Song repertoire variability in the reed bunting Emberiza schoeniclus [abstract]

Giuliano Matessi, Alessandro Grapputo, Andrea Pilastro and Guglielmo Marin (1997). Song repertoire variability in the reed bunting Emberiza schoeniclus [abstract]. Bioacoustics, Volume 8 (3-4): 269

The reed bunting Emberiza schoeniclus is a passerine belonging to the family Emberizidae, widely distributed in the Palearctic region, mainly in marshes and reedbeds. This species includes several forms, grouped in three main subspecies: E. s. schoeniclus, intermedia and pyrrhuloides. These differ slightly in size and colour and highly in bill shape and size. A high intraspecific polymorphism for bill size is rather uncommon in passerines; it has been shown that this variation is genetically determined and often involves an extension of the trophic niche. We analysed the genetic and morphologic variation within and among populations of E. s. schoeniclus (the small bill, migrant form that breeds in central Europe and marginally in north Italy) and E. s. intermedia (the large bill, mainly resident form that breeds in several locations throughout Italy). During winter the subspecies are sympatric in northern Italy. The separation in bill morphology was reflected in a separation in genetic variability. We are interested in finding the forces that could maintain this separation. One could be a difference in song repertoires. Models of cultural evolution, similar to genetic models, can be used to explain the formation and stability of local dialects. Morphological, genetic and cultural evolution can be compared to explain this species' population structure. We recorded songs from individuals of the two subspecies breeding in two different localities in northern Italy. The songs were translated into sonograms and these were compared over a range of variables. A catalogue of syllable types was built grouping the syllables according to qualitative sonogram similarity. The songs of the two subspecies were significantly different in bout length and average number of repeated syllables. We built a syllable sequence distance matrix, using the catalogue to count the number of shared syllable types, and performed cluster analysis, but this did not separate the two populations. We intend to spread the analysis to other populations in Europe, characterize songs with more detail, use quantitative methods to create the syllable type catalogue and refine the syllable sequence analysis in order to build a cultural evolution model.