White-faced Capuchin

White-faced capuchins produce alarm calls that grade continuously rather than falling into discrete categories. Call acoustic properties vary with threat type, urgency, and caller arousal—creating a multidimensional signal space. Receivers extract information from multiple acoustic dimensions simultaneously, enabling nuanced threat assessment.

The graded system complements categorical information. While some call types distinguish predator categories (snake versus raptor), acoustic variation within categories encodes urgency and proximity. This two-level system—categorical type plus graded properties—provides rich information from simple signals.

Social context affects call production. Capuchins call differently when alone versus with group members, when with kin versus non-kin, and when high-ranking versus low-ranking individuals are nearby. The same predator elicits different calls depending on social audience. Communication isn't purely about predators—it's about managing social relationships through predator-related signals.

Food-associated calls show similar complexity. Capuchins produce calls when finding food that vary with food quality, quantity, and social context. The call system serves multiple functions beyond predator warning, suggesting communication complexity is a general capuchin trait rather than specific to alarm contexts.

For organizations, capuchins demonstrate that signals can encode multiple dimensions simultaneously. Voice tone conveys urgency even when words convey content. Effective communication uses all available channels.