| Coordinated vocal signals produced by birds, such as duets and choruses, present a compelling opportunity to investigate the adaptive significance of cooperation and conflict-based behaviours. I studied the form and function of coordinated vocal signals in cooperatively breeding Neotropical Rufous-naped Wrens (Campylorhynchus rufinucha). I examined variation in daily and seasonal vocal output and found that solo and duet songs peak at dawn and decrease thereafter, and that solo song rate, but not duet or chorus song rate, varied across breeding stages. Both sexes have song repertoires, and song sharing decreases with distance between territorial groups. To examine the function of coordinated vocalizations, I played back solos, duets, and choruses to territorial birds to represent varying degrees of threat. Groups responded strongly and similarly to all playback treatments. This study suggests that song may be an important indicator of group identity and that coordinated vocalizations function in cooperative territory defence. |
