The evolution of song structure in southern African birds: an assessment of the acoustic adaptation hypothesis

Abstract

Song is critical to territory defence, mate attraction, and both species and individual recognition. According to the Acoustic Adaptation Hypothesis (AAH), habitat structure may exercise a selective force on vocal evolution such that song evolves to minimise the degradation and attenuation of acoustic signals in the particular habitat in which a species has evolved. We conducted a comparative survey of the songs of 40 South African passerine species to test the generality of the AAH. We compared pairs of congenerics, one from closed and one from grassland habitats, for seven different song attributes, including frequency, bandwidth, structure and temporal parameters. We controlled for phylogenetic effects by assessing differences between pairs of related individuals. The survey did not support the predictions of the AAH.