Moving calls: a vocal mechanism underlying quorum decisions in cohesive groups

Abstract

Members of social groups need to coordinate their behaviour when choosing between alternative activities. Consensus decisions enable group members to maintain group cohesion and one way to reach consensus is to rely on quorums. A quorum response is where the probability of an activity change sharply increases with the number of individuals supporting the new activity. Here, we investigated how meerkats (Suricata suricatta) use vocalizations in the context of movement decisions. Moving calls emitted by meerkats increased the speed of the group, with a sharp increase in the probability of changing foraging patch when the number of group members joining the chorus increased from two up to three. These calls had no apparent effect on the group's movement direction. When dominant individuals were involved in the chorus, the group's reaction was not stronger than when only subordinates called. Groups only increased speed in response to playbacks of moving calls from one individual when other group members emitted moving calls as well. The voting mechanism linked to a quorum probably allows meerkat groups to change foraging patches cohesively with increased speed. Such vocal coordination may reflect an aggregation rule linking individual assessment of foraging patch quality to group travel route.

A common rule for decision making in animal collectives across species

“…Interestingly, many previous approaches derive from the form P x = f ðxÞ=ðf ðxÞ + f ðyÞÞ (21,22,27,28), which is also a particular case of P x = f ðx; yÞ=ðf ðx; yÞ + f ðy; xÞÞ, and therefore compatible with probability matching. In other cases, the basic form P x = f ðxÞ=ðf ðxÞ + f ðyÞÞ has been modified by adding constant terms (29,30) or an extra function (25), as P x = f ðxÞ=ðf ðxÞ + f ðkÞÞ, with k a constant when animals have access to a single choice (31,32,34). Weber behavior can also be seen as a particular case.…”

Ants work harder during consensus decision-making in small groups

“…This voting behaviour is exemplified by the waggle-dance of honeybees [10], but includes chemical trails [20], vocalizations [21], posturing [5] and a range of other means [22][23][24]. These votes are mimetically reinforced by other group members or countered by votes for alternative options, though eventually one option emerges as the one favoured by the majority.…”

The Effect of Infant Body Mass on Carrier Travel Speed in Cotton-top Tamarins (Saguinus oedipus)

“…This behavior occurs also in callitrichids (Menzel and Beck 2000). Cooperative-breeding meerkats (Suricata suricatta), which also share infant care and antipredator behaviors, coordinate group speed among individuals by a vocal voting mechanism that allows cohesive travel (Bousquet et al 2011). Thus, in cooperative breeders, the reduced speed of the carriers may also affect other group members.…”