An invasive crocodile that can grow to 18 feet and weigh as much as a small car has been discovered in Florida.
Using DNA analysis, researchers confirmed the capture of multiple Nile crocodiles in the wild. The ancient icon eats everything from zebras to small hippos and even humans in sub-Saharan Africa. Now three juveniles of the monster crocodile species have been found in South Florida, swimming in the Everglades, and relaxing on a house porch in Miami.
The crocodiles were captured between 2000 and 2014, leading scientists to analyze their DNA, and study their diet and one of the animal’s growth. Their research verified that the animals were Nile crocodiles linked to native populations in South Africa, and confirmed the species can survive in Florida—and potentially thrive.
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,” says Kenneth Krysko, herpetology collections manager at the Florida Museum of Natural History at the University of Florida.
“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.”
“The odds that the few of us who study Florida reptiles have found all of the Nile crocs out there is probably unlikely.”
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, published in the Journal of Herpetological Conservation and Biology, reported one juvenile that 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 the source has not been confirmed. Researchers extensively sampled DNA of live Nile crocodiles housed in US zoos, including Florida. The DNA of the three crocodiles did not match any of those 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.
While there is currently no evidence of an established population, scientists recommend a scientific risk assessment to evaluate the potential for Nile crocodiles to breed and spread across the state. 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—including the Burmese python that has invested the Everglades and 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 says. “Now here’s another one, but this time it isn’t just a tiny house gecko from Africa.”
Source: University of Florida