Communication about potentially harmful foods in free-ranging chacma baboons,Papio ursinus

Abstract

Marked avoidance responses to fruit drugged with cynalin, viewed in this investigation as a potentially harmful food, were observed during attempts at trapping some free-ranging Chacma baboons,Papio ursinus. The sub-adults and juveniles displayed the most interest to the fruit, but in most cases they were threatened away by the high ranking male. Eventually the fruit was ignored altogether which suggested that social communication behaviour manifested in a network of threat-avoidance responses by conspecifics is highly adaptive to a baboon troop because it is a more efficient and safer means of assessing the quality of edible items than is individual experience. Different findings were reported byFairbanks (1975) in an investigation involving some free-ranging red spider monkeys,Ateles geoffroyi, and some captive pig-tailed macaques,Macaca nemestrina. This investigator was unable to find evidence that social communication was used to assess food quality in these two species. The difference in findings of these two investigations are explained by assuming that selective pressures which place premiums on social food quality assessment are stronger among primates who exploit more open habitats with a wider variety of food resources than with primates living in more restricted areas where food variety is limited to only a few staples.