Florida’s native crocodiles and alligators could be at risk from the spectacled caimans which now call the place their home. For as long as the non-native caimans lives there, it presents an existential threat to the integrity and restoration of the entire Everglades ecosystem.
More than 60 species of non-native reptiles and amphibians live in the state of Florida. The spectacled caiman, which has a spectacle-like ridge between its eyes and can grow up to 2.5m long, is one of them.
The species, which is native to Central and South America, was introduced to the United States over 60 years ago via the pet trade. When owners of the exotic species could no longer care for them, they released the reptiles into the Everglades, where they bred and became established.
Writing in Frontiers in Amphibian and Reptile Science, Sergio Balaguera-Reina and colleagues from the University of Florida Institute of Food and Agricultural Services describe why the species is so problematic.
“Spectacled caimans have the potential to impact South Florida’s ecosystems by competing with native crocodilians as well as other predators,” they say.
Caimans are opportunistic carnivores. They will eat just about any animal they can, including insects, fish, reptiles, birds and mammals. By consuming prey that native crocodilians could eat, they make the reptiles’ lives more difficult.
They don’t distinguish between native and non-native, or rare and common prey species. Now, as they take chunks out of the local food web, they risk causing it to collapse.
They’re also not fussy where they live. As part of the Everglades Restoration Plan, which began over 20 years ago, new ponds, canals and marshes were created. These are now providing homes, not just for native wildlife, but for spectacled caimans too.
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At present, two genetically distinct populations of caimans exist. One, which is more localised, hails from northern Brazil–southern Guyana. The other, which is more broadly distributed, originates from Columbia. For now, it’s thought the two populations have not overlapped or interbred, but if they do, it could boost the species’ genetic diversity and increase its resilience.
“Admixture (interbreeding) is expected if these populations are not managed and let to grow,” the authors say.
Since 2017, more than 340 spectacled caimans have been removed from Florida as part of an active programme to manage them. Now the researchers are calling for more research and monitoring. “All this highlights the need for more thorough efforts to remove, control and monitor invasive populations,” they say.
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