How infant vervet monkeys learn to recognize starling alarm calls: The role of experience.

Natural observations and field playback experiments were conducted on five groups of free-ranging vervet monkeys to determine when infants recognize the alarm calls of starlings as general alerting signals. Results show that infants do not recognize starling alarm calls at birth. Recognition of starling calls emerges gradually and age at recognition is affected by differences in auditory environment. Infants who have heard starling alarm calls at high rates respond at an earlier age than infants who hear calls at low rates. More importantly, in those groups where infants respond at an earlier age, starlings give alarm calls to vervet predators more often than to non-vervet predators. Thus in the former groups, when adults respond to starling alarm calls, their behavior is more positively reinforcing than in the other groups where starling alarm calls are commonly given to non-vervet predators.