Soundscapes of the Yungas Andean forest: Identifying the acoustic footprint of an anuran assemblage

Abstract

Soundscapes are composed by the conjunction of sound patterns in each space and time. The biophony produced by the advertisement calls of anurans are one of the most outstanding features of a soundscape, particularly in subtropical montane areas such as the Yungas Andean forests of NW Argentina. We recorded soundscapes with automated recording units along an altitudinal gradient and throughout a whole year in the Calilegua National Park. Using a novel combination of visual analysis and acoustic indices we have been able to identify the anuran acoustic fingerprint in the soundscapes of a seasonal subtropical montane forest. In addition, we detected a decrement in using the acoustic communication channel along the altitudinal gradient by anuran assemblages, in agreement with a decrement in species richness. Our results showed a seasonal effect of the vocalization patterns, splitting the group of sounds recorded in two main periods along the year. In this study we presented the first description of Argentina's altitudinal strata of the Yungas Andean forests. This information provides a solid basis for monitoring programs of direct and indirect anthropogenic impacts. Additionally, we highlight the importance of understanding how soundscapes are composed in a naturally protected area and, posit them as a novel ecosystem service that could benefit human health. We emphasise that Natural Soundscapes should be protected and must be included as intangible heritage in the management plans of protected areas in the country. Likewise, the methods proposed in this study encourage settling down the basis for implementing long-term acoustic monitoring of anuran species and other acoustic communities in the Yungas ecoregion.