Birds listen to, interpret, and pass on the alarm calls of other species when a predator approaches. Both birds and squirrels participate in this vast early-warning network, where calls announcing a predator travel at over 100 mph.
Remarkably, birds not only share the information that "a predator is coming," but they also convey information about the predator. Chickadees embed information about the size of predators into their alarm calls, with different acoustic indicators based on which predator looms. So an intriguing question remains: do other species pick up on these nuances? If so, birds would react differently based on how much of a threat a specific predator poses; for example, small, nimble pygmy owls are terrifying to chickadees, but less so to crows. Would a crow react more vigorously when they hear a "raptor" alarm cal versus a "pygmy owl" alarm call?
Stay tuned! And next time you wander into a forest, pay attention-- the forest network may well be announcing your presence.
Many thanks to Rachel Kolb for sharing this article!
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. Dr. Greene likened it to a bucket brigade at a fire. The information rippled ahead of a predator minutes before it flew overhead, giving prey time to hide. Moreover, while raptors can hear well at low frequencies, they are not very good at hearing at 6 to 10 kilohertz, he higher frequency at which seet calls are produced. "So it's sort of a private channel," he said.