Nile Crocodiles Are Florida's Newest Invasive Species

Posted on May 22, 2016

Florida has added a new invasive species to its list. Researchers from the University of Florida say Nile crocodiles have been found in the wild in the state. The crocodiles can grow up to 18 feet long. They consume zebras, hippos and humans in their native home of sub-Saharan Africa.

Multiple Nile crocodiles have been captured in the wild in South Florida. They have been seen swimming in the Everglades and relaxing on a house porch in Miami. The captures were dated between 200 and 2014. The researchers say it is unlikely these were the only Nile crocs in the state.

Kenneth Krysko, herpetology collections manager at the Florida Museum of Natural History, says in the announcement, "The odds that the few of us who study Florida reptiles have found all of the Nile crocs out there is probably unlikely. We know that they can survive in the Florida wilderness for numerous years, we know that they grow quickly here and we know their behavior in their native range, and there is no reason to suggest that would change here in Florida."

Nile crocodiles, Crocodylus niloticus, were responsible for at least 480 attacks on people and 123 fatalities in Africa between 2010 and 2014. They eat a wide variety of prey and would be a threat to Florida's native birds, fish and mammals. The researchers found one juvenile grew nearly 28 percent faster in Florida than wild Nile crocodile juveniles from some parts of their native range.

DNA analysis of the Nile crocodiles found in Florida were genetically identical suggesting they were introduced via the same source. The source of the crocodiles is not yet known. The DNA was different to samples taken from live Nile crocodiles housed at U.S. zoos. The researches think the pet trade is the most likely source. Once introduced to southern Florida the region's subtropical climate allows the animals to thrive. The state is home to the world's largest number of invasive species.

Krysko also says, "My hope as a biologist is that the introduction of Nile crocodiles in Florida opens everyone's eyes to the problem of invasive species that we have here in our state. Now here's another one, but this time it isn’t just a tiny house gecko from Africa."

Krysko was the author of a study on Nile crocodiles in Southern Florida that was published here in the Journal of Herpetological Conservation and Biology in April 2016.

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