Male red-winged blackbirds (Agelaius phoeniceus) respond to playback of conspecific song on their territories with the song spread, a graded aggressive display in which males extend their wings to expose their red epaulets while singing. We show that the intensity of song spread display declines with repeated presentation of one song type, and recovers when song types are switched. Recovery is greater for switches between song types that are acoustically dissimilar than for switches between song types that are acoustically similar. Recovery is no different for switches between two song types taken from the repertoires of different males than for switches between song types recorded from the same male. Analysis of acoustic features also indicates that song types recorded from different males are not more dissimilar than are song types from the same male. Our results do not support the idea that repertoires of red-winged blackbirds are composed of similar song types in order to facilitate individual recognition. Rather, repertoires may be constructed of dissimilar song types, so as to help maintain the response of listeners despite habituation.