This week's issue of Science News has an interesting article about how certain species of birds sing in complicated and beautiful duets and choruses with such precision that it often sounds like a solo. In fact, researchers recently recorded wrens performing "the first four-part, synchronized chorus with alternative parts recorded outside human music." Make sure to listen to the sound samples. From the article:
Over several decades, scientists have offered at least a dozen explanations for the purpose of avian duets. The theories have focused on the forest, the pair, or conflicts of interest between individual birds.
The abundance of duetting in the tropics inspired some of the early explanations. Scientists in the 1970s noted that dense tropical vegetation would make sound especially important for mates identifying each other or keeping in contact. Recently, theorists have suggested that tropical birds duet to stay in sync reproductively, despite limited seasonal cues such as changes in day length.
Other scientists have stressed the partnership. For example, in the 1980s, the "coyness hypothesis" proposed that birds that consummated their pairing only after the arduous job of learning to duet would have a stronger bond that would discourage extra-pair adventuring.
Yet other theorists have suggested that duetting enables a bird to judge its mate's commitment to the partnership. Discouraging interlopers has been a popular theme, both in duetting to defend a territory and duetting to drive away a potential mate stealer…
The current generation of duetting studies often compares his-and-her agendas. One possible agenda is the male's clear interest in fathering the female's chicks. He may be chiming in to the female's song as a musical claim to paternity.
