Wed February 4, 2009
Earth Notes - Chickadee Alarms
Flagstaff, AZ – Earth Notes: Chickadee Alarms
During the chilly days and nights of winter, the small songbirds of western mountains flock together for companionship and for the security of many active eyes working together to spot food and predators.
Among forests and woodlands, mixed groups of softly chattering chickadees, titmice, nuthatches and other birds weave their way through the branches. Watch for a while, and you may get a sense of how flock members cooperate and move together as a group.
If a predator appears, the birds suddenly get very excited. Their voices escalate several notches into harsh scolding that's surprisingly sophisticated. New research by Christopher Templeton at the University of Washington has shown just how complex it is.
Chickadees, it turns out, often sound an alarm through a complex code of calls. Templeton and other biologists have learned that the number of "dee" notes in the familiar "chick-a-dee" call refers to different types of predators.
For instance, two "dee" notes signal the presence of a large but relatively unthreatening predator, like a great horned owl. Four "dee" notes mean a greatly feared predator is present, like a pygmy owl or sharp-shinned hawk.
Yet the most remarkable thing that biologists have learned about these calls is that unrelated red-breasted nuthatches can understand them and respond accordingly. That was a surprise.
But maybe it shouldn't be: after all, these birds have been flocking for a long time, and mutual understanding is a big step in learning to live together more effectively.