Hearing Nemo: Alarm Calling Behaviour in a Coral Reef Fish

Abstract

Alarm calling behaviour—the production and use of particular vocalisations that warn of impending danger, and the response to those vocalisations—is a major anti-predator strategy seen in a wide range of bird and mammal species. Receivers of alarm calls that respond adaptively to these acoustic signals obtain fitness benefits through increased survival. Although fish are known to be highly vocal and to use acoustic signals and cues to obtain information about the environment, the potential use of alarm calls has received little empirical attention. This study adapts established terrestrial experimental protocols— combining video and audio recordings and detailed observations with simulated model predator attacks and resulting call playbacks—to explore alarm calling behaviour in the orangefin anemonefish (Amphiprion chrysopterus) in Moorea, French Polynesia. The use of ecologically relevant predator models in this study illuminates the evasive and wary/agitated anti-predator behavioural responses of this highly social species, including on the overall rate of vocalisation. Despite a high degree of variation in responses across individuals and life stages, there was also a trend towards increased response to the initial onset of alarm call playback in isolation of any visual stimulus. Thus, Amphiprion chrysopterus individuals demonstrate the three recognised stages of alarm calling behaviour: call production, call usage and call response. This research deepens our understanding of fish vocal behaviour, identifying the ecological and social contexts in which different sounds are made, and the responses they elicit. More generally, this research reflects the growing interest in understanding how fish species inhabiting coral reefs interact whilst navigating their acoustic environment.