Chorus effect

Abstract: SYNOPSIS. Neighboring males in rhythmically calling insects and anurans often chorus in a synchronizing or alternating fashion. Neuroethological investigations of chorusing species reveal that their rhythms are maintained by pacemakers and that a basic interactive algorithm, common to many species, yields the collective synchrony or alternation observed. Traditionally, synchrony has been viewed as a cooperative event. However, recent evidence suggests that a collective synchronous display can also be an incidental outcome of signal “jamming” activities between neighboring males competing to attract females. This arises when female phonotaxis is influenced by a precedence effect in which the first of two or more closely synchronized calls is preferred. Under such circumstances, males are selected to adopt a timing mechanism averting following calls. If males happen to call at comparable rates, the adopted mechanism can yield synchrony as a by-product. Alternation, too, may be produced by a similar mechanism and also represent an epiphenomenon. That alternation, as opposed to synchrony, results may be a mere artefact of the species' solo calling rate, but perceptual constraints may select specifically for alternation in some species.

Abstract: Part 1 Sound questions and acoustic behaviour: alternative behaviours male spacing behaviour mate finding in females size and reproductive success selection on the calling behaviour of insects natural and sexual selection. Part 2 Acoustic strategies in aggregations: calling and co-operating leks and sprees sites for aggregations more numbers more power are females attracted to choruses? group songs and species distinctiveness - individuality in a group male agonistic behaviour with minimum contact. Part 3 Chorusing and alternating behaviour: synchrony within the chorus asynchronous choruses calling and listening crepitation alternation. Part 4 A question of sound: sound a working definition measuring sound near-field sound communication frequency and loudness control measuring substrate vibrations amplifiers and baffles noise. Part 5 Producing sound: using near-field sounds substrate-borne vibration airborne sounds. Part 6 Listening and recognizing: collecting information the mechanoreceptor the locust ears of crickets and bushcrickets moth ears the cicada car strange ears - lacewings, beetles, mantises and bugs. Part 7 Mate recognition: species specific signals homogamy unique species songs the recognition of non-like calling and courtship songs signal stability female songs and species recognition. Part 8 Sound patterns: variations and stereotypes the central control of the output feedback control linking input to output the input signal recognition central recognition song gaps and species recognition in grasshoppers. Part 9 Sound localization and distance perception: directionality in the near-field directional responses to substrate-borne vibration directional responses to airborne sound directional hearing in the Orthoptesa distance. Part 10 Avoiding predation: the detection of predation evolutionary strategies in response to birds and parasitoids calling strategies that reduce predation. Part II The evolution of acoustic communication: sexual differences in calling switching signals and changing meanings dual auditory function in acoustic moths the evolution of social signals conclusion.

Abstract: Predation is an important cost of communication in animals and thus a potent selection pressure on the evolution of signaling behavior. Heterospecific eavesdropping by predators may increase the vulnerability of vocalizing prey, particularly during low light, such as at dusk when nocturnal predators are actively hunting. Despite the risk it entails, dawn and dusk chorusing is common in passerines. However, the dusk chorus has not been studied much, neglecting the opportunity for understanding how eavesdropping between predators and prey may shape communication in birds. Here, we report the first demonstration of simulated predation risk (playback of owl vocalizations) altering the dusk chorus of a diurnal passerine, the veery (Catharus fuscescens). Veeries have a pronounced dusk chorus, singing well after sunset and potentially exposing themselves to predation by owls. In response to brief playbacks of owl calls (~30 s of calls presented three times over 25 min), veeries sang fewer songs post-sunset and stopped singing earlier relative to control trials. These changes in singing remained evident 30 min after the last owl stimulus. Although the avian dusk chorus has received relatively little attention to date, our results suggest that the dusk chorus may pose a higher predation risk to singing males that may influence the evolution of singing behavior in diurnal birds.