Recruitment and monitoring behaviors by leaders predict following in wild Barbary macaques (<i>Macaca sylvanus</i>)

Abstract

Abstract. For group-living animals it is essential to maintain the cohesiveness of the group when traveling. Individuals have to make an accurate decision about where and when to move. Communication before and during the departure of the first individual may play a crucial role in synchronizing a collective movement. We hypothesized that individuals in a wild primate group use signals or cues prior to and after departure to achieve collective movements. With two observers we used all-occurrences behavior sampling of collective movements in a group of wild Barbary macaques (Macaca sylvanus) in the Middle Atlas, Morocco. The number of individuals displaying pre-departure behavior predicted the success of an initiation of a collective movement. Pauses of the first departing individual after departure enhanced following behavior and might have served as recruitment signal. However, the opposite was the case for back-glancing, which functions as a monitoring signal in other species. Because in our study frequently back-glancing individuals were also less socially integrated, back glances may better be interpreted as indicators of hesitation and insecurity. To successfully initiate a collective movement, it seemed to be sufficient for a socially integrated group member to take action when other group members signal their willingness prior to departure and to occasionally wait for the group while moving.

Tibetan Macaques with Higher Social Centrality and More Relatives Emit More Frequent Visual Communication in Collective Decision-Making

“…Social centrality significantly affected the frequency of visual signals. The study by Seltmann et al demonstrated a negative correlation between the strength of social connections and the frequency of back-glance in Barbary macaques [ 9 ]. However, in a previous study related to group movements in Tibetan macaques, we found a positive correlation between the strength of social connections and the frequency of successful initiation.…”

“…We speculate that this is because the pause signal usually occurs when foraging is over, during the group departs from the feeding site into the forest and lasts long. Back-glance is not needed to monitor or recruit when a certain number of participants are present [ 9 ].…”

“…Meanwhile, other members of a collective movement can also communicate their preferences of movement direction and time to group mates, either through local communication among neighbors only [ 7 ] or through global communication in their group [ 8 ], ultimately achieving the consistency of members’ actions [ 2 ]. Clearly, the proper use of communication behaviors plays an important role in the success of consensus decision-making and the achievement of a collective movement [ 9 ].…”

“…Primates are highly cognitive and socially complex, with individuals possessing both local knowledge of the behavior of their neighbors and information about the environment holistically, thus making the functions of communicative behavior more diverse and complex [ 14 ]. For example, male barbary macaques ( Macaca sylvanus ) recruit neighboring individuals and monitor the activities of other group members when leading group movements [ 9 ]. At the same time, in primate collective movement, other members of the group may also influence the behavior of the initiator’s behavior.…”

Social Relationships Impact Collective Decision-Making in Tibetan Macaques

“…In primate species, initiation of a group movements can be accompanied by notifying behaviors (Kummer 1968) or preliminary behaviors (Sueur and Petit 2008a) that are exhibited in the pre-departure period, directly preceeding the group movement. This recruitment process often includes visual and acoustic communication, and which can influence the recruitment success of an initiation, i.e., whether the initiator is followed and, if so, by how many group members and how quickly Seltmann et al 2016;Sperber et al 2017).…”