DNA analysis confirms the presence of Nile crocodiles in Florida, which offers a perfect climate for the 18-foot long, human-devouring crocodiles from Africa to thrive.
Invasive species are awful things; when a new species is introduced to an established habitat, they can easily bully and overrun other species and negatively affect entire ecosystems. But it’s especially daunting when an invasive species happens to be an enormous crocodile with a taste for man-sized mammals.
Between the years 2000 and 2014, a handful of juvenile invasive crocodiles were found in Florida – swimming in the Everglades and one reclining on a private porch in Miami. Hello honey! And now University of Florida scientists have confirmed that these weren't just any ordinary crocodiles. As described in a new study, the researchers used DNA analysis and confirmed that the animals were Nile crocodiles (Crocodylus niloticus) linked to native populations in South Africa.In the last four years alone, Nile crocodiles were responsible for at least 480 attacks on people and 123 fatalities in Africa. I wasn’t kidding when I said they’re man-eaters. And in fact, they enjoy all kinds of prey – from zebras to small hippos to, as mentioned, humans in sub-Saharan Africa. In Florida, they have plenty to eat as well; from native birds, fish and mammals to the state's local crocs and gators.
And as it turns out, Florida seems to be a very nice place for the giant invaders, which, as National Geographic explains, can reach 20 feet in length and weigh up to 1,650 pounds. (Nat Geo also describes them as “primordial brutes.”) The study found one of the young Florida guys grew nearly 28 percent faster than wild Nile crocodile juveniles in their native range.
Kenneth Krysko, co-author of the study, says that there are probably more. "The odds that the few of us who study Florida reptiles have found all of the Nile crocs out there is probably unlikely," he says. "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."
While the DNA of the crocodiles were genetically identical – suggesting they were introduced by the same source – the exact place where they came from isn’t known yet. They don’t match the DNA of any live Nile crocodiles housed in U.S. zoos. It has been suggested that they were escapees from the pet trade.
The Nile crocodiles aren’t the first invasive species to find the Florida climate favorable; the Sunshine State probably has more invasive species than anywhere else on the planet. But the Nile crocodile may be the most dramatic.
"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."