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First documented tool use by reptiles claimed

Dec. 11, 2013
Courtesy of Taylor & Francis journals
and World Science staff

How do croc­o­diles catch their flighty friends? 

Though we might ex­pect birds to easily evade their cap­tors, croc­o­diles have been ex­posed as the mas­ter­minds of a new hunt­ing meth­od, sci­en­tists re­port.

A camouflaged mug­ger cro­co­dile in stick-dis­play­ing be­hav­ior. (Cour­tesy Tay­lor & Fran­cis)


Ly­ing still in the wa­ter and bal­anc­ing sticks and twigs on their snouts or in their mouths, the croc­o­diles ap­pear more cun­ning than a fox, the re­search­ers say. At nest­ing time, birds fly down to col­lect fo­li­age for their new homes but are met with an al­to­geth­er dif­fer­ent home com­ing—to the great bird’s nest in the sky, as they are eat­en.

Though the use of ob­jects as hunt­ing lures is very rare in na­ture, a study says at least two spe­cies of croc­o­diles and al­li­ga­tors use twigs and sticks to lure birds. One spe­cies is the mug­ger croc­o­dile Croc­ody­lus palus­tris, the oth­er is the Amer­i­can al­li­ga­tor Al­li­ga­tor mis­sis­sip­pi­ensis.

The re­search is pub­lished in the cur­rent is­sue of the jour­nal Ethol­o­gy, Ecol­o­gy and Ev­o­lu­tion and is the first re­port of tool use by any rep­tiles, the re­search­ers say.

“This is the first known case of a pred­a­tor not just us­ing ob­jects as lures, but al­so tak­ing in­to ac­count the sea­son­al­ity of prey be­hav­ior,” wrote the in­ves­ti­ga­tors, Vlad­i­mir Di­nets of the Uni­vers­ity of Ten­nes­see and col­leagues.

“Dur­ing the nest-building sea­son, many wad­ing birds are des­per­ately search­ing for small sticks and twigs, of­ten en­gag­ing in steal­ing from their neigh­bors and vi­o­lent fights,” they not­ed. The rep­tiles ex­ploit this.

The study was based on year­long ob­serva­t­ions at four sites in Lou­i­si­ana. In­ves­ti­ga­tors ob­served each site be­tween one and four hours af­ter sun­rise, monthly in August-February and weekly in March-July, cov­er­ing the nest-building sea­son of March 24-May 5.

“The spec­tac­u­lar com­plex­ity of croc­o­dil­ian be­hav­ior has been rec­og­nized only re­cent­ly,” the re­search­ers wrote. “His­toric­ally viewed as le­thar­gic, stu­pid and bor­ing,” they went on, croc­o­diles and alli­gators are now known to show flex­i­ble com­mu­nica­t­ion, “ad­vanced pa­ren­tal care and highly co­or­di­nated group hunt­ing tac­tics.”

The find­ings sug­gest that di­no­saurs, close rel­a­tives of croc­o­diles and al­li­ga­tors, may al­so have ex­hib­ited com­plex be­hav­ior, they added.


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How do crocodiles catch their flighty friends? Though we might expect birds to easily evade their captors, crocodiles have been exposed as the masterminds of a new hunting method, scientists report. Lying still in the water and balancing sticks and twigs on their snouts or in their mouths, the crocodiles appear more cunning than a fox, the researchers say. At nesting time, birds fly down to collect foliage for their new homes but are met with an altogether different home coming—to the great bird’s nest in the sky, as they are eaten. Though the use of objects as hunting lures is very rare in nature, a study said at least two species of crocodiles and alligators use twigs and sticks to lure birds. One species is the mugger crocodile Crocodylus palustris, the other is the American alligator Alligator mississippiensis. The research is published in the current issue of the journal Ethology, Ecology and Evolution and is the first report of tool use by any reptiles, the researchers say. “This is the first known case of a predator not just using objects as lures, but also taking into account the seasonality of prey behavior,” wrote the investigators, Vladimir Dinets of the University of Tennessee and colleagues. “During the nest-building season, many wading birds are desperately searching for small sticks and twigs, often engaging in stealing from their neighbors and violent fights,” they noted. The reptiles exploit this. The study was based on yearlong observations at four sites in Louisiana. Investigators observed each site between one and four hours after sunrise, monthly in August-February and weekly in March-July, covering the nest-building season of March 24-May 5. “The spectacular complexity of crocodilian behavior has been recognized only recently,” the researchers wrote. “Historically viewed as lethargic, stupid and boring, crocodilians are now known to exhibit flexible [communication], advanced parental care and highly coordinated group hunting tactics.” The findings suggest that dinosaurs, close relatives of crocodiles and alligators, may also have exhibited complex behavior, they added.