Behavioral responses to species‐specific warning calls in infant squirrel monkeys reared in social isolation

Six infant squirrel monkeys were reared in social isolation. They responded differentially to playbacks of two species‐specific alarm calls. The reaction to the alarm peep, the warning call to bird predators, was a prompt flight to the mother surrogate and essentially resembled the respective behavior of mother‐reared infants. The responses to yapping, the alarm call to terrestrial predators, were less clear‐cut and habituated soon. However, when yapping was played back in connection with the presentation of a reference object, both subjects tested in this way clearly avoided the object and preferred contact with the mother surrogate while they thoroughly explored an object presented with a control tone. From this it can be concluded that the perception of both alarm calls is innate. In addition, the method of behavior‐contingent playback of vocalizations simulates the learning process by which the visual perception of terrestrial predators of the habitat is acquired.