Bird phonology and species recognition: minimal song units are cues inducing strong reactions in male cirl buntings (Emberiza cirlus)

Abstract

Cirl bunting (Emberiza cirlus) songs consist of identical repetitions of the same syllable. A syllable is an arrangement of minimal acoustic units, which I call elements. A limited number of elements characterizes the different kinds of syllables found in the repertoires of individuals from different areas. The three most frequent element categories (a, b and c) represent 80% of all syllable elements. I demonstrate that minimal song units from these three categories are strong cues for species recognition because (1) songs composed of repetitions of only one of these elements (a or b or c) induced strong responses, while the repetition of a heterospecific element induced very weak responses; and (2) a song composed of the elements a, b, and c ordered at random without the usual syllable syntax induced the same reactions as a normal control song with the same elements ordered in a normal syntactical pattern. These results also demonstrated that while normal syntax is not required, normal variety appears to...