Alerting components in animal vocalization

Abstract

Effective communication relies on signals that are detectable and informative, yet the structural acoustic properties supporting these qualities are not always the same. Alerting components (introductory elements that capture the receiver's attention) can enhance signalling efficiency. While such elements are likely to be common in both human and animal communication, standardized evaluation criteria for alerting components are lacking. We propose a framework to identify and evaluate acoustic alerting components based on three criteria. (1) Signal properties: structural features enhancing signal propagation and effective range. (2) Signaller perspective: flexible use by signallers based on receiver attention. (3) Receiver perspective: increased likelihood and speed of responses to the signal. We applied this framework to test whether ‘wail’ elements in rock hyrax, Procavia capensis, songs serve as alerting components. Our findings indicate that wails exhibit several features consistent with an alerting function: they degrade minimally over medium communicative ranges, frequently occur at the beginning of songs and appear less often at the end. Playback experiments showed a higher probability of conspecific responses to songs with intact wails than to songs with reduced wails. Our framework offers a tool to study alerting components across species, revealing strategies for effective communication in complex environments. Understanding the mechanisms underlying the usage and effectiveness of alerting components can provide insights into how animals capture and evaluate attention and the cognitive processes supporting these capabilities.