Killer Nile crocodiles in Florida? Experts say it's possible

Krysko and his co-authors just published a paper showing that DNA testing proved the three animals captured in 2009, 2011 and 2014 are Nile crocs, a species whose males grow to over 16 feet long and weigh upward of 1,600 pounds.

Krysko, who works at UF's Florida Museum of Natural History, said the captured crocodiles matched genetically, meaning they are related to one another, but didn't match Nile crocs kept at Disney's Animal Kingdom and other licensed Florida attractions.

The Nile croc, if it became established in the Everglades, would pose another invasive threat to its teetering ecosystem.

Through crossbreeding, they could endanger the smaller, less aggressive American crocodiles, which have never been responsible for a confirmed human death in the U.S. About 1,000 American crocodiles live in South Florida, mostly in mangroves and estuaries.

Nile crocs also are known to attack livestock, which would be bad news for cattle farms that border the Everglades.

Krysko and two co-authors, independent wildlife biologist Joe Wasilewski and UF wildlife ecology professor Frank Mazzotti, think more Nile crocs lurk unfound in the Everglades, but they aren't certain.

Allyson Gantt, a spokeswoman for Everglades National Park, where one of the reptiles was found, disagrees, saying no Nile crocs still roam the park.

Some Everglades visitors might not be aware of the differences between crocodiles and alligators, complicating efforts to confirm any remaining crocs.