Abstract
Collective movements are essential for maintaining group cohesion. However, group members can have different optimal departure times, depending on individual, social and contextual factors whose relative importance remains poorly known. We, therefore, studied collective departures in four groups of red-fronted lemurs (Eulemur rufifrons) in Kirindy Forest, Madagascar, to investigate the influence of an individual's age, sex, their affiliative relationships and their proximity to other group members at the time of departure on their individual departure decision. We recorded behavioural and spatial data on individual departures during 167 group movements and conducted group scans (181–279 per group) to assess affiliative relationships. All factors influenced individual departures. Both affiliation and proximity determined a mimetic joining process in which dyads with stronger affiliative bonds departed in closer succession, and individuals followed the initiator and predecessors more quickly when they were in closer proximity at departure. While the influence of affiliation is common, the effect of inter-individual distance has rarely been considered in groups with heterogeneous social relationships. Although local rules influenced joining, the overall movement pattern was mainly determined by individual traits: juveniles took protected central positions, while females made up the van and males brought up the rear. Individual needs, expressed in the departure order, to an extent overruled the effect of affiliation. These results highlight the importance of considering individual, social and contextual factors collectively in the study of collective movements.
Highlights
Living in a group provides benefits [1,2,3,4,5], such as a reduced individual predation risk [6,7,8], reduced time spent on vigilance [9] and more efficient foraging, e.g. through information transmission [10,11,12]
Mimetism has been suggested in several species to determine the joining process of collective departures [14,15]
Affiliative mimetism has been shown to determine following in primates [17,18,19,20,21,22], ungulates [23,24,25,26] and birds [27]
Summary
Living in a group provides benefits [1,2,3,4,5], such as a reduced individual predation risk [6,7,8], reduced time spent on vigilance [9] and more efficient foraging, e.g. through information transmission [10,11,12]. Joining can be based on distance, so that individuals are more likely to join a group movement when those in closest proximity to themselves do so This mechanism has been demonstrated in fish [28], domestic geese (Anser domesticus) [29], domestic sheep (Ovis aries) [23] and anonymous human groups [30]. It has been termed ‘local mimetism’ by Ward et al [28]. We prefer the term ‘spatial mimetism’ to refer to mimetism based on physical proximity, to emphasize the spatial effect and to clarify that all kinds of mimetism, spatial mimetism, can be considered a local rule
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
