IN THE FIRST KNOWN case of an animal cracking the code contained in another species’ communication, a University of Washington biologist has found that red-breasted nuthatches understand, and respond to, subtle differences among alarm calls made by black-capped chickadees.
In previous work, doctoral student Christopher Templeton had observed that chickadees that spot predators vary the number of dees at the end of their chick-a-dee-dee-dee alarm based on the severity of threat. Small, agile raptors like pygmy owls, for example, elicit more dees than do larger, but less nimble, great horned owls. After seeing nuthatches react to such warnings, Templeton tested the birds’ ability to distinguish among them by playing chickadee calls on speakers at the base of trees containing nuthatch pairs. He found that more nuthatches responded more dramatically to pygmy owl alarms—flicking their wings in agitation and mobbing the speaker—than to great horned owl alarms.
“It turns out that these animals are pretty smart,” says Templeton, who published his results online in the Proceedings of the National Academy of Sciences. “Knowing what kinds of predators are around could be a matter of life or death, so it pays for them to listen to the alarm calls of other species.”—Laura Tangley