Response of Male Song and Swamp Sparrows To Neighbour, Stranger, and Self Songs

We examined the responsiveness of territorial male swamp sparrows (Melospiza georgiana) and song sparrows (Melospiza melodia) to neighbor, stranger, and self songs. In two speaker tests (with two song bouts played simultaneously from separate speakers), male swamp sparrows failed to discriminate between neighbor and stranger songs and between self and stranger songs. In single speaker presentations, male swamp sparrows responded more aggressively to stranger song than to neighbor song and gave intermediate responses to self song. Male song sparrows showed no significant discrimination between neighbor, stranger, and self songs. We hypothesized that male birds may learn what other conspecific songs should sound like by listening to their own songs. In its most stringent form this hypothesis might predict maximal responsiveness to playback of a male's own song. This prediction was not verified for these two sparrow species. There was less of a difference in responsiveness toward neighbor and stranger songs in song sparrows than in swamp sparrows; this result is compatible with the hypothesis that larger repertoires make neighbor recognition more difficult.