Man-Eating Monster Nile Crocodiles Invade Florida

In other words, there likely are more.

“The odds that the few of us who study Florida reptiles have found all of the Nile crocs out there is probably unlikely,” said Krysko, co-author of the study published in April in the Journal of Herpetological Conservation and Biology. “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 are generalist predators and eat a wide variety of prey. In Florida, everything from native birds, fish and mammals to the state’s native crocodile and alligator would be fair game for the carnivorous croc.

The study found one juvenile grew nearly 28 percent faster than wild Nile crocodile juveniles from some parts of their native range.

DNA analysis revealed the three similar-size Nile crocodiles were genetically identical, suggesting they were introduced via the same source, but Krysko said the source has not been confirmed. Prior to graduating in 2013, former UF doctoral student and co-author Matthew Shirley extensively sampled DNA of live Nile crocodiles housed in U.S. zoos, including Florida. The DNA of the three crocodiles did not match any of those Shirley sampled, suggesting they were either acquired by a permitted source later, or introduced by someone without a permit.

Study scientists note that over the last decade, large groups of Nile crocodiles have been imported from South Africa and Madagascar for display at places like Disney’s Animal Kingdom and to supply Florida’s flourishing pet trade, with the latter being the most likely introduction pathway, according to the study.

Florida’s subtropical climate is one reason the state has the world’s largest number of invasive species — from the Burmese python that has invested the Everglades to the Cuban tree frog, which has been found as far north as Jacksonville on the East Coast and as far north as Cedar Key on the Gulf Coast.

“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,” Krysko said. “Now here’s another one, but this time it isn’t just a tiny house gecko from Africa.”

A large adult American alligator’s weight and length is 800 pounds (360 kg) and 13 feet (4.0 m) long, but can grow to 14.5 feet (4.4 m) long and weigh over 1,000 pounds (450 kg). The largest ever recorded was found in Louisiana and measured 19 feet 2 inches (5.84 m). The Chinese alligator is smaller, rarely exceeding 7 feet (2.1 m) in length. Alligators have an average of 75 teeth. Alligators are only native to the United States and China.

Contacts and sources:
Writer: Stephenie Livingston
Frank Mazzotti
Kenneth Krysko