Black-capped chickadees like this research subject have a sophisticated alarm system for warning their flock mates of danger, scientists say.
When they spot a predator, black-capped chickadees vary their alarm cries. The warnings help flock mates grasp the relative threat posed by the predator, researchers report in this week's issue of the journal Science.
Chickadees use their calls to organize a defense, mobbing predators to drive them away. The tiny birds' call can vary in several ways when predators are near, says Chris Templeton, a biology doctoral student at the University of Washington and the study's lead author.
Flying raptors, such as owls, hawks and falcons, provoke a soft, high-pitched "seet" call. The louder, signature "chick-a-dee" call signals a stationary or perched predator nearby. Smaller raptors like the small pygmy-owl and the American kestrel — which are more maneuverable in flight, and thus better at hunting small birds — provoke more "dees" at the end of a call, resulting in more chickadees mobbing together to defend themselves.