Structure and repertoire variation in ortolan bunting (Emberiza hortulana L.) from isolated Norwegian population

This paper describes song structure and repertoire variation in ortolan buntings (Emberiza hortulana) from an isolated and declining Norwegian population, analysed by using the minimal unit of production approach. Males from the studied population sang strophes similar to both dialects found in geographically closest populations in Sweden. We did not observe any simplification of song structure, which is typical for isolated populations of birds. On the contrary, the studied population was characterised by a greater song variation. Song type repertoires were larger both at the individual level and if we considered numbers of different syllables and song types found within the population. This variation seems to reflect the influence of habitat fragmentation and female deficiency at the boundary of the species range on song learning processes and males’ dispersion. We also found a remarkable within-song-type variation, which seems to be independent of song type variation level of song production, but its function is unexplained.

Osiejuk, T. S., Ratyska, K., Cygan, J. P. & Dale, S. 2003, Ann. Zool. Fennici 40: 3-16