Is male song quality important in maintaining pair bonds?

This study investigated a possible mechanism for maintaining long-term pair bonds in a socially monogamous songbird, the zebra finch (Taeniopygia guttata). Only males sing in this species. Song is thought to be important in female choice, and our earlier research showed that distortion of song by tracheosyringeal nerve transection (TS) and temporary muting by puncturing the interclavicular air sac (AS) both had profound effects on female's choice of male mates and pair formation. Males continue to sing when paired, though function and importance of this song is not well understood. The current study investigated whether these same vocal manipulations affected the maintenance of pair bonds. A total of 27 males and females formed pairs in aviaries. After 3 weeks of pairing and one week after the start of egg laying, males were experimentally manipulated. Eggs were then removed, so that females were forced to decide whether or not to engage in another breeding attempt with their mate. Novel unpaired males and females were added to the aviaries for potential extra pair copulation partners or new mates and pairs were then observed for four weeks. Only two pairs separated after song-altering surgery (both in the TS group), and one of these TS males quickly paired with another female. Of the pairs that remained together, there were no significant differences in courtship or pairing behaviors compared with control pairs. These results suggest that song quality has surprisingly little effect on female pairing decisions once the pair has formed, and that the song quality mechanisms of pair bond formation are not required in the maintenance of the pair bond.