Effect of valuable relationship on reconciliation and initiator of reconciliation in captive bottlenose dolphins (<Emphasis Type="Italic">Tursiops truncatus</Emphasis>)

Reconciliation, post-conflict affiliation between former opponents, was suggested to repair the relationship between former opponents. The number of times that each former opponent initiates reconciliation may be affected by the dominance style. Despotic dominance style was suggested to restrain the initiation of reconciliation by recipients of aggression, unlike relaxed dominance style. Although reconciliation was suggested to restore relationships, reconciliation sometimes did not occur. The valuable relationship hypothesis predicts that reconciliation is more likely to occur when former opponents share a valuable relationship. However, few studies have tested this hypothesis in non-primate species. This study investigated, in captive bottlenose dolphins, which are suggested as having a relaxed dominance style, whether aggressors or recipients of aggression initiate reconciliation, and whether relationships between former opponents affect the occurrence of reconciliation. The number of times that aggressors or recipients of aggression initiate reconciliation did not differ. Recipients of aggression initiated reconciliation sooner than aggressors. These results support the prospect that recipients of aggression are not impeded in initiating reconciliation in relaxed species. Former opponents who share a more affiliative relationship were reconciled more frequently. Bottlenose dolphins were suggested to receive the benefits from individuals who shared more affiliative relationships. The valuable relationship hypothesis may be supported in bottlenose dolphins.     

Ravens reconcile after aggressive conflicts with valuable partners

Reconciliation, a post-conflict affiliative interaction between former opponents, is an important mechanism for reducing the costs of aggressive conflict in primates and some other mammals as it may repair the opponents' relationship and reduce post-conflict distress. Opponents who share a valuable relationship are expected to be more likely to reconcile as for such partners the benefits of relationship repair should outweigh the risk of renewed aggression. In birds, however, post-conflict behavior has thus far been marked by an apparent absence of reconciliation, suggested to result either from differing avian and mammalian strategies or because birds may not share valuable relationships with partners with whom they engage in aggressive conflict. Here, we demonstrate the occurrence of reconciliation in a group of captive subadult ravens (Corvus corax) and show that it is more likely to occur after conflicts between partners who share a valuable relationship. Furthermore, former opponents were less likely to engage in renewed aggression following reconciliation, suggesting that reconciliation repairs damage caused to their relationship by the preceding conflict. Our findings suggest not only that primate-like valuable relationships exist outside the pair bond in birds, but that such partners may employ the same mechanisms in birds as in primates to ensure that the benefits afforded by their relationships are maintained even when conflicts of interest escalate into aggression. These results provide further support for a convergent evolution of social strategies in avian and mammalian species.     

Resolution of aggressive conflicts by immature long-tailed macaques Macaca fascicularis

The behaviour following aggressive interactions differed from the behaviour following friendly or neutral control interactions among unrelated immature male Macaca fascicularis. Former opponents interacted again sooner and more often after aggression than after a friendly or neutral encounter. The higher rate did not reflect a general increase in social activity. The behaviour characterizing encounters between former opponents also differed in the two situations, with more affiliative interactions postconflict. In both situations, however, most interactions between former opponents were initiated by the higher-ranking aggressor. This pattern of interactions between former opponents is interpreted as a repair mechanism for relationships strained by aggression (i.e. reconciliation). A similar pattern of interactions was found for related animals, though it occurred more rarely than among non-kin.     

Dyadic and triadic reconciliation in pigtail macaques (Macaca nemestrina)

The tendency in primates for former antagonists to approach and affiliate following aggression has been termed reconciliation because the response is thought to resolve social conflicts produced by aggression. In primate societies, however, an aggressive interaction between two individuals often spreads to include other group members, especially the kin of the combatants. If post conflict affiliation resolves aggressive conflicts in a group, then affiliative increases might occur between combatants and the kin of their opponents following aggression as well as between former opponents. This hypothesis was tested in a captive group of 39 pigtail macaques (Macaca nemestrina) by comparing affiliative response frequencies of combatants during the 5 minute period following aggression to affiliative response frequencies during 5 minute baseline periods not preceded by aggressive activity. Following aggression, affiliation rates increased between combatants and their opponents, aggressors and the kin of their opponents, and aggressors and their own kin. Additional analyses showed that aggression among kin was reconciled more often than aggression among nonkin. Recipients of aggression reconciled with their attackers more often than aggressors reconciled with their victims. Animals with similar dominance ranks reconciled proportionately more often than those with large rank disparities and aggressive infractions of a calculated dominance hierarchy were reconciled more often than attacks consistent with the hierarchy. Results suggest that both dyadic and triadic reconciliations occur in M. nemestrina and that compared to other primate species M. nemestrina exhibit a moderate-to-high conciliatory tendency.     

Sex Differences in Reconciliation and Post-Conflict Anxiety in Bonnet Macaques

Rates of reconciliation vary widely between different types of opponents, and post‐conflict anxiety has been proposed to mediate individual variation in reconciliation rates. We investigated the form and function of reconciliation in a wild, provisioned group of bonnet macaques (Macaca radiata) with the prediction that sex differences in post‐conflict anxiety would be associated with sex differences in conciliatory tendency. Individuals in the study group had a conciliatory tendency of 29.3%. Victims avoided their former opponents at a higher rate following aggression than during matched‐control samples, and reconciliation decreased the rate of avoidance. Although victims showed a higher rate of anxiety‐related behavior than did aggressors, anxiety‐related behavior was elevated after aggression and reduced following reconciliation in both victims and aggressors. Female–female opponents showed higher rates of anxiety‐related behavior before reconciliation than they did following unreconciled aggression. In contrast, male–male and female–male opponents showed increased anxiety‐related behavior following aggression regardless of the occurrence of reconciliation. Moreover, female–female opponents had a higher conciliatory tendency than did female–male opponents. The elevated post‐conflict anxiety shown by female–female opponents before reconciliation, along with their high conciliatory tendency, suggests that post‐conflict anxiety promotes reconciliation. In sum, the sex differences in post‐conflict behavior found in this study support the hypothesis that variation in post‐conflict anxiety mediates differential rates of reconciliation.     

Methodological and Evolutionary Aspects of Reconciliation among Primates

Affinitive contact between former opponents soon after a conflict has been demonstrated in a growing number of primate species. Several recent studies show that such contact reduces the probability of future conflicts, allows the recipient of aggression to reduce its anxiety, and restores tolerance between former opponents. Hence, these contacts can be termed reconciliation. In this paper, we critically discuss common methodological problems of studying reconciliation, examine functional aspects, and evaluate the existing variation in primate reconciliation in light of predictions derived from four untested hypotheses about its evolutionary origins. We find that the occurrence of reconciliation in primates is not limited to anthropoids. Neither is it limited to species with formalized dominance relations. Reconciliation is also not a prerequisite for life in permanent social groups. Instead, several lines of evidence support the hypothesis that reconciliation serves to maintain valuable social relationships between individuals. We suggest several more specific versions of this hypothesis and discuss reconciliation between kin, mates, and alliance partners, as well as a number of open questions pertaining to the mechanisms, functions and origins of reconciliation among primates.     

The Long-Term Effects of Reconciliation in Japanese Macaques Macaca fuscata

With one exception, all previous studies of reconciliation in non-human primates (friendly reunion between former opponents) have focused on demonstrating the immediate, short-term effects despite the widely held view that reconciliation has a long-term function of repairing social relationships following aggression. To investigate this long-term function I compared mean interaction rates between opponents during the 10 d following reconciled and non-reconciled conflicts to baseline levels of interaction. Aggression rates during the 10 d after non-reconciled conflicts were significantly higher than the baseline rate, whereas after reconciled conflicts aggression was minimal. Similarly, grooming, proximity and approach rates during the 10 d after non-reconciled conflicts were significantly lower than the baseline rate whereas grooming, proximity and approach rates in the 10 d after reconciled conflicts were restored to baseline levels. These results indicate that there are consequences to not reconciling with a former opponent and highlight the fact that these may be costly in terms of increased risk of long-term aggression and reduced affiliation. The data support predictions from the Relationship-Repair Hypothesis suggesting that reconciliation functions as a mechanism for the repair of social relationships damaged by aggression.     

Postconflict Affiliation Between Former Opponents in Macaca thibetana on Mt. Huangshan, China

We describe basic patterns of postconflict affiliation between former opponents within a group of wild, provisioned Tibetan macaques Macaca thibetana on Mt. Huangshan, China. Like most primates studied to date, Tibetan macaques reconciled, i.e., overall they engaged in affiliative interaction with opponents at higher rates immediately after an aggressive conflict than at other times. Probabilities of affiliation were enhanced ≤30 s after the end of hostilities. However when we examined sex partner combinations separately, we found unequivocal evidence for reconciliation only for male-male dyads. Tolerant interaction among other partner combinations apparently was not disrupted after a conflict, presumably obviating the need to reconcile. One aspect of reconciliation among males was consistent with other indications of a despotic dominance style: aggressors initiated a higher proportion of affiliative interactions after a conflict than at other times. Another aspect of reconciliation was more typical of relaxed dominance styles: males used specialized behaviors (embraces and same-sex mounts) disproportionately to reconcile. We also found inconsistent evidence for the valuable relationship hypothesis; probabilities of reconciliation were enhanced for male-male dyads with the closest affiliative relationships, but not for those that displayed the most tolerance or mutual agonistic support. We discuss reconciliation and other aspects of conflict management among males in the context of a group with nearly even sex ratios and high male-male mating competition.     

A Statistical Modelling Approach to the Occurrence and Timing of Reconciliation in Wild Japanese Macaques

In various social species, animals have been observed to share friendly relationships with some group members and to resolve conflicts through reconciliation, the exchange of affiliative behaviour soon after a conflict that functions to restore the relationship between the former opponents. The valuable relationship hypothesis predicts that reconciliation should be observed more often after conflicts between friends. Friendly relationships can be described by three dimensions (i.e. value, security and compatibility); however, research into the relative importance of these dimensions for the occurrence of reconciliation is sparse. Moreover, reconciliation may depend on factors other than the social relationship between opponents including, for example, their social status or the context of the conflict. Our study aimed at analysing which factors are important determinants of reconciliation and at testing the valuable relationship hypothesis, by analysing the relative effects of relationship value, security and compatibility on the occurrence and timing of reconciliation. We collected data on two troops of wild Japanese macaques living on Yakushima Island, Japan, and selected the best predicting variables of reconciliation using linear mixed models. Our results show that reconciliation occurs more frequently, and earlier, after conflicts between opponents who exchange a higher percentage of grooming. Two additional variables related to relationship security and value were selected in the best models: frequency of aggression and of approaches resulting in tolerated co‐feeding. Among the variables not related to relationship quality, distance between opponents at the end of the conflict, kinship, sex of the opponents and context of conflict (i.e. during feeding or social time) were included in our models. Our findings support the valuable relationship hypothesis and, in particular, highlight that the fitness‐related benefits of social relationships (i.e. the relationship value) are important determinants of the evolution of friendly relationships and reconciliation.     

Reconciling with Valuable Partners by Long-tailed Macaques

In primates and other social mammals, opponents in aggressive conflicts have been reported to seek one another out after fights for various types of friendly interaction. In long-tailed macaques, these friendly reunions have been shown to restore aspects of the social relationship of the opponents to their preconflict state, and they have thus been interpreted as reconciliations. Although postconflict reconciliation would seem to be adaptive to gregarious animals that establish individualized social relationships, its occurrence is variable among species, groups and dyads. Some of this variation probably reflects costs and benefits of reconciling in different situations. One factor that might influence the benefit of reconciliation and hence its occurrence is the value of the social partner as a social or ecological resource: reconciliation should occur more often after fights with valuable social partners. We conducted an experiment to test this hypothesis using pairs of monkeys (Macaca fascicularis) as their own controls. First, baseline rates of reconciliation after experimenter-induced conflict were measured. Then, the value of the relationship, at least in the test context, was increased by training each pair of monkeys to perform a simple cooperative task in which each got access to food only if the partner fed nearby simultaneously. Finally, the reconciliation rate was measured again after training and compared to its baseline value. In 6 of 7 dyads, the reconciliation rate increased after training, and the median reconciliation rate after training was 3 times higher than at baseline. While the results are consistent with the value hypothesis, there are other potential explanations. Comparison of friendly behavior when there had been no prior aggression in baseline and post-training phases, however, suggested that the increase in reconciliation rate was neither the result of a general increase in compatibility nor the result of anticipated conflict in the cofeeding context.     

Reconciliation and the Costs of Aggression in Wild Barbary Macaques (Macaca sylvanus): A Test of the Integrated Hypothesis

The ‘integrated hypothesis’ predicts that reconciliation (the post‐conflict friendly interaction between former opponents observed in various group‐living species) functions to reduce anxiety and the risk of aggression from the former opponent or a bystander in the aftermath of a conflict. It also predicts that relationship quality between opponents affects the occurrence of reconciliation and modulates the anxious response of the opponents after a conflict. Because of the asymmetric nature of aggressive interactions, the cost of aggression is likely to differ between the victim and the aggressor. The aim of this study was to test the predictions of the ‘integrated hypothesis’ independently for the victim and the aggressor of a conflict. We collected data on two wild groups of Barbary macaques. This study represents, to our knowledge, the first systematic test of the integrated hypothesis on wild, non‐provisioned animals. Victims of aggression were at a greater risk of receiving aggression from the former opponent or a bystander after a conflict and showed elevated anxiety. We found no such costs for the aggressor. Reconciliation reduced anxiety in the victim but did not reduce their risk of receiving aggression. Finally, relationship quality affected the occurrence of reconciliation but did not modulate post‐conflict anxiety. The results of our study show that the costs of aggression are asymmetrically distributed between the victim and the aggressor. Such differences are likely to lead to different social tactics used by the victim and the aggressor in the aftermath of a conflict.     

Post‐conflict third‐party affiliation in chimpanzees: what's in it for the third party?

Affiliative behavior after conflicts between conflict participants and other group members is common in many primate species. The proposed functions for such triadic interactions are numerous, mostly concerning the benefit for the former conflict opponents. We investigated post‐conflict third‐party affiliation (TPA) in captive chimpanzees (Pan troglodytes) with the aim of assessing what the affiliating third parties may gain from affiliation. Specifically, we tested whether third‐party‐initiated affiliation protects the third parties from further aggression by conflict opponents. We found support for this “self‐protection hypothesis,” in that third parties selectively directed affiliation to those opponents who more often gave further aggression to them, and affiliation effectively decreased their chance of receiving aggression from these opponents. However, a subset of affiliation, provided to conflict victims by their own kin, appeared to not be self‐protective and the function of it remained open. We conclude that chimpanzee third‐party‐initiated affiliation is a more heterogeneous behavior than thus far assumed. Am. J. Primatol. 71:409–418, 2009. © 2009 Wiley‐Liss, Inc.     

Postconflict third-party affiliation in rooks, Corvus frugilegus

Conflict features in the lives of many animal species and induces social stress mediated by glucocorticoid hormones [1]. Postconflict affiliation, between former opponents (reconciliation) or between former opponents and a bystander (third-party affiliation), has been suggested as a behavioral mechanism for reducing such stress [2], but has been studied almost exclusively in primates [3]. As with many primates, several bird species live in social groups and form affiliative relationships [4]. Do these distantly related animals also use affiliative behavior to offset the costs of conflict? We studied postconflict affiliation in a captive group of rooks. Unlike polygamous primates, monogamous rooks did not reconcile with former opponents. However, we found clear evidence of third-party affiliation after conflicts. Both initiators and targets of aggression engaged in third-party affiliation with a social partner and employed a specific behavior, bill twining, during the postconflict period. Both former aggressors and uninvolved third parties initiated affiliative contacts. Despite the long history of evolutionary divergence, the pattern of third-party affiliation in rooks is strikingly similar to that observed in tolerant primate species. Furthermore, the absence of reconciliation in rooks makes sense in light of the species differences in social systems.     

Post-conflict Social Events in Wild Mountain Gorillas (Mammalia,Hominoidea). I. Social Interactions between Opponents

Researchers have documented elevated rates of affinitive interaction between opponents shortly after aggressive conflicts, or reconciliation, in many primate species. Reconciliation may ameliorate the immediate negative effects of aggression by reducing the chance of further aggression between opponents and thus reducing tension, and may avert or repair damage to long-term social relationships important to the animals' fitness. Data on post-conflict interactions between opponents in two groups of wild mountain gorillas (Gorilla gorilla beringei) fail to show reconciliation after conflicts between females, between males, or between immatures, but females seem to commonly reconcile themselves with males after receipt of male aggression. Females and subordinate males often avoid same-sex opponents after conflicts. Females commonly retaliate against female aggressors, and post-conflict rates of aggression between females are higher than baseline levels. Females may not need to achieve reconciliation with each other because relationships between co-resident relatives are resiliant, while those between non-relatives are mostly neutral to antagonistic. Males are, however, important social partners and protectors of females, and female transfer is common. Thus, the results strongly support the ‘important relationships’ hypothesis for the function of reconciliation.     

Following the rules: why small groups of tamarins do not reconcile conflicts

Reconciliation is the post-conflict friendly reunion between opponents. A series of conditions and rules in order for reconciliation to take place has been recently proposed. One critical condition is that the relationship between opponents must be disrupted. We tested this condition using post-conflict and matched-control observations on 4 small groups of tamarins (Saguinus labiatus). Our previous lack of evidence for reconciliation was confirmed. No post-conflict relationship damage was therefore expected. We found evidence that relationships were disturbed following conflicts over food but, as in other primates, no evidence for reconciliation following such conflicts was found. For non-food-related conflicts there was no evidence that relationships were disturbed, as opponents were in close proximity to each other and resumed the exact same activity as frequently in the post-conflict observations as they did in the matched-control observations. We conclude that 'everyday' aggression may not disrupt the relationships among individuals from the same family group and therefore reconciliation is not needed.     

The Function and Determinants of Reconciliation in <Emphasis Type="BoldItalic">Pan troglodytes</Emphasis>

Reconciliation (the postconflict affiliative reunion between former opponents) may mitigate costs of aggressive conflict by repairing the opponents’ relationship and reducing stress. We showed that postconflict levels of self-directed behavior were lower after reconciliation than when reconciliation did not occur in chimpanzees (Pan troglodytes) at Chester Zoo, providing support for a stress-alleviating function for reconciliation. Further, we investigated the effects of multiple factors on the occurrence of reconciliation using generalized linear mixed models. We performed 2 separate analyses, a “traditional” analysis and a “targeted” analysis. The former included variables previously used to assess the occurrence of reconciliation in primates, i.e., conflict characteristics, sex combination, and a simple measure of relationship value. The latter included species-specific variables such as the occurrence of consolation (postconflict affiliation from a bystander to the recipient of aggression); initiation of the conflict with a bluff display; and measures of relationship value, compatibility, and security specific to the study group. Whereas the traditional analysis showed that female-female dyads and valuable partners were most likely to reconcile, the targeted analysis showed that reconciliation was less likely to occur when consolation took place or when aggression was initiated with bluff displays. Further analyses revealed that the effect of sex-combination on reconciliation was due to its intercorrelation with bluff display. This study highlights the importance of considering variables specific to the study species and group when investigating the determinants of reconciliation and warns against premature interpretation of results without due consideration for all other possible determinants.     

Reconciliation in the Spotted Hyena (Crocuta crocuta)

Theory predicts that it should often be in the best interests of gregarious animals to repair social bonds damaged by within-group conflict. Indeed, reconciliation in many primates takes the form of affiliative behavior occurring shortly after a conflict. Here we inquired whether reconciliation also occurs among spotted hyenas ( Crocuta crocuta ), gregarious carnivores whose social lives share much in common with those of cercopithecine primates. In a large group of free-living hyenas in Kenya, we used focal animal observations to monitor rates at which various affiliative behaviors occurred before and after dyadic aggressive interactions. An affiliative behavior was identified as having a conciliatory function only if it occurred more frequently after than before fights, and if it was also associated with reduced rates of aggression between former opponents during the post-conflict interval. Of all affiliative behaviors monitored, only two types satisfied both these criteria: greeting behavior and non-aggressive approach. Over 72% of conciliatory behaviors occurred within the first five minutes after a fight, and hyenas reconciled after 14.6% of 698 fights. Mean conciliatory tendency (CT) for individual hyenas was 11.3%. Hyenas exhibited higher CTs when they were recipients (victims) of aggression than when they were aggressors, and they showed higher CTs in interactions with non-kin than with kin. Conciliatory tendencies did not vary with age–sex classes of opponents or with rank distance between opponents . Conciliatory tendency in spotted hyenas fell at the low end of the CT range observed among primates.     

Impaired reconciliation in rhesus macaques with a history of early weaning and disturbed socialization

An attempt had been made to create five social groups from rhesus macaques with a history of early separation from their mothers, early weaning and hand feeding and, in most cases, previous housing in single cages. We investigated the exchange of affiliative behaviours after an aggressive encounter and selective attraction to the former opponent, a phenomenon previously well described in rhesus monkeys and called reconciliation. Evidence for reconciliation was only found in one of the five groups studied (corrected conciliatory tendency=13%). This group consisted of younger animals that had, at least temporarily, been living together after separation from their mothers. In the other groups studied, containing animals with a varied background, aggressive interactions were not followed by affiliative behaviours or attraction between former opponents. Our results indicate that the use of reconciliatory behaviours in adult monkeys is dependent upon social training. Lack of functional reconciliation might be one of the explanations to the severe and uncontrolled aggression previously found in groups of rhesus macaques created from animals with disturbed early socialization.     

On operationally defining reconciliation

Post-conflict reconciliatory behavior has been reported to occur with variable frequencies in different primate groups and species. Because different investigators have used different criteria to operationalize reconciliation, however, it is possible that the variation reported merely reflects different methods of study. To compare different groups and species in a meaningful way, an accurate operationalization of reconciliation is necessary. This study explores the correlation between operationally defined reconciliation (what observers recognize, such as friendly reunion) and functional reconciliation (behavior that restores a dyadic social relationship) in a group of captive long-tailed macaques, using results from an experiment originally undertaken to demonstrate the function of friendly reunions in restoring dyadic tolerance after aggression. In dyads of unrelated animals, reunions were equally effective in restoring tolerance whether they involved body contact, overt friendly gestures, or mere proximity. Classification of post-conflict reunions as “reconciliations” depends on comparisons with control observations; these comparisons have been carried out in several ways. Comparisons using the “n-minute rule” missed functional reconciliations, whereas those based on the “post-conflict/matched-control rule” appeared to lead to more accurate classification of functional reconciliations. Post-conflict reunions were equally effective in restoring tolerance whether they were initiated by the original aggressor or by the victim. An accurate operational definition of reconciliation, not a conservative one, is prerequisite to comparisons of the frequency of this behavior, and depends on empirical verification. This study suggests specific guidelines for an operational definition based on such verification. © 1993 Wiley-Liss, Inc.     

Post-Conflict Affiliation in Barbary Macaques is Influenced by Conflict Characteristics and Relationship Quality, but Does Not Diminish Short-Term Renewed Aggression

Many group living primates have evolved mechanisms to repair their social relationships after conflicts ('reconciliation'). We analysed the post-conflict behaviour of female Barbary macaques, Macaca sylvanus , living in the enclosure 'La Forêt des Singes' at Rocamadour, France. Based on a sample of 914 conflicts, we investigated whether relationship (kinship, rank, affiliation, support and sex) and conflict characteristics (conflict intensity, context and duration) affected the quality and frequency of affiliative post-conflict interactions. Thirty-two per cent of all conflicts were followed by post-conflict affiliation. Rates of socio-positive interactions and support were better predictors of post-conflict affiliation than kinship or rank. Short conflicts were followed by post-conflict affiliation relatively more frequently, after a shorter latency, but only briefly, and such interactions were initiated by both parties equally frequently. The majority of affiliative post-conflict interactions occurred immediately after the end of the conflict. In sum, female Barbary macaques invest more in post-conflict affiliation with valuable partners, and they modulate their post-conflict behaviour in relation to conflict characteristics. Remarkably, affiliative post-conflict interactions increased the short-term probability of renewed aggression by the former aggressor to 16% compared with 9% for conflicts that were not followed by affiliative behaviour. Such renewed aggression after post-conflict affiliation occurred particularly frequently among females and after conflicts over food, suggesting that post-conflict affiliation sometimes falsely lures the former victim to stay in the vicinity, even at the risk of receiving renewed aggression.