling invasive species costs taxpayers millions of dollars every year.”

“Many people know that pythons are a huge problem, but so are other invasive reptiles, such as tegus, which are driven to nesting sites and eat the eggs of gopher tortoises, crocodilian species, and ground nesting birds,” says Bauer. “Tegus are an omnivorous large lizard species that will eat pretty much anything – even if they deplete the resource, they’ll continue eating whatever they find. If not managed, the predation and depletion of resources caused by these invasives could drive many native species into extinction.”

The Fish and Wildlife Conservation Commission’s Exotic Pet Amnesty Program helps to reduce the number of nonnative species being introduced into the wild by offering exotic pet owners who can no longer keep their pets a legal and responsible alternative to releasing their animals. People can surrender their exotic pets at the events, whether they are being kept legally or illegally, without penalty or cost. The Pet Amnesty Program does not euthanize animals, and finds a responsible home for them.

Exotic Pet Amnesty events are held around the state throughout the year. For additional information, visit or call the FWC’s Exotic Species Hotline at 888-Ive-Got1 (888-483-4681). Exotic pet owners who cannot attend the Pet Amnesty events may call this number year-round for assistance in finding a new home for their animal. People who are interested in adopting exotic pets may also visit and click on “Exotic Pet Amnesty Program” for more information.

Members of the public can also call the FWC’s Exotic Species Hotline at 888-Ive-Got1 (888-483-4681) to report invasive species sightings.

Learn more about the Corps’ Invasive Species Management programs at