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Author Fischhoff, I.R.; Sundaresan, S.R.; Cordingley, J.; Larkin, H.M.; Sellier, M.-J.; Rubenstein, D.I. url  doi
openurl 
  Title Social relationships and reproductive state influence leadership roles in movements of plains zebra, Equus burchellii Type Journal Article
  Year 2007 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 73 Issue 5 Pages 825-831  
  Keywords collective movements; drinking; equid; Equus burchellii; foraging; group dynamics; motivation; plains zebra; reproductive status; social relationships  
  Abstract In animal groups, collective movements emerge from individual interactions. Biologists seek to identify how characteristics of actors in these groups, and their relationships, influence the decision-making process. We distinguished two basic factors determining leadership in group choices: identity and state. We hypothesized that identity is more important to leadership in groups with stable relationships, which permit the development of habitual roles. In groups with fluid membership, particular individuals or subgroups are less likely to emerge as consistent leaders. Instead, we predicted that movement initiation in unstable groups depends on individual state at the time of the decision. We characterized how identity and reproductive state influenced leadership patterns in the movements of plains zebra. As in many other mammals, lactation in this species significantly alters water and energy needs. We investigated leadership in tightly knit harems and loosely bonded herds of multiple harems. Harem females tended to have habitual roles in the initiation of harem movement. In herds, however, we found no consistent leaders among harems. At both levels of social organization, lactation was a key determinant of leadership. In harems, lactating females were more likely to initiate movement than nonlactating females. In turn, harems containing lactating females were more likely to lead herd movements. Thus, we conclude that social relationships and reproductive state together shape the interactions that produce group behaviours. One benefit to lactating females of leading herd movements is preferential access to scarce water. Thus, leadership roles in group decisions may have fitness consequences.  
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  Call Number Equine Behaviour @ team @ room B 3.092 Serial (up) 1825  
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Author Meunier, H.; Leca, J.B.; Deneubourg, J.L.; Petit, O. doi  openurl
  Title Group movement decisions in capuchin monkeys: the utility of an experimental study and a mathematical model to explore the relationship between individual and collective behaviours Type Journal Article
  Year 2006 Publication Behaviour Abbreviated Journal Behaviour  
  Volume 143 Issue Pages 1511-1527  
  Keywords animal society – collective decision-making – primates – group movement – mathematical modeling  
  Abstract In primate groups, collective movements are typically described as processes dependent on leadership mechanisms. However, in some species, decision-making includes negotiations and distributed leadership. These facts suggest that simple underlying processes may explain certain decision mechanisms during collective movements. To study such processes, we have designed experiments on white-faced capuchin monkeys (Cebus capucinus) during which we provoked collective movements involving a binary choice. These experiments enabled us to analyse the spatial decisions of individuals in the group. We found that the underlying process includes anonymous mimetism, which means that each individual may influence all members of the group. To support this result, we created a mathematical model issued from our experimental data. A totally anonymous model does not fit perfectly with our experimental distribution. A more individualised model, which takes into account the specific behaviour of social peripheral individuals, revealed the validity of the mimetism hypothesis. Even though white-faced capuchins have complex cognitive abilities, a coexistence of anonymous and social mechanisms appears to influence their choice of direction during collective movements. The present approach may offer vital insights into the relationships between individual behaviours and their emergent collective acts.  
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  Notes Approved no  
  Call Number Serial (up) 2066  
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Author Conradt, L.; Roper, T.J. url  doi
openurl 
  Title Deciding group movements: Where and when to go Type Journal Article
  Year 2010 Publication Behavioural Processes Abbreviated Journal Behav. Process.  
  Volume 84 Issue 3 Pages 675-677  
  Keywords activity synchronisation; aggregation rules; collective decisions; democracy; group decisions; sexual segregation; decision sharing; social choice theory  
  Abstract A group of animals can only move cohesively, if group members “somehow” reach a consensus about the timing (e.g., start) and the spatial direction/destination of the collective movement. Timing and spatial decisions usually differ with respect to the continuity of their cost/benefit distribution in such a way that, in principle, compromises are much more feasible in timing decision (e.g. median preferred time) than they are in spatial decisions. The consequence is that consensus costs connected to collective timing decisions are usually less skewed amongst group members than are consensus costs connected to spatial decisions. This, in turn, influences the evolution of decision sharing: sharing in timing decisions is most likely to evolve when conflicts are high relative to group cohesion benefits, while sharing in spatial decisions is most likely to evolve in the opposite situation. We discuss the implications of these differences for the study of collective movement decisions.  
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  ISSN 0376-6357 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial (up) 5086  
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Author Pillot, M.-H.; Deneubourg, J.-L. url  doi
openurl 
  Title Collective movements, initiation and stops: Diversity of situations and law of parsimony Type Journal Article
  Year 2010 Publication Behavioural Processes Abbreviated Journal Behav. Process.  
  Volume 84 Issue 3 Pages 657-661  
  Keywords Collective movement; Decision-making; Sheep  
  Abstract The environment of animals is often heterogeneous, containing zones that may be dedicated specifically to resting, drinking or feeding. These functional zones may spread over a more or a less extensive area. Thus, mobile animals may have to move from one patch to another when resources are locally depleted or when they need to change activity. The mechanisms involved in collective movement appear simple at first glance, but a brief reflection shows the real difficulty of the problem in terms of the numerous environmental, physical, physiological and social parameters involved. This review is mainly concerned with collective movements, which are characterised by a directional and temporal coordination, where individuals mutually influence each other, meaning this coordination mainly depends on social interactions ([Huth and Wissel, 1992], [Warburton and Lazarus, 1991], [Couzin and Krause, 2003] and [Couzin et al., 2002]). In literature, two types of movement are discussed: large-scale movement and small-scale movement. First, we define these types of movement and then discuss the behavioural mechanisms involved. Secondly, we show that short and long movement but also moving and stopping may result from the outcome of parameters modulation underpinning collective decision-making.  
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  ISSN 0376-6357 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial (up) 5088  
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Author Sueur, C.; Petit, O. url  doi
openurl 
  Title Signals use by leaders in Macaca tonkeana and Macaca mulatta: group-mate recruitment and behaviour monitoring Type Journal Article
  Year 2010 Publication Animal Cognition Abbreviated Journal Anim. Cogn.  
  Volume 13 Issue 2 Pages 239-248  
  Keywords Decision-making – Collective movement – Intention – Macaque – Social style – Kinship  
  Abstract Abstract  Animals living in groups have to make consensus decisions and communicate with each other about the time, or the direction, in which to move. In some species, the process relies on the proposition of a single individual, i.e. a first individual suggests a movement and the other group members decide whether or not to join this individual. In Tonkean (Macaca tonkeana) and rhesus macaques (Macaca mulatta), it has been observed that this first individual displays specific signals at departure. In this paper, we aimed to explore the function of such behaviours, i.e. if these behaviours were recruitment signals or only cues about the motivation of the first departed individual. We carried out temporal analyses and studied the latencies of the first departed individual’s behaviours and of the joining of other group members. We also assessed whether the social style of a species in terms of dominance and kinship relationships influenced the patterns of signal emissions. We then analyzed how the first departed individual decided to make a pause or to stop it according to the identities of group members that joined the collective movement. Results showed that Tonkean macaques and rhesus macaques seemed to use back-glances to monitor the joining of other group members and pauses to recruit such individuals. This was especially the case for highly socially affiliated individuals in Tonkean macaques and kin-related individuals in rhesus macaques. Moreover, back-glances and pauses disappeared when such individuals joined the first departed individual. From these results, we suggested that such behaviour could be considered intentional. Such findings could not be highlighted without temporal analyses and accurate observations on primate groups in semi-free ranging conditions.  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial (up) 5117  
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Author Conradt, L.; Krause, J.; Couzin, I. D.; Roper, T. J. url  doi
openurl 
  Title “Leading According to Need” in Self-Organizing Groups Type Journal Article
  Year 2009 Publication The American Naturalist Abbreviated Journal Am Nat  
  Volume 173 Issue 3 Pages 304-312  
  Keywords behavioral synchrony, collective group decisions, democracy and egalitarianism in animals, public goods experiments, sexual segregation, social choice theory  
  Abstract Self‐organizing‐system approaches have shed significant light on the mechanisms underlying synchronized movements by large groups of animals, such as shoals of fish, flocks of birds, or herds of ungulates. However, these approaches rarely consider conflicts of interest between group members, although there is reason to suppose that such conflicts are commonplace. Here, we demonstrate that, where conflicts exist, individual members of self‐organizing groups can, in principle, increase their influence on group movement destination by strategically changing simple behavioral parameters (namely, movement speed, assertiveness, and social attraction range). However, they do so at the expense of an increased risk of group fragmentation and a decrease in movement efficiency. We argue that the resulting trade‐offs faced by each group member render it likely that group movements are led by those members for which reaching a particular destination is most crucial or group cohesion is least important. We term this phenomenon leading according to “need” or “social indifference,” respectively. Both kinds of leading can occur in the absence of knowledge of or communication about the needs of other group members and without the assumption of altruistic cooperation. We discuss our findings in the light of observations on fish and other vertebrates.  
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  Call Number Equine Behaviour @ team @ Serial (up) 5121  
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Author Dyer, J.R.G.; Johansson, A.; Helbing, D.; Couzin, I.D.; Krause, J. url  doi
openurl 
  Title Leadership, consensus decision making and collective behaviour in humans Type Journal Article
  Year 2009 Publication Philosophical Transactions of the Royal Society B: Biological Sciences Abbreviated Journal Phil. Trans. Biol. Sci.  
  Volume 364 Issue 1518 Pages 781-789  
  Keywords * leadership * consensus decision making * collective behaviour * human group  
  Abstract This paper reviews the literature on leadership in vertebrate groups, including recent work on human groups, before presenting the results of three new experiments looking at leadership and decision making in small and large human groups. In experiment 1, we find that both group size and the presence of uninformed individuals can affect the speed with which small human groups (eight people) decide between two opposing directional preferences and the likelihood of the group splitting. In experiment 2, we show that the spatial positioning of informed individuals within small human groups (10 people) can affect the speed and accuracy of group motion. We find that having a mixture of leaders positioned in the centre and on the edge of a group increases the speed and accuracy with which the group reaches their target. In experiment 3, we use large human crowds (100 and 200 people) to demonstrate that the trends observed from earlier work using small human groups can be applied to larger crowds. We find that only a small minority of informed individuals is needed to guide a large uninformed group. These studies build upon important theoretical and empirical work on leadership and decision making in animal groups.  
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  Call Number Equine Behaviour @ team @ Serial (up) 5122  
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Author Sueur, C.; Petit, O. url  doi
openurl 
  Title Shared or unshared consensus decision in macaques? Type Journal Article
  Year 2008 Publication Behavioural Processes Abbreviated Journal Behav. Process.  
  Volume 78 Issue 1 Pages 84-92  
  Keywords Collective movement; Decision-making; Leadership; Social style  
  Abstract Members of a social group have to make collective decisions in order to synchronise their activities. In a shared consensus decision, all group members can take part in the decision whereas in an unshared consensus decision, one individual, usually a dominant member of the group, takes the decision for the rest of the group. It has been suggested that the type of decision-making of a species could be influenced by its social style. To investigate this further, we studied collective movements in two species with opposed social systems, the Tonkean macaque (Macaca tonkeana) and the rhesus macaque (Macaca mulatta). From our results, it appears that the decision to move is the result of the choices and actions of several individuals in both groups. However, this consensus decision involved nearly all group members in Tonkean macaques whereas dominant and old individuals took a prominent role in rhesus macaques. Thus, we suggest that Tonkean macaques display equally shared consensus decisions to move, whereas in the same context rhesus macaque exhibit partially shared consensus decisions. Such a difference in making a collective decision might be linked to the different social systems of the two studied species.  
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  ISSN 0376-6357 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial (up) 5129  
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Author Stueckle, S.; Zinner, D. url  doi
openurl 
  Title To follow or not to follow: decision making and leadership during the morning departure in chacma baboons Type Journal Article
  Year 2008 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 75 Issue 6 Pages 1995-2004  
  Keywords chacma baboon; collective movement; consensus; decision making; leadership; Papio hamadryas ursinus  
  Abstract To benefit from group living, group members need to keep the group cohesive by coordinating time and direction of travelling. Self-organization and leadership are two means of coordination and two types of decision can be made on the group level: combined and consensus. We studied the initiation process of group movements during the morning departure of a group of chacma baboons, Papio hamadryas ursinus, from its sleeping site in De Hoop Nature Reserve, South Africa. Findings from other female-bonded primate groups led us to hypothesize that females should play a major role in the decision-making process. Approximately 75% of the adults made a start attempt, with 62 of 92 attempts being by males. There was no sex difference in the probability of being successful when initiating an attempt. Lactating females initiated fewer than pregnant or cycling females. Thus, at least for this group of chacma baboons, leadership appeared to be distributed and the decision about the timing of departure and travel direction seemed to be a partially shared consensus decision with adult males contributing more to the decision outcome, with a slightly more prominent role of the dominant male. Our results do not support the [`]leading females' hypothesis. No behavioural patterns that might serve as specialized signals leading to a more successful recruitment of other group members were observed. The departure process appeared to be coordinated merely through individuals setting an example by moving off.  
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  Series Volume Series Issue Edition  
  ISSN 0003-3472 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial (up) 5130  
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Author Faria, J.J.; Dyer, J.R.G.; Tosh, C.R.; Krause, J. url  doi
openurl 
  Title Leadership and social information use in human crowds Type Journal Article
  Year 2010 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 79 Issue 4 Pages 895-901  
  Keywords collective animal behaviour; group; human; inadvertent social cue; information; leadership  
  Abstract One of the big challenges for group-living animals is to find out who in a group has pertinent information (regarding food or predators) at any moment in time, because informed individuals may not be obviously recognizable to other group members. We found that individuals in human groups were capable of identifying those with information, and this identification increased group performance: the speed and accuracy of groups in reaching a target. Using video analysis we found how informed individuals might have been identified by other group members by means of inadvertent social cues (such as starting order, time spent following and group position). Furthermore, we were able to show that at least one of these cues, the group position of informed individuals, was indeed correlated with group performance. Our final experiment confirmed that leadership was even more efficient when the group members were given the identity of the leader. We discuss the effect of information status regarding the presence and identity of leaders on collective animal behaviour.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-3472 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial (up) 5192  
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