Similar, yet different: male Reed Buntings (Emberiza schoeniclus) show high individual differences in song composition, rates of syllable sharing and use

Abstract

Male birds sing to find a mate or to defend a territory. Their songs are known to be highly species-specific, but males may additionally show high levels of song individuality. Differences in song features have been shown to code for male quality and/or motivational states. Quantifying differences and similarities in the singing of males may broaden the general understanding of avian song and pairing systems. Here, we investigated the song of an Eastern German population of Reed Buntings (Emberiza schoeniclus), a species with a medium-sized song repertoire and extraordinary high extra-pair young rates (up to 55 %). Using a computed template-recognition algorithm, we analysed songs of 11 males focussing on individual variation in song composition and use. To determine the degree of song sharing among males, we compared two different measurements of song similarity (DICE coefficient and coefficient of compositional similarity; CCS). We found that males sing highly individual with respect to most analysed parameters. On average, males shared 62 % of their syllable type repertoire with at least one other male. However, taking song use into account, the overall degree of song sharing was low to moderate for both similarity measures, and average DICE values were higher than the CCS values. Additionally, we found that the closer the male territories were to each other, the higher the proportion of song sharing tended to be. We discuss the implications of our findings for the function of song in the Reed Bunting.