for National Geographic News
Black-capped chickadees employ some surprisingly sophisticated warning calls to alert birds of the same feather to the danger of predators, new research reveals.
For human soldiers, the words "enemy tank!" may cause an entire troop to take aim, whereas "enemy sniper!" may rally only a few soldiers for the capture.
Likewise, chickadees relay similar details about the threats posed by predators and the response required. The songbirds' encode the information in their namesake "chick-a-dee" call.
The greater the threat, the larger and more aggressive the feathered mob that forms to harass the predator away.
"It's like they're saying, Hey, there's a perched or terrestrial predator over here, come harass it," said Christopher Templeton, a biology doctoral student at the University of Washington in Seattle. "Subtle variations of the call elicit the level of threat the predator poses."
Templeton and his colleagues say their findings, described in tomorrow's issue of Science, demonstrate an unexpected level of complexity and sophistication in songbird communication.
Susan Smith, a leading authority on black-capped chickadees who was not involved in the study, said she wasn't surprised by the discovery.
In an e-mail to National Geographic News, the Mount Holyoke College biologist said the finding "demonstrates a level of sophistication that I suspect is very common among bird vocalizations."
Black-capped chickadees are common backyard visitors throughout North America. During winter months, the 5-inch-tall (13-centimeter-tall) birds form flocks of about six to eight individuals and collectively stake out and guard woodland territories.
At the sight of a predator, and depending on its location, the songbirds make one of two types of warning call.
Chickadees voice a soft, high-pitched "seet" to warn of airborne predators, such as owls and hawks. The alert tells other chickadees to take cover and freeze in place until "somebody gives the all-clear call," Templeton said.
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