Microgeographic variation in corn bunting (Miliaria calandra) song: Quantitative and discrimination aspects

Geographic variation in bird song that is described as local song dialects refers to a mosaic pattern of distribution of songs in a population within the dispersal capacities of the species. Corn buntings (Miliaria calandra) in the region of Alentejo, Portugal, show such local dialects. However, an interesting aspect of this population is that song types an restricted to s ub-groups of males within each dialect rather than all males singing all so ng types as in other populations. After describing the pattern of song type variation qualitatively (i.e. cla ssifying spectro grams by eye), we used cross-correlation of spectrograms i n quantitative comparisons. This confirmed the qualitative classification o f songs into song type categories and showed a tendency for neighbouring ma les to have most similar songs. Males did not respond significantly more or less strongly to playback of different song types; however males clearly d iscriminated between different song types in a habituation paradigm.