Peace-making in marsupials: the first study in the red-necked wallaby (Macropus rufogriseus)

Witness for resolution: post-conflict quadratic affiliation in semi-free ranging pigs

In social mammals, post-conflict resolution can involve the reunion of former opponents (reconciliation), spontaneous/solicited post-conflict affiliation of a third party with either opponent (triadic contacts), and affiliation between other individuals (hereafter bystanders; quadratic contacts). Quadratic contacts-possibly informing complex cognitive abilities-have been neglected in post-conflict studies. We investigated quadratic affiliation in semi-free ranging pigs Sus scrofa, at the ethical farm Parva-Domus (Cavagnolo, Italy). Kinship was known. We collected behavioral data on adult pigs (n = 104) via video recordings (43 h) followed by video analyses. Affiliative and anxiety behaviors between bystanders were collected under post-conflict (PC; following a conflict between non-bystanders) and matched-control (MC; no conflict) conditions. Quadratic affiliation was present in pigs, as bystanders affiliated more in PC than MC, and such affiliation was followed by a decrease in the anxiety behaviors of both the interacting bystanders. Thus, quadratic contacts may be partly aimed at reducing one's own anxiety (intrinsic regulation). Quadratic affiliation was highest between closely related bystanders, which suggests that such affiliation may be most effective when close kin is involved. Quadratic affiliation was lowest after reconciliation and spontaneous triadic contacts. This suggests that direct peacemaking between opponents and spontaneous triadic contacts with close kin may most likely replace quadratic affiliation. Hence, pigs can be influenced by the negative events that affect other pigs-but not themselves-and their response may be modulated by social factors. Such non-random quadratic affiliation may point toward the presence of elements of social appraisal abilities in pigs.

Domestic pigs (Sus scrofa) engage in non-random post-conflict affiliation with third parties: cognitive and functional implications

In social mammals, conflict resolution involves the reunion of former opponents (aggressor and victim) after an aggressive event (reconciliation) or post-conflict triadic contacts with a third party, started by either opponent (solicited-TSC) or spontaneously offered by the third party (unsolicited-TUC). These post-conflict strategies can serve different functions, including consolation (specifically when TUCs reduce the victim's anxiety). We investigated the possible presence and modulating factors of such strategies on semi-free ranging pigs (Sus scrofa; N = 104), housed at the ethical farm Parva Domus (Cavagnolo, Italy). Kinship was known. Reconciliation was present and mainly occurred between weakly related pigs to possibly improve tolerant cohabitation. Triadic contacts (all present except aggressor TSCs) mostly occurred between close kin. TSCs enacted by victims reduced neither their post-conflict anxiety behaviors nor further attacks by the previous aggressor, possibly because TSCs remained largely unreciprocated. TUCs towards aggressors did not reduce aggressor post-conflict anxiety but limited aggression redirection towards third parties. TUCs towards the victim reduced the victim but not the third-party's anxiety. However, TUCs may also provide inclusive fitness benefits to third parties by benefiting close kin. In sum, pigs engaged in non-random solicited/unsolicited triadic contacts, which suggests that pigs might possess socio-emotional regulation abilities to change their own or others' experience and elements of social appraisal, necessary to detect the emotional arousal of relevant others and (in case of TUCs) take the agency to restore homeostasis.

Anxiety Behavior in Pigs (Sus scrofa) Decreases Through Affiliation and May Anticipate Threat

Anxiety is a physio-psychological state anticipating an imminent threat. In social mammals it is behaviorally expressed via displacement activities and buffered via affiliation. Anxiety research on domestic pigs (Sus scrofa) has mostly focused on abnormal/stereotypic behavior associated with intensive farming. We investigated how anxiety is expressed and modulated in semi-free ranging pigs, in natural habitats. Owing to pigs' socio-cognitive complexity, we posited that displacement activities, if such, would increase after a (stressful) intra-group aggression (Prediction 1), be reduced by affiliation (Prediction 2) and influenced by individual/contextual factors (Prediction 3). From 224 videos recorded on adult individuals (Mean ± SD/subject: 4.84 ± 1.85 h) at the “Ethical Farm Parva Domus” (Turin, Italy), we extracted possible displacement activities (vacuum-chewing, scratching/body-rubbing, head/body-shaking, and yawning) in four 3-min conditions: before (BA) and after aggression events, in the absence (AA) or presence (AP) of post-aggression affiliation, and a matched-control (no event; MC). We conducted a minute-by-minute analysis in AE/AA and assessed the effect of subjects' involvement in a conflict (aggressor, aggression's recipient, bystander). All activities were higher in AA than in BA condition—thus being anxiety markers—and all of them decreased to baseline levels in AP, faster compared to AE. Hence, anxiety behavior in pigs was socially buffered. Intriguingly, anxiety behavior was expressed significantly more by bystanders than opponents, which suggests that pigs may be able to anticipate imminent threats. By highlighting how anxiety is managed under extensive farming, this study contributes to the understanding of pig welfare and biology.

Back to the Future: A Glance Over Wolf Social Behavior to Understand Dog-Human Relationship

Simple Summary

Wolves, the ancestors of dogs, are one of the most cooperative canine species. This cooperative propensity derives from the fact that each subject needs other group members to obtain resources and increase survival. The pack functions as a unit in which each individual collaborates in territory defence, hunting, and rearing of offspring. For this reason, even though a clear hierarchy exists among wolves, subordinates can provide help to dominants to obtain social tolerance in a sort of commodity exchange. Wolves can make peace after aggression, console victims of a conflict, and calm down the aggressors. This set of behaviors, also called post-conflict strategies, requires a social attentiveness towards others’ emotional state and the ability to coordinate appropriate reactions. Adult wolves also play. They engage in play fighting, which strongly resembles real fighting, by finely modulating their motor actions and quickly interpreting playmates’ intentions, thus maintaining the non-serious playful mood. All these cognitive and social skills were a fertile ground for the artificial selection operated by humans to redirect the cooperative propensity of wolves towards dog–human affective relationship.

Abstract

This review focuses on wolf sociobiology to delineate the traits of cooperative baggage driven by natural selection (wolf-wolf cooperation) and better understand the changes obtained by artificial selection (dog-human cooperation). We selected some behaviors of the dog’s ancestors that provide the basis for the expression of a cooperative society, such as dominance relationships, leverage power, post-aggressive strategies, and playful dynamics between pack members. When possible, we tried to compare the data on wolves with those coming from the dog literature. Wolves can negotiate commodities when the interacting subjects occupy different ranking positions by bargaining social tolerance with helping and support. They are able to manage group disruption by engaging in sophisticated post-conflict maneuvers, thus restoring the relationship between the opponents and reducing the spreading of aggression in the group. Wolves engage in social play also as adults to manipulate social relationships. They are able to flexibly adjust their playful interactions to minimize the risk of escalation. Complex cognitive abilities and communicative skills are probably the main proximate causes for the evolution of inter-specific cooperation in wolves.

USE OF ORAL FLUOXETINE FOR THE TREATMENT OF ABNORMAL AGGRESSION IN TWO RED-NECKED WALLABIES (MACROPUS RUFOGRISEUS)

: Abnormal inter- and intraspecies aggression, perceived to be anxiety related, was identified in two male red-necked wallabies (Macropus rufogriseus) housed within a zoo. Aggressive episodes were directed at conspecifics, other exhibit animals, and, in one case, human caretakers. The clinical use of oral fluoxetine (0.5 mg/kg po bid) for a period of approximately 4 mo was effective in eliminating aggression towards humans and other animals in these two individuals. There was no evidence of recrudescence of aggression in either case following discontinuation of therapy for up to 3 yr posttreatment. Other than a period of mild transient sedation in one animal, side effects were not noted with fluoxetine treatment in these cases. Additional studies on the pharmacokinetics and side effects of fluoxetine treatment for anxiety behaviors are warranted in wallabies.

Social interaction analysis in captive orcas (Orcinus orca)

The management of socially complex species in captivity is challenging. Research on their social behavior improves our understanding of interactions in captive animals and captive-group management. We conducted a detailed analysis of social relationships shown by the orcas kept at Loro Parque zoo and their tendency to reconcile after aggressive episodes. Affiliative interactions were the most frequent social activities compared to agonistic or sexual interactions. Within affiliative behaviors, we documented the pattern "gentle tongue bite", where an animal touches the other's tongue with his teeth but does not bite it. Affiliative interactions between a specific pair of orcas occurred significantly more often than expected by chance, and together with low levels of agonistic interactions, indicated particular affinity between some individuals. The most frequently observed low-level agonistic relationship was that of the two older males (Tekoa-Keto); however, they also showed frequent sexual and affiliative interactions. Sexual-like behaviors (pursuit, mount, and penis between males) were found in both sexes. Finally, the observed corrected conciliatory tendency (31.57%) was within the range described for other primate and cetacean species. This study provides a systematic way to assess social interactions as well as conflict management strategies in cetaceans housed in zoos and zoo-like facilities and may help to improve animal welfare and management of animals in controlled environments.

Reconciliation and third-party affiliation in pair-bond budgerigars (Melopsittacus undulatus)

Some group-living animals show conciliatory tendencies towards specific group members after conflicts, referred to as post-conflict affiliation (PC-affiliation). PC-affiliation with a former opponent and a third-party bystander is classified as ‘reconciliation’ and ‘third-party affiliation’, respectively. PC-affiliation is assumed to be mediated by high-quality social relationships between individuals. Recently, studies assessing lifelong monogamous birds, such as corvids, have found PC-affiliation as a case of convergent evolution with regard to primates. Nevertheless, PC-affiliation divergence in birds is still poorly understood. Here, we report that pair-bonds of budgerigars, a lifelong-monogamous small parrot, engage in both reconciliation and third-party affiliation. We also found that males initiated both types of PC-affiliation more often than females. However, during reconciliation, this skewed affiliation pattern was unlikely specific to the PC-context but could also stem from sex differences in basic social-behavioural features (i.e., female dominance over males and males’ primary role in initiating affiliation with females), which are common outside the PC-context. Conversely, the third-party PC-affiliation pattern was significantly different from the basic affiliation pattern: affiliations were initiated more often by combatant winners, by bystander males toward defeated females, and less often by defeated males. These results suggest specific signal and stress reduction functions related to PC-affiliation among budgerigar pair-bonds. The present study supports the view that PC-affiliations, based on high-quality relationships, did not only evolve in mammals but also in birds, with species-specific forms associated with social behavioural tendencies.

Individual differences in aggressive and peaceful behavior: new insights and future directions

Consistent individual differences in animal behaviour are an increasingly common focus of research across various behavioural and biological sciences. Such ‘animal personalities’ comprise a diverse repertoire of behavioural tendencies, recently expanding to incorporate the social domain. Aggression and peace, hallmarks of many social systems including that of humans, warrant integration with this literature. Specifically, animal personality research should consider the potential role of stable conflict and post-conflict behavioural tendencies. We focus our discussion primarily on examples in nonhuman primates and humans, but suggest that individual variation patterns are relevant for any social species in which these phenomena exist. In highly gregarious species, an individual’s conflict and post-conflict tendencies can affect the strength and stability of its social bonds. Because social relationships in turn impact survival and reproductive success, we also encourage future work to investigate the ultimate (i.e., fitness-relevant) consequences of individual variation in aggressive and peaceful behaviour.

Play, aggressive conflict and reconciliation in pre-school children: what matters?

Play provides children with the opportunity to train in fundamental social skills, including conflict management. Here, we evaluate the management of play, aggressive conflict and reconciliation in 3- to 5-year-old preschool children. 3-year-old children show the highest levels of aggressive conflicts in free play, and do not reconcile their aggressive conflicts in the first months of the preschool year because they still lack social capacities to successfully manage interactions with peers. We found no gender bias in being aggressors or victims, but gender-typed traits were reflected in the expression of aggressiveness in same-sex peers for boys, who rely more on physical contacts than girls. Gender segregation in play is seen only in boys, regardless of age. Our results emphasize the importance of considering play, aggressive conflicts, and reconciliation as a whole, in order to obtain a comprehensive overview of the development of pre- and post-conflict dynamics in humans.

The Season for Peace: Reconciliation in a Despotic Species (Lemur catta)

However despotic a social group may be, managing conflicts of interest is crucial to preserve group living benefits, mainly based on cooperation. In despotic groups, post-conflict management via reconciliation (the first post-conflict reunion between former opponents) can occur, even if conciliatory rates are considerably different. Lemur catta is defined as a despotic species because groups are characterized by a strict linear hierarchy maintained by the adult females (the dominant sex) mainly via aggression. Reconciliation was reported in one out of four captive groups of L. catta. Here we investigate which variables influence the occurrence of reconciliation in these despotic groups. We analyzed 2339 Post Conflict (PC)-Matched Control (MC) observation pairs, collected on eight groups (five in the Berenty forest, Madagascar; three hosted at the Pistoia Zoo, Italy). Since L. catta is characterized by steep female dominance but shows female-female coalitionary support, we expected to confirm the presence of reconciliation in the study species. Consistently, we found reconciliation in one captive group and two wild groups, thus providing the first evidence of the presence of this phenomenon in wild L. catta. Moreover, because this species is a seasonal breeder (with mating occurring once a year), we expected seasonal fluctuations in reconciliation levels. Via a GLMM analysis using data from all wild groups and on a captive group followed for more than one year, we found that season (but not rank; individuals' identity, sex, and age; or group identity) significantly affected individual reconciliation rates, and such rates were lowest during the mating period. Thus, reconciliation can be present in groups in which dominants strongly influence and limit social relationships (steep dominance hierarchy) except when the advantages of intra-group cooperation are overcome by competition, as occurs in seasonal breeders when reproduction is at stake. We conclude that in despotic social groups in which coalitions are observed, the right question is not if but when reconciliation can be present.

Being a victim or an aggressor: Different functions of triadic post-conflict interactions in wolves (Canis lupus lupus)

Animals adopt different behavioral strategies to cope with the conflict of interests coming from the competition over limited resources. Starting from the study on chimpanzees, post-conflict third-party affiliation (the affiliative contact provided by a third-party toward the victim--VTA--or the aggressor--ATA) was investigated mainly in primates. Later, this post-conflict mechanism has been demonstrated also in other mammals, such as wallabies, horses, dolphins, domestic dogs, and wolves. Here, we present data on triadic post-conflict affiliation in wolves (Canis lupus lupus) by exploring some of the hypotheses already proposed for primates and never tested before in other social mammals. In this carnivore species, the study of VTA and ATA revealed that these strategies cannot be considered as a unique behavioral category since they differ in many functional aspects. VTA serves to protect the victim by reducing the likelihood of reiterated attacks from the previous aggressor and to reinforce the relationship shared by the third-party and the victim. On the other hand, ATA has a role in bystander protection by limiting the renewed attacks of the previous aggressor toward uninvolved group-members (potential third-parties). In conclusion, exploring VTA and ATA gives the opportunity to concurrently demonstrate some functional differences in triadic post-conflict affiliation according to the different targets of bystanders (victims or aggressors). The data comparison between primates and other social mammals should permit to open new lines of research.