Whitethroats Sylvia communis have very elaborate song element repertoires. The song repertoire reflects male quality in terms of age and wing length, and high-repertoire males were more likely to mate than low-repertoire males. In this experiment the meaning of different motif song repertoire sizes to unmated males was investigated by playback experiments. Each male was presented with three different playback stimuli: high repertoire, low repertoire, and low repertoire with songs elongated by repeating the last elements of each song to the length of high repertoire songs. The difference in the total number of elements presented between low and high repertoire playback arose since the main part of the variation in motif songs were presented in the last part of the song. Approach measures, time spent near speaker and song activity in response to playback will be examined in relation to the different playback stimuli. Furthermore, the response to the different playbacks will be considered in relation to the males' own song element repertoire in the post-playback period. The risk of losing a competition for territory or attraction of females may depend on the repertoire size of the male relative to that of the intruder's repertoire size.
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