Convergence of calls as animals form social bonds

Abstract

In many species capable of vocal production learning, the acoustic properties of calls from different individuals can converge when they are housed together in captivity or form social bonds in the wild. This has been demonstrated for animals as diverse as songbirds, parakeets, bats, cetaceans, and primates. In many species of songbirds, territorial neighbors have repertoires with several shared songs. Males can use the shared songs during territorial disputes, and birds escalate or de-escalate a countersigning interaction by choosing to reply with a song match, a repertoire match, or an unshared song. For most other species, call convergence is thought to reflect a group-distinctive identifier, with shared calls reflecting and strengthening social bonds. I will discuss examples of call convergence in primates, birds, elephants, and cetaceans. The breadth of the use of production learning for call convergence suggests that this may have been an important selective pressure for the evolution of production learning. Some species have well-developed capabilities of imitating distinctive calls of other individuals or groups. This capability of learning to imitate an arbitrary signal for an arbitrary referent may have evolved out of simpler forms of vocal convergence.