Specific Recognition in the Song of Bonelli's Warbler (Phylloscopus Bonelli)

The analysis. The song of territorial proclamation of P. bonelli has shown that the most stable parameters were the duration of the song, the number of units constituting them, the lower limit of the acoustic spectrum, and the form of certain elements. The most fluctuating parameters were the factors of duration of sequences and silences between songs, the rhythms in the songs, the upper limit of the acoustic spectrum, and to the form of certain sub-units. The experimentation. The experimentation shows us that the species are not always constituted by the least variable parameters. The most important species for this bird are: the sense of the frequency modulation against time, the distribution of acoustic energy in the lower part of the spectrum, the purity of the frequencies, and a sufficient duration of the signal. We have introduced the notion of rejection markers permitting the bird to reject some signals close to their own, by deciding rapidly and without ambiguity which behaviour to adopt. In the case of P. bonelli as an example we have discussed the relations existing between the individual variability and the fixity of species characters. We have concluded that it is a question of two aspects of the same phenomennon.