Saturday, May 30, 2015
Dr. Greene says he wants to better understand the nuances of these bird alarms. His hunch is that birds are saying much more than we ever suspected, and that species have evolved to decode and understand the signals. Dr. Greene turned to chickadees, which are highly attuned to threats.
A 2005 study published in the journal Science demonstrated how black-capped chickadees embed information about the size of predators into these calls. When faced with a high-threat raptor perched nearby, the birds not only call more frequently, they also attach more dee’s to their call.
Studying the phenomenon, he documented a “distant early-warning system” among the birds in which the alarm calls were picked up by other birds and passed through the forest at more than 100 miles per hour. While admittedly the study is fascinating, what benefit does this information provide?
Birds must make a trade-off with their time between eating and being vigilant. Alarm calls help the group share that responsibility. But when birds cannot hear predators or alarms well, each must spend more time listening and less time feeding. Noise alone (traffic and other human disturbances), has harmful effects on many of the birds.
Most migratory birds worldwide are in decline today, and noise pollution hampers their ability to hear information such as warnings and forces them to change their behavior. This work could have important implications for conservation.
Original Article: When Birds Squawk, Other Species Seem to Listen
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