Spatial location influences vocal interactions in bullfrog choruses

Abstract

A multiple sensor array was employed to identify the spatial locations of all vocalizing male bullfrogs (Rana catesbeiana) in five natural choruses. Patterns of vocal activity collected with this array were compared with computer simulations of chorus activity. Bullfrogs were not randomly spaced within choruses, but tended to cluster into closely spaced groups of two to five vocalizing males. There were nonrandom, differing patterns of vocal interactions within clusters of closely spaced males and between different clusters. Bullfrogs located within the same cluster tended to overlap or alternate call notes with two or more other males in that cluster. These near-simultaneous calling bouts produced advertisement calls with more pronounced amplitude modulation than occurred in nonoverlapping notes or calls. Bullfrogs located in different clusters more often alternated entire calls or overlapped only small segments of their calls. They also tended to respond sequentially to calls of their farther neighbors compared to their nearer neighbors. Results of computational analyses showed that the observed patterns of vocal interactions were significantly different than expected based on random activity. The use of a multiple sensor array provides a richer view of the dynamics of choruses than available based on single microphone techniques.

Acoustic localization of terrestrial wildlife: Current practices and future opportunities

“…Ambiguous DOA solutions can occur when using fewer than the recommended number of microphones, but other information about the source's position can be used to eliminate uncertainty. For instance, Bates et al (2010) recorded frogs using two ARUs that each had two microphones. This setup alone would not have identified a coordinate solution, but the animals were known to be calling from the surface of a pond on one side of the ARUs, allowing a unique solution to be found by process of elimination.…”

“…The intermicrophone distance for DOA arrays was between 3 and 12 cm, except in one study which compared an ARU with 61 cm microphone spacing to a more typical 4 cm intermicrophone distance (Wang et al, 2005). Multimicrophone ARUs for DOA localization were often arranged in more complex three‐dimensional geometries than the multimicrophone ARUs used for bat localization (but see Bates et al, 2010). Examples include a ring of microphones with one microphone above the plane of the ring (Suzuki et al, 2017) or four microphones positioned at the corners of a tetrahedron (e.g., Voxnet, Cai et al, 2013).…”

“…Automated methods used for sound detection included a variety of amplitude‐based triggering methods (e.g., Bates et al, 2010; Collier, Blumstein, et al, 2010; Eastman & Simmons, 2005), machine learning (Spillmann et al, 2015, 2017), template matching or cross‐correlation (e.g., Araya‐Salas et al, 2017; Frommolt & Tauchert, 2014), and MUSIC (MUltiple SIgnal Classification) methods (e.g., Suzuki et al, 2017, 2016). Automated methods may produce false negatives, where the method does not detect all relevant vocalizations, and false positives, where the method detects nontarget sounds.…”

“…The previous paragraph describes a two‐stage approach, which involves the direct calculation of TDOAs. Among two‐stage approaches, two algorithms were used: a direct model of the human auditory system (Bates et al, 2010; Simmons et al, 2008) and an unspecified DOA approach (Schul et al, 2000). The seventeen remaining approaches were one‐stage methods, which do not require explicit calculation of TDOA.…”

Impact of group size and social composition on group vocal activity and acoustic network in a social songbird

“…But most of the time, group vocal productions have been considered as by-products of individuals' simultaneous but not necessarily coordinated vocalizations. For example, this noisy sound can result from the activity of up to thousands of individuals in choruses of birds (Burt & Vehrencamp, 2005), insects (Greenfield, 1994), frogs (M. E. Bates, Cropp, Gonchar, & Knowles, 2010;Jones, Jones, & Ratman, 2009;Marshall, 2003;Simmons, Bates, & Knowles, 2009), as well as in fish communities (D'spain & Berger, 2004;Locascio, 2004;Locascio & Mann, 2005;Mann, 2003), colonies of nesting birds (Adret-Hausberger, 1982;Mathevon, 1997) or breeding marine mammals (Schusterman, 1978;Southall, Schusterman, & Kastak, 2003). This sound resulting from a group of individuals vocalizing simultaneously has mainly been viewed as a source of noise pollution constraining the pairwise communications (Aubin & Jouventin, 1998;Gerhardt & Klump, 1988).…”