I remember when zoo officials in Tulsa were wondering why the ducks keep disappearing. Then they found a gator that had escaped the gator pond and had lived off the ducks for several years. And it get Very Cold in Tulsa at times.
Also reminds me of when a shark was found in the Elephant Butte res in New Mexico about 45 years ago!
Piranha have been found in the Everglades. Then there are the Snakeheads in the Louisiana swamps. OH WAIT! That was James Carville!
Gotta keep a close eye on the gators! They adapt a little bit! ;)