SONG ANALYSIS OF THE SOUTH AMERICAN THRUSHES (TURDUS) IN RELATION TO THEIR BODY MASS IN A PHYLOGENETIC CONTEXT

LAVINIA OBLANCA PABLO DAMIÁN; TUBARO PABLO LUIS

ORNITOLOGIA NEOTROPICAL

NEOTROPICAL ORNITHOLOGICAL SOC

Lugar: Bonn; Año: 2012 vol. 23 p. 349 - 365

1075-4377

Bird song is one of the most studied examples of animal behavior diversification because of its role in communication and its function in premating reproductive isolation. There is a well-known negative relationship between bird body size and song frequency that has been identified as a vocal constraint playing a role in song evolution. Here we assessed the influence of bird body mass in the frequency and temporal features of the song of the South American Turdus thrushes, recognized by their complex and variable vocalizations. Songs from 137 individuals from 25 species were compared, and four temporal and five frequency features were measured on each spectrogram. The effect of body mass on these variables was analyzed through phylogenetically independent pairwise comparisons, based on the phylogenetic hypothesis of Voelker et al. (2007). Our results showed a clear negative relationship between song emphasized frequency and body mass, also reported in other groups of birds, that could be related to both anatomical and physiological features of the syrinx and the vocal tract anterior to the vocal organ. As other selective forces could be shaping the song structure, we discuss some of them and their implications for our results.