Songbird Duets

Are you and your significant other perfectly synchronized to sing in sweet, sweet harmony?  A paper published recently by Eric Fortune and colleagues in the journal Science has shown that couples of one species of songbird called the plain-tailed wren (Pheugopedius euophrys) do just that.  Plain-tailed wrens live in bamboo thickets in the Andes in South America.  In most species of songbirds only the male birds sing and they perform their song to attract females and defend their territory.  What is unique about the plain tailed wrens is that both males and females sing in a duet.  They alternate singing parts (or syllables) of the song so that it sounds like the whole song was produced by only one bird.  This takes remarkable coordination between the male and female birds.  Males and females each produced the same syllables whether singing together or alone but when both partners sang together they adjusted the amount of time between syllables to coordinate with their partner indicating that they were listening to both their own voice and their partner's during singing.  It appears that the females may be largely responsible for keeping the song on track.  Male songs were more variable and sometimes males would stop singing prematurely but the female would continue the song allowing the male to rejoin her.  The researchers recorded the activity of neurons in region of the brain that drives the motor output of the song called HVC.  In most birds this region of the brain will respond to auditory playback only of the song it actually produces.  In duetting wrens, however, the neurons responded best to playback of the duet song in its entirety even though each wren only produces half of the song.  The exact function of the duet is unknown, though it is thought to play a role in territory defense.  Could it be that the females are choosing males based on their ability to listen to and synchronize with her?  Regardless this is an intriguing example in which these birds brains have become adapted not only to produce complicated vocalizations but also to precisely coordinate with a partner.