Acoustic monitoring of anuran communities in road noise disturbed soundscapes

Abstract

Vocalisation is the main form of communication in frogs. These signals have different social structures and functions. Road noise has increased over the past few decades to the point where it can mask acoustic signals with impacts for animal communication. Anurans are sensitive to noise masking, but few studies have investigated how noise impacts their vocal behaviour. Here, we compared noise levels and activity, as well as calling activity and richness of aurally-identified species, between two sites; one near and one far from a road. We also assessed the potential of noise masking. Noise was significantly higher at the site near the road and during the day at both sites, while vocalisations were more frequent at the far site and during the night. Species richness and composition was the same at both sites, however, Boana albopunctata, B. cipoensis, and Scinax curicica had greater vocal activity at the far site while S. squalirostris, Leptodactylus jolyi, and Dendropsophus minutus had greater vocal activity at the near site. Traffic noise was found to overlap with the frequencies occupied by vocalisations. Since many natural areas around the world are bordered by roads, we emphasise the importance of establishing regulations for the control and monitoring of road noise. Keywords: Anurans, vocalisation, passive acoustic monitoring, noise pollution