A researcher working for the University of Tennessee, Knoxville, has recently established that crocodiles and alligators have the incredible forethought to exploit their environment, whilst hunting down unsuspecting prey.
Research Assistant Professor Vladimir Dinets, who is based in the university’s Department of Psychology, was the very first scientist to witness two distinct species of the deadly aquatic tetrapod using stick-displaying predation techniques to tempt birds into venturing closer to their deadly jaws.
The Stick-Displaying Rouse
The research was published in the latest issue of the journal Ethology, Ecology and Evolution. Dinets’ study was the very first to fully illustrate the novel hunting techniques employed by muggers and American alligators, who would often organize their cunning trickery to coincide with the nest-building season of birds.
The American alligator (Alligator mississippiensis) is a large crocodilian reptile, extant to the southeastern United States, with a population that largely inhabits coastal areas, brackish lakes and cays. The average male American alligator often reaches a length of between 3.5 to 4.5 meters and weighs around 450 kilograms. In terms of coloration, the American alligator has a relatively bland, grey/brown to black hue, with a cream-colored underside.
On the other hand, mugger crocodiles (Crocodylus palustris) are generally found throughout the Indian subcontinent, Pakistan and Sri Lanka. Muggers are between four to five meters long and display the broadest snout of any living member of the Crocodylus genus. They are medium-sized crocodiles that occupy freshwater lakes, ponds, rivers and swamps. Adults are heavily armored and have a brown/dark grey color.
Both species of croc direct attacks towards larger mammals and typically focus on hunting birds, fish and reptiles. Whereas the American alligators rarely targets larger mammals, the mugger croc is known to ambush small to medium-sized mammals and can pose a serious threat to humans.
Dinets states that he first stumbled across the unorthodox behavior, back in 2007, when he identified a number of crocodiles mulling around in the shallow waters of a pond in India. These tenacious creatures would float at the edge of the waters, balancing twigs on their snouts, and patiently awaiting the arrival of unwary nest-building birds, between the months of March and May.
Sometimes, hours could pass without hide nor hair of the dim-witted birds. Eventually, however, once a bird waded close enough to the nestled pile of sticks, the crafty croc would violently lunge towards its victim.
The Rookery Study
Dinets and colleagues elected to conduct more rigorous investigation into this creative form of predation, and monitored alligators at four separate sites in Louisiana, over a period of a single year. The team selected a total of four observation sites, including two rookeries and two non-rookeries. Rookeries are regions that represent prime breeding grounds for crows, rooks and colony-forming seabirds.
Ultimately, over the course of the year, most of the reptiles were found to display sticks during the nest-building season. Intriguingly, however, those alligators that were spotted around the rookeries used the stick-presenting predation tactic both during and after the nest-building season. Meanwhile, at non-rookery sites, they typically only used the technique during a period when birds were scouring the area for sticks.
Dinets ruminates over his team’s research findings, explaining that, whereas crocodiles and alligators were once considered “lethargic, stupid and boring,” they are now known to demonstrate advanced communication practices and parental care, alongside group hunting strategies:
“Our research provides a surprising insight into previously unrecognized complexity of extinct reptile behavior… These discoveries are interesting not just because they show how easy it is to underestimate the intelligence of even relatively familiar animals, but also because crocodilians are a sister taxon of dinosaurs and flying reptiles.”
By James Fenner