Flexible use of contact calls in a species with high fission–fusion dynamics

Abstract

The ‘social complexity hypothesis' posits that complex social systems (which entail high uncertainty) require complex communicative systems (with high vocal flexibility). In species with fission–fusion dynamics, where the fluid composition of temporary subgroups increases the uncertainty with which group members must manage their social relationships, vocal communication must be particularly flexible. This study assessed whether contact call rates vary with caller and audience characteristics in free-living spider monkeys, as well as with fission and fusion events. Adult females and immature individuals called more when in small audience settings, while audience size did not influence adult males. Adults called more when in the presence of the opposite sex, whereas immatures vocalized more in subgroups composed only by females. Females also called more when with their mature sons. We found higher call rates in periods during which fission and fusion events took place than in periods with more stable compositions and when the composition after a fission or fusion event changed from one sex to two sexes. A flexible use of contact calls allows individuals to identify themselves when they join others, particularly if they are members of the opposite sex. This socio-spatial cohesion function reduces the uncertainty about subgroup composition. This article is part of the theme issue ‘Cognition, communication and social bonds in primates’.

Call combination production is linked to the social environment in Western Australian magpies ( Gymnorhina tibicen dorsalis )

“…Indeed, we found that social factors appear to be influencing juveniles during an early stage of vocal development: call combination production varies with the number of other juvenile group members, in addition to the group adult sex ratio. Other studies have found that social interactions with conspecifics can influence vocal development [41,[81][82][83], and our study provides evidence to suggest this is the case for call combination production in magpies. Interestingly, our results suggest that group size does not affect juvenile callers in the same way it does adult callers: group size does not correlate with variation in juvenile call combination frequency or diversity.…”

Social factors drive vocal exchanges in red-capped mangabeys (Cercocebus torquatus)

“…Several functions, all related to socio-spatial coordination within a group and not mutually exclusive, have been proposed. For some authors, these calls would have a determinant role in the initiation and/or regulation of group movements (Neumann and Zuberbühler, 2016;Sperber et al, 2017), in the coordination of subgroup fusions (Briseño-Jaramillo et al, 2022), or would allow for maintained contact between isolated or distant individuals by giving spatial indications (Digweed et al, 2007;Snowdon and Hodun, 1981).…”

Variation in communicative complexity in relation to social structure and organization in non-human primates

“…Spider monkeys exchange a variety of signals, including facial expressions, short-lasting contacts, long-lasting contacts and vocalizations [49–51]; for a detailed treatment of vocalizations see [52]. In many primate species, grooming is an affiliative signal [53], reflecting the value and compatibility of social relationships [15].…”