Abstract

Vocal communication involves the transfer of information between individuals through acoustic signals. In urban environments, these signals often encounter challenges that can impede effective communication. According to the Acoustic Adaptation Hypothesis (AAH), sound transmission varies across habitats and selection is expected to favour vocalisations that maximise signal propagation in a given environment. To evaluate the relevance of the AAH in the territorial song of the Austral Thrush (Turdus falcklandii), a common species in urban areas, we analysed six bioacoustics parameters relevant to communication in urban areas of Concepci & oacute;n, Chile and assessed their association with four disturbance variables related to urban development that could influence vocal communication: ambient noise (dB), vegetation cover (degrees%o), built-up area (degrees%o) and building height (m). Our results showed no significant relationship between urban disturbance variables and spectral parameters (minimum frequency, maximum frequency, peak frequency) or song duration of Austral Thrush territorial songs. However, ambient noise level significantly affected the temporal delivery rate of song elements: birds in noisier environments sang with faster element rates. Ground cover type also influenced element rate, with birds in bare soil areas singing approximately 0.46 elements/s faster than those in grass-dominated areas. These findings suggest that the Austral Thrush maintains consistent spectral song characteristics across urban disturbance gradients, while modifying the temporal structure of song delivery, representing a previously undocumented behavioural adjustment to urban acoustic conditions in this species.