Habitat density, song structure and dialects in the Madagascar paradise flycatcher Terpsiphone mutata

Bird song is an important signal for long-distance intraspecific communication. Thus, song characteristics are expected to have undergone adaptive modification to maximise propagation through the environment. Acoustic properties of song should be correlated with the habitat in which they are broadcast, and neighbouring individuals should sing similar songs because they share the same local acoustic environment. We tested these predictions by investigating associations between habitat characteristics and song attributes in the Madagascar paradise flycatcher Terpsiphone mutata . We also examined whether song dialects were distributed non-randomly through the study site and which features of habitat density best explained these associations. We found that individuals on territories in denser habitat sang longer songs at lower frequencies. Features of song structure were related to both understorey and canopy cover density. The distribution of dialects within the study site was also strongly associated with variation in understorey cover. These findings suggest that habitat variation contributes to maintaining microgeographic variation in song structure in this species.