%0 Journal Article %A Crockford, Catherine %A Gruber, T. %A Zuberbühler, K. %+ Chimpanzees, Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Max Planck Society %T Chimpanzee quiet hoo variants differ according to context : %G eng %U https://hdl.handle.net/21.11116/0000-0001-3715-A %R 10.1098/rsos.172066 %7 2018-05-01 %D 2018 %8 01.05.2018 %* Review method: peer-reviewed %X In comparative studies of evolution of communication, the
function and use of animal quiet calls have typically been
understudied, despite that these signals are presumably under
selection like other vocalizations, such as alarm calls. Here,
we examine vocalization diversification of chimpanzee quiet
‘hoos’ produced in three contexts—travel, rest and alert—
and potential pressures promoting diversification. Previous
playback and observational studies have suggested that the
overarching function of chimpanzee hoos is to stay in contact
with others, particularly bond partners. We conducted an
acoustic analysis of hoos using audio recordings from wild
chimpanzees (
Pan troglodytes schweinfurthii
) of Budongo Forest,
Uganda. We identified three acoustically distinguishable,
context-specific hoo variants. Each call variant requires specific
responses from receivers to avoid breaking up the social
unit. We propose that callers may achieve coordination by
using acoustically distinguishable calls, advertising their own
behavioural intentions. We conclude that natural selection
has acted towards acoustically diversifying an inconspicuous,
quiet vocalization, the chimpanzee hoo. This evolutionary
process may have been favoured by the fact that signallers
and recipients share the same goal, to maintain social cohesion,
particularly among those who regularly cooperate, suggesting
that call diversification has been favoured by the demands of
cooperative activities. %K animal communication, chimpanzee, call diversification, cooperation %J Royal Society Open Science %V 5 %N 5 %] 172066 %I Royal Society %C London %@ 2054-5703