Summary: Kunc et al. (2006)

It is thought that overlapping of song in birds is a signal of immediate aggression. However, some evidence suggests that song overlapping may provide information to females about a male's quality, allowing them to make extrapair mating decisions based on male vocal performance (eavesdropping). Kunc et al. (2006) investigated how male behaviour (overlapping versus non-overlapping) influenced subsequent pairing status and how males respond to playbacks of vocalizations, using specific structural song components. They predicted that more successful males would overlap songs more if song is a signal of male quality. They found that males that mated during the breeding season overlapped their songs more to the playback than males that remained unpaired, suggesting that overlapping is a signal of male status. They also found that males adjusted the use of specific song components and decreased song rate, suggesting that flexibility of structural song components is more important than increasing song output. Since song overlapping may be a signal of aggression, Kunc et al. (2006) suggested that more aggressive males may have greater pairing success.