The function of alarm calls and their variation in Eurasian magpies

Summary

While complex languages are unique to humans, also animals vocalise to communicate. But why and what do animals communicate? I explored in which contexts Eurasian magpies emitted their characteristic, harsh and loud “chatter” alarm call. I found that chatters are produced when facing predators or other magpies intruding their territory. The call duration and pitch, however, greatly vary within and across contexts. The presence of other magpies also makes a difference in how they respond and call to predators. It seems that long chatters are used by pairs and families to repel foxes or other magpies from the territory, whereas shorter calls may be emitted to warn other magpies of dangerous predators. In addition, playing back different chatter call variants elicited different responses of magpies. Hence, a single alarm call type may have different functions and meanings depending on how and in which context it is emitted, expressing a great complexity of a seemingly simple call.