The American alligator has long been known as a fierce apex predator, easily capable of taking down its typical freshwater prey — fish, crustaceans, wading birds — and very occasionally going after humans.
James Nifong, the lead author of the study, spent nearly a decade observing American alligator populations along the coasts of Florida and Georgia. More often than not, his research involved headlamps and nocturnal boat rides through alligator-filled waters, since the animals usually hunt at night.
Over that period, Nifong and the teams he worked with temporarily caught more than 500 alligators and pumped their stomachs using a hose, a pipe and something of a Heimlich maneuver. (He also became quite adept at alligator wrangling: “Anything less than four feet long we just hand-grab and bring it on the boat,” Nifong told The Washington Post.)
From there, researchers painstakingly filtered through the contents of the alligators' stomachs to try to identify what the animals had eaten.
“It is meticulous, going through it, sorting through it,” Nifong said. “A lot of these things we're identifying, they're very small or we really only have small fragments of things.”
Researchers documented evidence that the alligators had consumed three new species of sharks and one new species of stingray, Nifong said. He estimated that the largest sharks eaten were three to four feet long, while the largest stingrays consumed were probably two to three feet long.
Nothing on the level of “Jaws,” sure — but Nifong noted it was possible that there were larger, untrapped gators out there that had taken down bigger sharks as prey.
“There's not a ton of people out there stomach-pumping very large alligators,” he said. “They're actually very difficult to stomach-pump and retrieve prey items. It's very tough to be certain that you got everything out of there.”
For several years, researchers also affixed GPS tracking devices to the alligators they caught and released to observe their travel patterns.
What they found was that the gators were “opportunistic predators” who could leave their freshwater habitats — usually small ponds on barrier islands or areas right behind coastal dunes — and swim down estuaries through increasingly salty water, toward the coast, Nifong said.
Despite a lack of salt glands, some alligators were able to stay in a marine environment for days at a time, “then go back to fresh water, rehydrate and go back out,” Nifong said. One animal they tracked with GPS stayed in a saltwater environment for 32 consecutive days. Nifong suspects that heavy rainfall at the time helped the alligator survive.
“In the happenstance that it rains out there, they can actually drink the fresh water off the top of the salt water,” he said.
Nifong said more research is needed to determine whether alligators were consuming sharks in greater numbers and why. He found historical reports of clashes between sharks and alligators back in the late 1800s, but he said their interactions may have increased in recent years as a result of development.
“Both populations have suffered declines, and you've got a lot of coastal development that have decreased their access to estuarine habitats,” he said. “Historically, alligators were considered just a freshwater species. We found that not only do they habitually use marine habitats, there are very important linkages between those two systems . . . We need to account for those interactions when we're planning for those conservation efforts.”
That research may have to wait. Nifong, a Florida native, is on a year-long appointment as a postdoctoral researcher with the Kansas Cooperative Fish and Wildlife Research Unit at Kansas State University.
“I'm studying native fish in Kansas streams, looking at what's affecting their populations,” Nifong said, laughing. “It has nothing to do with alligators.”