Toque Macaque

Toque macaques produce distinct alarm calls for different predator classes—aerial versus terrestrial—similar to vervets but in a different geographic and ecological context. This parallel evolution demonstrates that referential alarm systems evolve repeatedly when predation pressure from multiple predator types is high. The communication solution is convergent.

Audience effects modulate calling. Males call more when females are present, especially females with infants. This isn't simple alerting—it's strategic communication that considers who benefits from the information. Males who call protectively may gain mating advantages through female choice for protective partners.

Call variants encode urgency within categories. Beyond the aerial/terrestrial distinction, call acoustic properties vary with predator proximity and behavior. Close, attacking predators elicit more urgent variants than distant, stationary ones. Receivers extract both categorical (what kind) and quantitative (how urgent) information.

Juveniles must learn appropriate responses. Young macaques initially respond inappropriately to alarm calls—sometimes approaching predators. Adults provide corrective feedback through their own responses. The system requires social learning, not just innate recognition.

For organizations, toque macaques illustrate that alarm systems evolve when the information value exceeds signaling costs. When threats are diverse and responses must be specific, investing in detailed warning systems pays off.