This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Do alligators use tools? This isn’t a trick question. A 2013 paper by Vladimir Dinets and colleagues suggested that alligators living near bird rookeries intentionally balanced sticks on their snouts to lure nesting birds into chomping range. One alligator seemed to be successful, in fact, apparently making the most of its dinosaurian cousin's curiosity.
The observation was taken as an example of tool use among alligators, a first for their reptilian ilk. I went a little bit further in a blog post – if both birds and crocodylians can use tools, could non-avian dinosaurs have fashioned or utilized tools, too? But now a new study by biologists Adam Rosenblatt and Alyssa Johnson has thrown cold water on the idea of such ecothermic innovation. Alligators are certainly smart, but it doesn’t seem like they’re intentionally luring in their avian acquaintances.
Even though the idea of extra-clever alligators is fascinating, Rosenblatt and Johnson point out that the original paper was more of a speculative report than a real analysis. “The observations by [Dinets and coauthors] are anecdotal, the systematic observations are correlative, and the behavior has never been documented leading to successful predation of birds in the wild,” is the more technical way of putting it. But rather than writing off the idea entirely, Rosenblatt and Johnson tested it.
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The biologists turned to captive reptiles at the St. Augustine Alligator Farm, Gatorland, Gatorama, and Everglades Alligator Farm to investigate the possibility. Aside from their locations, a critical difference marks the attractions. While the St. Augustine Alligator Farm and Gatorland seasonally host bird rookeries around the alligator ponds, Gatorama and Everglades Alligator Farm don’t. This means that Rosenblatt and Johnson could assess whether alligators living near bird nest sites would show stick-displaying behavior more often – as would be expected – or if the alligators at the other parks would do the same without birds nearby. The researchers even added some branches to the ponds to ensure that all the alligators would have a chance to play Pick Up Sticks if they wanted to, with the biologists recording how long the alligators balanced the twigs on their snouts and if any birds approached.
The sticks seemed to be a hit with the alligators. Rosenblatt and Johnson documented “stick displaying behavior” by alligators at all four sites, but not in a way that supported the tool-use idea. In fact, alligators at one of the sites without nesting birds "displayed" with sticks more often than those with potential lunches to lure. Only four alligators engaged in the behavior for more than ten minutes, all of which at sites with birds, but no birds approached the alligators and no alligators tried to nab the birds. This is despite the fact that the researchers timed their observations for when the egrets and other birds would be building their nests, the avians collecting sticks from other places around their enclosures.
No one knows why alligators balance sticks on their noses sometimes. As it stands, Rosenblatt and Johnson point out, the sticks can easily be transported onto the snouts of penned alligators and most balance the sticks for a minute or less. The behavior may not be intentional at all, it could be crocodylian curiosity, or something else entirely. And while this doesn’t mean alligators are incapable of using tools – or even inventing a behavior like balancing sticks as lures – there’s no solid evidence for tool-using gators yet. At least, not outside comic books.