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

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.

Structure and dynamics of mixed‐species choruses in a tropical anuran assemblage: insights from network analysis

“…This indicates that these species were dominant in the chorus and frequently overlapped their calling activity with other species. B. lundii usually calls in the dry season (Duarte et al., 2019), while R . diptycha has a long reproductive season, vocalizing all over the year (Giaretta et al., 2008; Oda et al., 2009).…”

“…A wide variety of vertebrates, such as most anurans and birds, largely rely on acoustic communication for mating (Duellman, 1970; Gerhardt & Huber, 2002). Males usually attend breeding sites to advertise for females and signal territory occupancy, forming loud and dense choruses in which they compete for reproductive mates (Duarte et al., 2019; Wells, 2007). Following classical models of communication (Shannon, 1948) and sexual selection (Anderson, 1994; Gerhardt & Huber, 2002), these choruses have traditionally been considered aggregations of conspecific signallers and receivers (Grafe, 2005).…”

“…The recent development of new remote monitoring techniques, such passive acoustic monitoring, enables to record choruses in a continuous and non‐invasive way (Pieretti et al., 2015; Sugai et al., 2019). Studies have shown that anuran vocalizations and breeding dynamics change over time (Duarte et al., 2019). Temporal patterns of anuran calling and reproductive activity are usually affected by environmental factors, such as humidity, temperature and light intensity (Brooke et al., 2000; Llusia et al., 2013; Ulloa et al., 2019).…”

Patterns of acoustic phenology in an anuran assemblage of the Yungas Andean forests of Argentina

“…Studying these calling patterns, can serve as a tool to define the core calling periods of the species recorded (Lemckert and Mahony, 2008), for which it is considered of utmost importance to increase the detection probability in anuran survey programs. The use of automated recording devices for passive acoustic monitoring techniques (PAM) can add valuable information such as the acoustic breeding patterns, as several species of anurans may breed simultaneously in different reproductive sites (Nelson and Garcia, 2017;Duarte et al, 2019;Ulloa et al, 2019;Pérez-Granados et al, 2020).…”

“…One way to minimize competition for the acoustic space is made effectively by segregating the niche in its temporal and spectral dimensions (Both and Grant, 2012;Sinsch et al, 2012;Guerra et al, 2020, Lima et al, 2019. The temporal segregation of the advertisement calls can be fundamental for the constitution of large anuran assemblages, mainly in breeding areas where several species vocalize simultaneously (Drewry and Rand, 1983;Schwartz and Wells, 1983;Bertolucci and Rodrigues, 2002;Duarte et al, 2019).…”