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SCIENCE DAILY (Rockville, Maryland) 04 December 13 Crocodiles Are Cleverer Than Previously Thought: Some Crocodiles Use Lures to Hunt Their Prey
Turns out the crocodile can be a shrewd hunter himself. A University of Tennessee, Knoxville, researcher has found that some crocodiles use lures to hunt their prey.
Vladimir Dinets, a research assistant professor in the Department of Psychology, is the first to observe two crocodilian species -- muggers and American alligators -- using twigs and sticks to lure birds, particularly during nest-building time.
The research is published in the current edition of Ethology, Ecology and Evolution. Dinets' research is the first report of tool use by any reptiles, and also the first known case of predators timing the use of lures to a seasonal behavior of the prey -- nest-building.
Dinets first observed the behavior in 2007 when he spotted crocodiles lying in shallow water along the edge of a pond in India with small sticks or twigs positioned across their snouts. The behavior potentially fooled nest-building birds wading in the water for sticks into thinking the sticks were floating on the water. The crocodiles remained still for hours and if a bird neared the stick, they would lunge.
To see if the stick-displaying was a form of clever predation, Dinets and his colleagues performed systematic observations of the reptiles for one year at four sites in Louisiana, including two rookery and two nonrookery sites. A rookery is a bird breeding ground. The researchers observed a significant increase in alligators displaying sticks on their snouts from March to May, the time birds were building nests. Specifically, the reptiles in rookeries had sticks on their snouts during and after the nest-building season. At non-rookery sites, the reptiles used lures during the nest-building season.
"This study changes the way crocodiles have historically been viewed," said Dinets. "They are typically seen as lethargic, stupid and boring but now they are known to exhibit flexible multimodal signaling, advanced parental care and highly coordinated group hunting tactics."
The observations could mean the behavior is more widespread within the reptilian group and could also shed light on how crocodiles' extinct relatives -- dinosaurs -- behaved.
"Our research provides a surprising insight into previously unrecognized complexity of extinct reptile behavior," said Dinets. "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."
Dinets collaborated with J.C and J.D. Brueggen from the St. Augustine Alligator Farm Zoological Park in St. Augustine, Fla. More of his crocodile research can be found in his book "Dragon Songs."
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CHINA POST (Taipei, Taiwan) 08 December 13 Crocodile and alligator species use logs to lure prey close enough to eat (Amina Khan, Los Angeles Times)
Los Angeles: As if crocodiles and alligators weren't terrifying enough, scientists have discovered that these ancient, sharp-toothed beasts are incredibly cunning. So clever that they use lures to trap and gobble unsuspecting birds.
The discovery in two crocodilian species — mugger crocodiles and American alligators — is the first report of tool use in reptiles, according to a study in the journal Ethology Ecology and Evolution.
Some birds, like egrets, actually choose to nest around crocodile and alligator hangouts because they offer some protection from tree-climbing predators like raccoons, snakes and monkeys. There's a blood price, however. Chicks and sometimes adult birds will become snacks for the crocodilians if they venture too close.
While on a research trip to Madras Crocodile Bank in Tamil Nadu, India, lead author Vladimir Dinets of the University of Tennessee noticed that mugger crocodiles seemed to be balancing twigs on their snouts.
“The crocodiles remained perfectly still for hours, and if they did move to change position, they did it in such a way that the sticks remained balanced on their snouts,” according to the paper.
Then, as an egret came close and leaned over to grab a stick, the crocodile suddenly lunged. The bird barely escaped with its life.
The study's two other co-authors noticed similar behavior over 13 years working at St. Augustine Alligator Farm Zoological Park in Florida.
Were the sticks purely there by coincidence? Was it just part of the camouflage? Or could these reptiles actually be using these sticks as lures?
After studying the habits of these reptiles at four sites in Louisiana for a year, the scientists confirmed that alligators and crocodiles do indeed use twigs to lure unsuspecting birds to their doom.
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