If Dr. John Watson had been chronicling the work of Christopher Templeton rather than the exploits of Sherlock Holmes, he might have entitled the latest research by Templeton "The Adventure of the Avian Eavesdroppers."
The University of Washington doctoral student has found the first example of an animal making sophisticated decisions about the danger posed by a predator from the information contained in the alarm calls of another species.
In a paper published this week in the on-line edition of the Proceedings of the National Academy of Sciences, Templeton reports that red-breasted nuthatches (Sitta Canadensis) eavesdrop on the alarm calls of the black-capped chickadee to glean information about predators in their environment. Two years ago, Templeton showed that the chickadees (Poecile atricapillus) familiar chick-a-dee-dee-dee alarm calls contained a surprising amount of information. Now, it turns out, the nuthatches can understand the warnings given by the chickadee.
"No one has ever seen this behavior before. There are a fair number of animals that respond to other animals alarm calls. But this is the first example of subtle information from a call being interpreted by another species," said Templeton. "Nuthatches can tell if a raptor poses a high or low danger from the chickadees alarm call."
His earlier work showed that the chickadees had two types of alarm calls to warn about predators. When they see flying raptors birds of prey such as hawks, owls and falcons they issue a soft, high-pitched "seet" call. However, when they see a stationary or perched predator, chickadees use a loud, wide-spectrum chick-a-dee-dee-dee alarm to recruit other birds to harass, or mob, the predator and chase it away.
Analysis of recorded chickadee mobbing calls indicated that the acoustic features of the calls varied with the size of the predator observed. Most typically chickadees change the dee-dee-dee note at the end of the calls
Contact: Joel Schwarz
University of Washington