Organization, variation in time, and impacting factors in the song strophe repertoire in the Great Reed Warbler (Acrocephalus arundinaceus)

Abstract

The song of the Great Reed Warbler (GRW) is produced by males before and during the breeding season in territory defense and mate attraction. To date, researchers studying the song of the species have mainly focused on syllable repertoire and its function. In this paper we present first data on the organization of strophes and their possible function in the GRW. We analyzed short- and long-term changes in strophe repertoire size and composition and the relationship between strophe repertoire and male age, philopatry and harem size. Syllables were organized in quite a large but still limited number of strophe types and variants, which were repeated by an individual male in the same or a relatively similar form within a season. Longitudinal analyses revealed significant effects of season and male age on strophe repertoire size. We also found a positive correlation between male harem size and strophe repertoire size. The composition of GRW strophe repertoire was stable within a season but significantly changed between years. At 3-year time intervals, GRW males exchanged more than half of their song types and almost all song variants. The level of between-year changes in song repertoire suggests that the GRW is a species adapted for learning.