Captive-born cotton-top tamarins (Saguinus oedipus) respond similarly to vocalizations of predators and sympatric nonpredators

What types of cues do callitrichid primates use to detect and respond to predators? Do they respond to predator-specific cues or to more general cues? The evidence for these questions remains conflicting. We presented captive-born and reared cotton-top tamarins with no previous exposure to predators (or predator cues) with vocalizations from three potential predators of cotton-top tamarin in the wild (white hawk, jaguar, and tayra) and with vocalizations from sympatric nonpredators (black-faced antthrush and red howler monkey). Vocalizations from predators and from nonpredator mammals elicited equivalent arousal, fear, and vocal responses. Howler monkey roars produced the strongest responses. The results suggest that predator-naïve cotton-top tamarins do not recognize specific predator vocalizations, but may respond to vocal qualities (low-frequency, noisy sounds) that indicate large body size, threat, or aggression. On the other hand, tamarins responded much more strongly to the higher frequency calls from the hawk than the antthrush, suggesting another mechanism must also be involved. The failure of captive-reared tamarins to distinguish between vocalizations of predators and nonpredator mammals has important implications for reintroduction studies.