A natural orchestra: how are anuran choruses formed in artificial ponds in southeast Brazil?

Abstract

Abstract Choruses are commonly observed phenomena in both terrestrial and aquatic environments and are the product of species vocalizing contemporaneously usually at dawn and dusk. This study analyzes the composition and temporal distribution of anuran choruses at a recently built artificial pond in Southeast Brazil. Data were collected using Passive Acoustic Monitoring devices set to record 24-hours per day, seven days a month, throughout an entire year (October 2016 to September 2017). A total of eight species participated in the studied choruses: Boana albopunctata , Boana faber , Boana lundii , Phyllomedusa burmeisteri , Physalaemus cuvieri , Rhinella ornata , Rhinella diptycha and Scinax aff. perereca . The number of species, call emission rate, temperature, and humidity were all higher before midnight and during the rainy season. The species differed significantly in mean call rate by hour at which they sang. Boana faber and B. albopunctata were the species with the greatest vocal activity in both seasons, and were predominantly responsible for initiating choruses in the rainy season, while R. diptycha and B. lundii initiated choruses in the dry season. Anuran choruses started around 18:30 h during the rainy season and varied according to the time of sunset, while they started later in the dry season and were not correlated with sunset time. There was a positive correlation between the number of species calling and the call emission rate per month in both seasons. The results show that the choruses were correlated with climatic factors and that the species distributed their vocalizations over time, thus reducing acoustic overlap.