Matching of acoustic features during the vocal exchange of coo calls by Japanese macaques.

A central issue in studies of vocalizations of non-human primates is the extent of their plasticity. Japanese macaques, Macaca fuscata, frequently utter coo calls and exchange these calls with other group members to maintain contact vocally. I conducted a playback experiment to examine whether monkeys that respond vocally match the acoustic features of their reply to those of the calls they have heard. Six to eight stimulus calls with different acoustic properties in terms of fundamental frequency components were played back to each of seven females, in an attempt to elicit replies from the subjects. There were significant positive regressions of the frequency range of stimuli with that of the replies. Japanese macaques thus matched some of the acoustic features of their replies to those of the preceding calls, suggesting that they might be able to modify the acoustic features of their calls according to the features of the prior calls of another group member.Copyright 1998 The Association for the Study of Animal Behaviour Copyright 1998 The Association for the Study of Animal Behaviour.