In many song birds, song repertoire size correlates with male quality and can vary with age. Many species have pronounced changes in repertoire size and composition especially between first and second season. This holds true also for Common nightingales Luscinia megarhynchos a species with large song type repertoires. One function of such pronounced changes between year one and two might be an adjustment to the ‘popular’ song types in the breeding grounds. As part of a long term field study we investigated whether nightingales adjust their song type repertoires to the song types commonly sung in their breeding population. We analysed nocturnal song of individuals in their first and subsequent breeding season. We compared the repertoire composition of these birds with the ‘popular’ song types in the breeding ground and addressed whether such ‘popular’ song types were permanent, added, or dropped from first to second breeding season of our target birds. Furthermore, we compared repertoire similarity of first year nightingales’ repertoires with the population repertoires to the same measure for these birds in their next year. Our data suggest that nightingales adjusted their singing to the songs in the breeding grounds by maintaining common and frequently sung song types which resulted in increased similarity to the population repertoire. Song type matching among males and female song preferences will be discussed as potential underlying functions of such repertoire adjustment.
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