Organization of song of the Yellow-rumped flycatcher (Ficedula zanthopygia, Muscicapidae, Aves)

Birdsong consists of stereotypical song types or syllables which follow each other according to certain rules. Based on these rules, linear and combinatorial syntaxes are identified. The former one implies a fixed sequence of song types repeated cyclically. In the combinatorial syntax, there are clusters of song types, within which song types may be performed in a varying sequence. The structure and organization of birdsong have been described for many species, but still remain unexplored for most of them. We studied for the first time the song structure and organization, as well as song sharing for the Yellow-rumped flycatcher Ficedula zanthopygia (Hay, 1845). First of all, we determined the repertoire of song types in each male. Then, the organization of singing was analyzed using methods of information theory and network analysis. To analyze the patterns of song sharing, we compared all song types of all males. Individual repertoires consisted from 8–31 song types. While singing, male flycatchers avoid repeating the same song type two or more times in a row (continuous variety). At the same time, different song types alternate with a much degree of freedom: we did not reveal any patterns which could indicate the presence of either linear or combinatorial syntax. Males generally shared few song types, and the similarity of the repertoires of any two males was small. Besides, males did not preferably use shared or individual (i.e., found in the only one male) song types. Song sharing was not related to the distance between males. The results were compared to what is known about the song structure and organization of the other three Ficedula species studied to date.