Structure and complexity of perched and flight songs of the tree pipit (Anthus trivialis)

We analysed 2166 songs of 90 males of the tree pipit (Anthus trivialis; Passeriformes: Motacillidae) from five Czech localities to evaluate variation in song characteristics, the song structure and syntax rules, and differences between songs performed in flight and from perches. We measured temporal and spectral song characteristics; structure analysis was based on the identification of individual syllable units. There was a high among-population variation in the repertoire, suggesting substantial differences in local dialects. Flight and perched songs significantly differed in most analysed quantitative characteristics. While both types of songs are apparently used in territorial defence, trill elements within flight songs may also indicate male quality to potential mates. Characteristic bi-syllable repeats within songs were often unique for individual males and may function in individual recognition. Features of tree pipit songs make it a good species for studying song variation and function in birds with complex repertoires.