Effect of anthropogenic city noise on the vocalizations of four disparate forest birds

The impact of urbanization on biodiversity is often underestimated, as in the case of noise pollution generated by anthropic activities. Birds inhabiting urban and peri-urban areas are exposed to noisy environments that make communication difficult. We evaluate how anthropogenic sounds associated with urbanization (automobiles, airplanes, and helicopters) affect the song of four disparate bird species of the Andean-Patagonian Forest: The Thorn-tailed Rayadito( Aphrastura spinicauda ), the White-crested Elaenia ( Elaenia albiceps ), the Green-backed Firecrown( Sephanoides sephanoides ) and the Austral Parakeet ( Enicognathus ferrugineus ). Between October 2021 and February 2022 we placed audio recorders (AudioMoth v 1.2.0) in wooded areas of a city surrounded by a National Park, in Argentine Patagonia. We selected groups of recordings where an individual was vocalizing before, during and after the occurrence of anthropogenic noise. From each recording, we analyzed frequency (minimum, maximum and dominant frequency) and temporal bioacoustic parameters (duration of vocalization and pause length between syllables). We found that all birds were affected by anthropogenic noise, but bird responses varied between species. Frequency bioacoustic parameters changed during the disturbance in two of the species studied, and all the birds modified at least one of the temporal bioacoustic parameters during the anthropogenic noise. Our results showed how noise produced by human activities affected sound communication, and therefore the behavior of birds. Given the increase in urbanization over recent decades, and consequently in anthropogenic sound, noise pollution should be considered as a disruptor for bird communication and potentially a threat, even in low populated and protected areas.