The role of neighbour proximity and context on meerkat close call acoustic structure

In many animal species, including humans, producer arousal state is
considered a key modifier of vocal production and structure. Encoding of
affective arousal state in vocalisations provides a rapid means of
information transfer about an individual’s internal state, potentially
reflecting its response to external stimuli. Meerkats, Suricata suricatta,
are a highly vocal species. They use close calls to maintain group
cohesion while foraging. Due to their patchily distributed prey,
motivation for neighbour proximity varies; being too close results in
competition (increased arousal - aggression), while too far results in
risks of losing the group and predation threats (increased arousal -
fear). We investigated how neighbour proximity, and also behavioural,
social and environmental context, influence the acoustic structure of wild
wild meerkats’ close calls. We found little effect of neighbour distance
on the majority of the acoustic parameters measured. However, there was a
consistent effect of the behavioural context in which the call was given
across several acoustic parameters. Additionally, if the nearest neighbour
was a pup calls became longer, lower and quieter. Overall, meerkat close
calls potentially convey information on current behaviour and are modified
in relation to social context. This highlights a potential mechanism in
the diversification of acoustic signals.