Proximate factors mediating ‘contact' calls in adult female baboons and their infants

"Contact" calls are widespread in social mammals and birds, but the proximate factors that motivate call production and mediate their contact function remain poorly specified. Field study of chacma baboons (Papio cynocephalus ursinus) revealed that contact barks in adult females were motivated by separation both from the group at large and from their dependent infants. A variety of social and ecological factors affect the probability of separation from either one or both. Results of simultaneous observations and a playback experiment indicate that the contact function of calling between mothers and infants was mediated by occasional maternal retrieval rather than coordinated call exchange. Mothers recognized the contact barks of their own infants and often were strongly motivated to locate them. However, mothers did not produce contact barks in reply unless they themselves were at risk of becoming separated from the group.

The function and mechanisms underlying baboon contact barks
Free-ranging baboons, Papio cynocephalus ursinus, in the Okavango Delta, Botswana, often give loud ‘contact' barks when separated from other group members. Although these calls appear to function to maintain contact between widely dispersed animals, individuals apparently do not give contact barks with the intent of informing others of their location. Females are more likely to give a contact bark in the 5 min after they themselves have called than in the 5 min after another female has called. Playback experiments suggest that females primarily ‘answer' their close relatives' contact barks when they themselves are separated from other females or at the end of the group progression.

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