scholarly journals Prey synchronize their vigilant behaviour with other group members

2007 ◽  
Vol 274 (1615) ◽  
pp. 1287-1291 ◽  
Author(s):  
Olivier Pays ◽  
Pierre-Cyril Renaud ◽  
Patrice Loisel ◽  
Maud Petit ◽  
Jean-François Gerard ◽  
...  
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Prey Species ◽  
Group Members ◽  
The Individual ◽  
The Cost ◽  
Group Member

It is generally assumed that an individual of a prey species can benefit from an increase in the number of its group's members by reducing its own investment in vigilance. But what behaviour should group members adopt in relation to both the risk of being preyed upon and the individual investment in vigilance? Most models assume that individuals scan independently of one another. It is generally argued that it is more profitable for each group member owing to the cost that coordination of individual scans in non-overlapping bouts of vigilance would require. We studied the relationships between both individual and collective vigilance and group size in Defassa waterbuck, Kobus ellipsiprymnus defassa , in a population living under a predation risk. Our results confirmed that the proportion of time an individual spent in vigilance decreased with group size. However, the time during which at least one individual in the group scanned the environment (collective vigilance) increased. Analyses showed that individuals neither coordinated their scanning in an asynchronous way nor scanned independently of one another. On the contrary, scanning and non-scanning bouts were synchronized between group members, producing waves of collective vigilance. We claim that these waves are triggered by allelomimetic effects i.e. they are a phenomenon produced by an individual copying its neighbour's behaviour.

scholarly journals Fight tactics in wood ants: individuals in smaller groups fight harder but die faster

2011 ◽  
Vol 278 (1722) ◽  
pp. 3243-3250 ◽  
Author(s):  
Tim P. Batchelor ◽  
Mark Briffa
Keyword(s):  
Group Size ◽  
Negative Influence ◽  
Resource Holding Potential ◽  
Attrition Rates ◽  
Formica Rufa ◽  
Wood Ants ◽  
Social Animals ◽  
Group Members ◽  
Per Capita ◽  
The Individual

When social animals engage in inter-group contests, the outcome is determined by group sizes and individual masses, which together determine group resource-holding potential (‘group RHP’). Individuals that perceive themselves as being in a group with high RHP may receive a motivational increase and increase their aggression levels. Alternatively, individuals in lower RHP groups may increase their aggression levels in an attempt to overcome the RHP deficit. We investigate how ‘group RHP’ influences agonistic tactics in red wood ants Formica rufa . Larger groups had higher total agonistic indices, but per capita agonistic indices were highest in the smallest groups, indicating that individuals in smaller groups fought harder. Agonistic indices were influenced by relative mean mass, focal group size, opponent group size and opponent group agonistic index. Focal group attrition rates decreased as focal group relative agonistic indices increased and there was a strong negative influence of relative mean mass. The highest focal attrition rates were received when opponent groups were numerically large and composed of large individuals. Thus, fight tactics in F. rufa seem to vary with both aspects of group RHP, group size and the individual attributes of group members, indicating that information on these are available to fighting ants.

scholarly journals Measuring Dynamical Interdependence in Small-Group Collaborations

2021 ◽  
Vol 8 (1) ◽  
pp. 95-112
Author(s):  
Peter Halpin
Keyword(s):  
Small Group ◽  
Reliability And Validity ◽  
Mathematics Assessment ◽  
Network Structures ◽  
Individual Group ◽  
Online Chat ◽  
Dynamical Network ◽  
Group Members ◽  
The Individual ◽  
Group Member

This paper addresses dynamical interdependence among the actions of group members. I assume that the actions of each member can be represented as nodes of a dynamical network and then collect the nodes into disjoint subsets (components) representing the individual group members. Interdependence among group members’ actions can then be defined with reference to a K-partite network, in which the partitions correspond to the group member components. Independence among group members’ actions can be defined with reference to a network in which the group member components are disconnected from one another. The degree to which the interactions of actual groups correspond to either of these theoretical network structures can be characterized using modified versions of existing network statistics. Taking this approach, I propose a number of network-based measures of dynamical interdependence, discuss the interpretation of the proposed measures, and consider how to assess their reliability and validity. These ideas are illustrated using an example in which dyads collaborated via online chat to complete a grade 12 level mathematics assessment.

scholarly journals Monkey see, monkey feel? Marmoset reactions towards conspecifics' arousal

2021 ◽  
Vol 8 (10) ◽  
Author(s):  
Francisco Edvaldo de Oliveira Terceiro ◽  
Erik P. Willems ◽  
Arrilton Araújo ◽  
Judith M. Burkart
Keyword(s):  
Prairie Vole ◽  
Contagion Effect ◽  
Group Members ◽  
The Individual ◽  
Group Member ◽  
Marmoset Monkeys ◽  
Three Components

Consolation has been observed in several species, including marmoset monkeys, but it is often unclear to what extent they are empathy-based. Marmosets perform well in at least two of three components of empathy-based consolation, namely understanding others and prosociality, but it is unknown to what extent they show matching with others. We, therefore, tested whether non-aroused individuals would become aroused themselves when encountering an aroused group member (indicated by piloerection of the tail). We found a robust contagion effect: group members were more likely to show piloerection themselves after having encountered an aroused versus relaxed conspecific. Moreover, group members offered consolation behaviours (affiliative approaches) towards the aroused fellow group members rather than the latter requesting it. Importantly, this pattern was shown by both aroused and non-aroused individuals, which suggests that they did not do this to reduce their own arousal but rather to console the individual in distress. We conclude that marmosets have all three components of empathy-based consolation. These results are in line with observations in another cooperative breeder, the prairie vole.

scholarly journals The group size effect and synchronization of vigilance in the Tibetan wild ass

2020 ◽  
Author(s):  
Xinxin Wang ◽  
Le Yang ◽  
Yumeng Zhao ◽  
Cong Yu ◽  
Zhongqiu Li
Keyword(s):  
Size Effect ◽  
Group Size ◽  
Nature Reserve ◽  
Prey Species ◽  
The Other ◽  
Effective Strategy ◽  
Positive Correlation ◽  
Group Size Effect ◽  
Wild Ass ◽  
Group Members

Abstract Vigilance behavior is considered as an effective strategy for prey species to detect predators. An individual benefits from living in a group by reducing the time spent being vigilant without affecting the probability of detecting a predator. However, the mechanism producing a decrease in vigilance with increasing group size is unclear. Many models of vigilance assume that group members scan independently of one another. Yet in recent studies, the other 2 patterns of vigilance, coordination and synchronization, were reported in some species. In 2 summers (2018 and 2019), we studied the group-size effect on vigilance and foraging of Tibetan wild ass in Chang Tang Nature Reserve of Tibet. We also tested whether individuals scan the environment independently, tend to coordinate their scans, or tend to synchronize their vigilance. The results showed that individuals decreased the time spent on vigilance with increasing group size, while increased the time spent foraging. Group members scanned the environment at the same time more frequently and there was a positive correlation between group members’ behaviors, indicating that Tibetan wild asses tend to synchronize their vigilance.

scholarly journals Individual willingness to leave a safe refuge and the trade-off between food and safety: a test with social fish

2019 ◽  
Vol 286 (1907) ◽  
pp. 20190826 ◽  
Author(s):  
Jesse Balaban-Feld ◽  
William A. Mitchell ◽  
Burt P. Kotler ◽  
Sundararaj Vijayan ◽  
Lotan T. Tov Elem ◽  
...  
Keyword(s):  
Predation Risk ◽  
Foraging Behaviour ◽  
Foraging Success ◽  
Group Foraging ◽  
Refuge Use ◽  
Trade Off ◽  
Individual Fish ◽  
Risk Of Predation ◽  
Group Members ◽  
The Individual

Refuges offer prey animals protection from predation, but increased time spent hiding can reduce foraging opportunities. Within social groups, individuals vary in their refuge use and willingness to forage in the presence of a predator. Here, we examine the relative foraging benefits and mortality costs associated with individual refuge use and foraging behaviour within groups of goldfish ( Carassius auratus ) under predation risk from an avian predator (little egret— Egretta garzetta ). We assessed individual order of emergence from the refuge and participation over 15 group foraging outings, and assigned each fish a daily outing index score. The individual fish that emerged from the refuge earlier than the other group members and that participated in more outings received high outing index scores and consumed more food compared with fish that tended to emerge in posterior positions and participate in fewer outings. However, individual fish that attained high outing index scores suffered a higher risk of predation. Furthermore, the amount of time the egret spent at the pool affected group foraging behaviour: as predation risk increased, groups of fish consumed significantly less food. Our results exemplify the trade-off between foraging success and safety from predation that prey species regularly experience.

Individual Contributions To Cooperative Behaviour in the Acorn Woodpecker: Effects of Reproductive Status, Sex, and Group Size

Behaviour ◽  
1985 ◽  
Vol 95 (3-4) ◽  
pp. 290-312 ◽  
Author(s):  
Ronald L. Mumme ◽  
Alan De Queiroz
Keyword(s):  
Group Size ◽  
Common Interest ◽  
Cooperative Behaviour ◽  
Individual Fitness ◽  
Strong Positive Relationship ◽  
Individual Contributions ◽  
Melanerpes Formicivorus ◽  
Group Members ◽  
Acorn Woodpeckers ◽  
The Individual

AbstractAcorn woodpeckers (Melanerpes formicivorus) are communal breeders that live in permanently territorial family groups of 2-15 individuals. All group members participate in several forms of cooperative behaviour, which we define as the investment of resources in a common interest shared by other group members (CHASE, 1980). Acorn woodpecker group interests include the caching of acorns in a specialized storage tree (the granary), maintenance of the granary, and defence of the granary against intra- and interspecific intruders. Because of a strong positive relationship between the availability of stored acorns and group reproductive success, investments in acorn storage, granary maintenance, and granary defence have a direct positive effect on the individual fitness of breeders. Non-breeding helpers, however, do not realize a direct reproductive reward, and therefore profit less directly from investment in these forms of cooperative behaviour. Thus, we predicted that breeders should invest more heavily in cooperative behaviour than should helpers. The prediction was upheld: for nearly every form of cooperative behaviour examined, breeders contribute significantly more than do helpers. On the other hand, while established breeders only rarely intrude on neighbouring territories, nonreproductive helpers frequently do so. These dispersal "forays" constitute attempts by helpers to locate ecologically restricted breeding vacancies. The effect that group size has on individual contributions to cooperative behaviour is unclear. Individual rates of acorn storage decrease significantly with increasing group size, but granary attendance and granary maintenance do not. Male and female acorn woodpeckers do not differ in their contributions to acorn storage, granary maintenance, or interspecific defence. Females, however, play a significantly greater role in intraspecific defence because of a female-biased intruder sex ratio and sex-specific defensive behaviour.

Why is group size correlated with the size of the host sea anemone in the false clown anemonefish?

2005 ◽  
Vol 83 (2) ◽  
pp. 372-376 ◽  
Author(s):  
Jeremy S Mitchell ◽  
Lawrence M Dill
Keyword(s):  
Group Size ◽  
Patch Size ◽  
Resource Limitation ◽  
Direct Consequence ◽  
Sea Anemone ◽  
Dominant Group ◽  
Subordinate Group ◽  
Indirect Consequence ◽  
Group Members ◽  
Group Member

When social groups monopolize discrete habitat patches, group size may be positively correlated with patch size. The correlation can be a direct consequence of limited resources. Alternatively, it can be an indirect consequence of patch-size effects on a dominant group member. We asked which of these two mechanisms was responsible for a positive correlation between the group size of false clown anemonefish (Amphiprion ocellaris Cuvier in Cuvier and Valenciennes, 1830) and that of the host sea anemone Stichodactyla gigantea (Forskål, 1775). We argue that some false clown anemonefish groups may have reached the carrying capacities of their hosts, but that the group size : patch size correlation in the population as a whole is best interpreted as an indirect consequence of a positive relationship between anemone size and the length of the dominant group member. The dominant's length in turn limits group size because dominant group members inhibit the growth of their subordinates. Thus, a correlation between group size and patch size need not imply resource limitation of subordinate group members.

scholarly journals Strategic Self-Regulation in Groups: Collective Implementation Intentions Help Cooperate When Cooperation Is Called for

2020 ◽  
Vol 11 ◽  
Author(s):  
J. Lukas Thürmer ◽  
Frank Wieber ◽  
Peter M. Gollwitzer
Keyword(s):  
Implementation Intentions ◽  
Self Regulation ◽  
Social Dilemmas ◽  
Investment Game ◽  
Prisoners Dilemma ◽  
Group Members ◽  
The Individual ◽  
Group Member

Groups need contributions that are personally costly to their members. Such cooperation is only adaptive when others cooperate as well, as unconditional cooperation may incur high costs to the individual. We argue that individuals can use We-if-then plans (collective implementation intentions, cIIs) to regulate their group-directed behavior strategically, helping them to cooperate selectively with group members in the situation planned for. In line with this prediction, a cII to consider group earnings increased cooperative decisions in a prisoners’ dilemma game when playing against another group member but not when playing against a stranger (i.e., non-group member). Moreover, cIIs to cooperate in the prisoners’ dilemma game did not increase cooperation in a structurally similar investment game that participants had not planned for. We discuss the role of collective planning in solving social dilemmas.

scholarly journals Red deer Cervus elaphus blink more in larger groups

2020 ◽  
Author(s):  
Zeke W. Rowe ◽  
Joseph H. Robins ◽  
Sean A. Rands
Keyword(s):  
Group Size ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Group Living ◽  
Blink Rate ◽  
Non Invasive ◽  
Group Members ◽  
The Individual ◽  
Perceived Predation Risk ◽  
Meaningful Measure

ABSTRACTMost animals need to spend time being vigilant for predators, at the expense of other activities such as foraging. Group-living animals can benefit from the shared vigilance effort of other group members, with individuals reducing personal vigilance effort as group size increases. Behaviours like active scanning or head lifting are usually used to quantify vigilance, but may not be accurate measures as the individual could be conducting them for other purposes. We suggest that measuring an animal’s blinking rate gives a meaningful measure of vigilance: increased blinking implies reduced vigilance, as the animal cannot detect predators when its eyes are closed. We demonstrate that as group size increases in red deer, individuals increase their blink rate, confirming the prediction that vigilance should decrease. Blinking is a simple non-invasive measure, and offers a useful metric for assessing the welfare of animals experiencing an increase in perceived predation risk or other stressors.

scholarly journals Male monkeys remember which group members have given alarm calls

2005 ◽  
Vol 273 (1587) ◽  
pp. 735-740 ◽  
Author(s):  
Serge A Wich ◽  
Han de Vries
Keyword(s):  
Group Size ◽  
Alarm Call ◽  
Alarm Calls ◽  
Unanswered Question ◽  
Alarm Calling ◽  
Group Members ◽  
Presbytis Thomasi ◽  
Group Member

Primates give alarm calls in response to the presence of predators. In some species, such as the Thomas langur ( Presbytis thomasi ), males only emit alarm calls if there is an audience. An unanswered question is whether the audience's behaviour influences how long the male will continue his alarm calling. We tested three hypotheses that might explain the alarm calling duration of male Thomas langurs: the fatigue , group size and group member behaviour hypotheses. Fatigue and group size did not influence male alarm calling duration. We found that males only ceased calling shortly after all individuals in his group had given at least one alarm call. This shows that males keep track of and thus remember which group members have called.

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