In the 1950s, the US pet trade began importing caimans; decades later, they may be competing with native crocodilians in the Everglades wetlands

Pet stores imported baby caimans from the 1950s. Now they live in Florida, and a 10-year effort removed 251, while scientists weigh the risk to native wildlife.

There’s a small reptile that looks like a baby alligator somewhere in the Florida Everglades, living far from its home in Central and South America. That’s the story of the spectacled caiman. According to a U.S. Army Corps of Engineers news release, caimans have been established in Florida since the 1970s and were spotted there as early as the 1950s. The release includes a study from the University of Florida about how scientists got them out of parts of the Everglades.

The spectacled caiman, a small crocodilian, now lives in parts of the Florida Everglades. (Wikimedia Commons)

How baby alligator replacements ended up in the wild

A U.S. Fish and Wildlife Service risk screening summary helps explain how it all began. When trade in baby American alligators became illegal, the pet industry resorted to importing thousands of baby caimans instead. It began in the 1950s and continued into the early 1980s. Many were later released or escaped, and the summary states that most records of nonnative caimans in the U.S. can be traced to such releases. A breeding population was discovered at a Florida Air Force base in 1974. More caimans were released in Dade County in August 1992 when Hurricane Andrew destroyed cages at an exotic animal dealer.

Why scientists are worried

The Army Corps release says caimans share habitat with native alligators and crocodiles and may compete for food and other resources. They also feed on birds, small mammals, fish, and other reptiles. The Fish and Wildlife Service summary is more cautious in its assessment. It describes the total risk involved as uncertain and claims that there needs to be more peer-reviewed research in the field. Despite that, scientists working at state and federal agencies believe that the invasion has also impacted the restoration goals of the Comprehensive Everglades Restoration Plan (CERP). The release points out that CERP costs over $24.5 billion and is the largest ecosystem restoration project in the United States.

The American crocodile (Crocodylus acutus), a native species that shares Florida’s wetlands with the invasive caiman. (Wikimedia Commons)

Ten years of searching and removing

Sidney Godfrey, a wildlife biologist and lead author of the study, was part of a team from the University of Florida’s Institute of Food and Agricultural Sciences that compiled data from 2012 to 2021. Their study was published in Management of Biological Invasions in 2023. In December 2012, the team began surveying and removing caimans in the Biscayne Bay Coastal Wetlands. In 2017, it expanded its efforts with increased state and federal support. In 2018, it expanded to the C-111 Canal Project to get an early start on a second, more recently discovered population of caiman.

Members took weekly surveys, responded quickly to reported sightings, and studied captured caimans through necropsies, which are animal autopsies. Over 10 years, they removed 251 caimans from 11 search routes. Annual removals increased from five in 2012 to 47 in 2020. Necropsies told them when caimans nested and hatched, allowing them to target breeding adults and hatchlings.

What the results do and do not show

Godfrey said the team is cautiously optimistic that its work may be affecting the overall caiman population in the restoration areas. That statement is only true in the specific areas studied. He added that the relatively quick reduction, more than 60 years after the introduction of caimans, gives hope that continued efforts may be successful. Frank Mazzotti, a University of Florida wildlife ecology professor, said managing invasive wildlife is not an in-and-out process. He said long-term removal, inter-agency cooperation and continued monitoring would be key.

The only other peer-reviewed removal study in South Florida was done over 40 years ago and was about one year long and in a relatively small area. Godfrey said earlier attempts failed, but they may have ended too early. When the study was published in 2023, the team said its next steps included developing new tools, such as thermal imaging cameras, to find caiman nests. It also planned to publish dietary and genetic information about the caimans to raise public awareness of their impact on native wildlife and their origins.