Emotional contexts influence vocal individuality in ungulates

For group-living animals, such as most ungulates, the ability to recognize members of one's social group is crucial. While vocalizations often carry cues to identity, they are also affected by the affective state of the caller, and signals often become more chaotic in contexts of negative valence or high arousal. How does this influence vocal individuality, and is there a pattern across taxa? In order to understand how the individual information content is maintained in emotionally charged contexts, we studied contact calls that were positive or negative in valence in seven ungulate species (cattle, goats, sheep, pigs, wild boars, horses and Przewalski's horses). The information content of these calls was assessed using (1) Beecher's information statistic and (2) the potential of individuality coding (PIC). Across species, calls produced in negative-valence contexts contained less individual information than those in positive-valence contexts. Nevertheless, each species exhibited at least one acoustic parameter that reliably signalled individuality across emotional states. Our findings indicate that negative valence overrides individual information in ungulate vocalizations at least to some extent, and imply that individual vocal recognition may require acoustic stability in certain important parameters, which vary depending on the species. These findings reveal a nuanced role of affective communication and show how emotional expression interacts with the informational content of vocal signals used to maintain social bonds among socially complex animals. • Interaction of vocal individuality and emotional valence was studied in 7 ungulates. • Positive calls carried more identity information than negative ones. • Which parameters kept high PIC values across contexts was species-specific. • This indicates a pattern of vocal identity-valence interaction across species.