Using DNA analysis, University of Florida researchers have confirmed the capture of multiple Nile crocodiles – human-eaters that can grow to 18 feet (5.5 m) long and weigh as much as a small car. Their study was published April 30, 2016 in the Journal of Herpetological Conservation and Biology.
The Nile crocodile, native to sub-Saharan Africa, eats everything from zebras to small hippos to humans. Now three juveniles of the monster crocodile have been found in South Florida – swimming in the Everglades and relaxing on a house porch in Miami.
The invasive crocodiles were captured between 2000 and 2014. Researchers analyzed their DNA, studied their diet and one of the animal’s growth. Scientists verified the animals were Nile crocodiles linked to native populations in South Africa, and confirmed the species can survive in Florida … and potentially thrive, said study co-author Kenneth Krysko, herpetology collections manager at the Florida Museum of Natural History.
In other words, there likely are more. Krysko said in a statement:
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 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.
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.
According to the study, Florida’s Atlantic coast and the entire Gulf of Mexico coastline provide favorable climate for Nile crocodiles. 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. Krysko said:
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.
Bottom line: A study published April 30, 2016 in the Journal of Herpetological Conservation and Biology confirms the capture of multiple Nile crocodiles – human-eaters that can grow to 18 feet (5.5 m) long and weigh as much as a small car – in southern Florida.
Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the award-winning EarthSky radio series almost since it began until it ended in 2013. Today, as Lead Editor at EarthSky.org, she helps present the science and nature stories and photos you enjoy. She also serves as one of the voices of EarthSky on social media platforms including Facebook, Twitter and G+. She and her husband live in Tennessee and have two grown sons.