Acoustic adaptations to anthropogenic noise in the cicada Cryptotympana takasagona Kato (Hemiptera: Cicadidae)

Anthropogenic noise produced by human activities affects acoustic communication in animals living in urban habitats. We recorded the calling songs of the cicada Cryptotympana takasagona in the Kaohsiung metropolitan areas of southern Taiwan to investigate possible acoustic adaptations to anthropogenic noise. C. takasagona did not call more in noise gaps. Acoustic features (peak frequency, quartile 25%, quartile 50%, and quartile 75%) of calling songs significantly increased with ambient noise levels. C. takasagona shifted the energy distribution of calling songs to higher frequencies in the presence of higher noise levels. We suggest that the acoustic adaptation by which song frequencies increase with levels of anthropogenic noise in C. takasagona may result from a size-dependent calling strategy in which small-sized males call more in noise conditions or large-sized males adjust their song frequency by changing their abdominal cavities.