A Review of Vocal Duetting in Birds

Avian duetting is an unusual but taxonomically widespread phenomenon, occurring in over 400 species, representing 40% of bird families. Duets vary in form from loosely overlapping songs to highly coordinated duets where paired birds both adjust the timing and type of phrases they sing to fit those of their partner over the course of the duet. Duet coordination therefore signals how attentive an individual is to its partner, both to the partner and to other listeners. While some aspects of duetting are poorly understood, such as its ontogeny and causation (including hormonal and neural bases), it is clear that duetting serves multiple functions, including maintaining the year-round territories and partnerships that characterize many duetting species. © 2009 Elsevier Inc. All rights reserved.