The effect of neighbours and females on dawn and daytime singing behaviours by male chipping sparrows

Bird song may play an important role for communication among territorial neighbours, but the effect of neighbours on song use is still not well known. My previous field observations suggested that male chipping sparrows, Spizella passerina, use the dawn chorus for interactions among neighbouring males, and use day song for female attraction. To determine how these social factors may influence dawn and daytime singing behaviour, I conducted a series of experiments in which I removed the male neighbours or the female mate of territorial males during 1998-2000. Following removal of all neighbouring males, the solitary male either stopped or reduced his dawn chorus (N=9), but did not change his daytime singing behaviour. After one of the neighbouring males was returned to his territory, the focal male resumed and increased his dawn bout, accompanied with close-range countersinging. Following the removal of a territorial maleʹs mate, the widowed male did not change the dawn chorus, but significantly increased his day song. This study thus revealed that, in chipping sparrows, the presence or absence of neighbouring males has a significant effect on the dawn chorus singing behaviour of territorial males. The presence or absence of a maleʹs mate, in contrast, has a strong influence on a maleʹs daytime singing behaviour. This study also supports the hypothesis that the dawn chorus and daytime song have different functions.