Kasuya, E. (1995). A randomization test for linearity of dominance hierarchies. J. Ethol., 13(1), 137–140.
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Majolo, B., Ventura, R., & Koyama, N. F. (2009). A Statistical Modelling Approach to the Occurrence and Timing of Reconciliation in Wild Japanese Macaques. Ethology, 115(2), 152–166.
Abstract: 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.
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Heitor, F., & Vicente, L. (2010). Affiliative relationships among Sorraia mares: influence of age, dominance, kinship and reproductive state. J. Ethol., 28(1), 133–140.
Abstract: Abstract Affiliative relationships among mares were examined in a managed group of Sorraia horses, Equus caballus, over a 3-year period. We assessed the influence of age, dominance, kinship and reproductive state on the strength of affiliative relationships and diversity of partners. The herd comprised 9–11 mares that had known each other since birth, their foals and a stallion that remained in the group exclusively during the breeding season. In contrast to a previous study, kinship did not significantly affect bonds. Mares tended to spend more time in proximity to those in the same reproductive state. Affiliative relationships among mares were relatively stable but their strength decreased after foaling, possibly as a function of foal protection and bonding between dam and foal. There was no consistent evidence that mares disengaged from affiliative relationships with increasing age. As expected, dominant mares and barren mares contributed the most to affiliative relationships. Dominance rank increased with age, but dominance relationships were stable and did not change after foaling. Overall, reproductive state was the factor that had the most consistent influence on affiliative relationships among Sorraia mares.
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Vervaecke, H., Stevens, J., Vandemoortele, H., Sigurjönsdöttir, H., & De Vries, H. (2007). Aggression and dominance in matched groups of subadult Icelandic horses (Equus caballus). J. Ethol., 25(3), 239–248.
Abstract: Abstract We studied sex differences in the nature of aggression and dominance behaviour in two newly formed groups of 1-year-old Icelandic horses. One herd contained nine geldings, the other nine mares. The groups were matched with regard to dominance-determining traits such as age, weaning age, composition of native herd, social experience, genetic origin, body condition and maternal dominance status. High-ranking individuals of both sexes were more aggressive, high-ranking males were older, and high-ranking females had a better body condition. Frequencies of aggressions were similar in both groups. The mares reacted significantly more by showing submission upon an aggression rather than by not responding or by escalating the aggression. For the geldings, this difference was not observed due to a lower tendency to submit. A linear dominance hierarchy was found in both groups. David`s scores provided additional information regarding cardinal rank distances and were used to calculate steepness of hierarchies. The female hierarchy was somewhat steeper compared to the male hierarchy, suggesting somewhat lower despotism among males. This was mainly a consequence of the lower unidirectionality in male submission. Male contests occurred predominantly between dyads at top and mid positions, suggesting a low degree of acceptance of the hierarchy.
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Hampton, R. R. (2001). Animal Minds: Beyond Cognition to Consciousness. Ethology, 107, 1055–1056.
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Majolo, B., Ventura, R., & Koyama, N. F. (2009). Anxiety Level Predicts Post-Conflict Behaviour in Wild Japanese Macaques (Macaca fuscata yakui) (Vol. 115). © 2009 Blackwell Verlag GmbH.
Abstract: Reconciliation (i.e. the post-conflict exchange of friendly behaviour between former opponents) functions to control for the detrimental effects that aggression may have on social relationships. Studies conducted so far have investigated intra-individual sources of variation in post-conflict behaviour, showing that animals have a stronger increase in anxiety and are more likely to reconcile after conflicts with valuable partners, such as kin. Much less attention has been given to how differences between individuals in emotional profiles affect post-conflict behaviour. Our aim was to analyse whether inter-individual differences in baseline anxiety levels predicted the magnitude of the increase in anxiety following a conflict and the occurrence of reconciliation. We collected data on two groups of wild Japanese macaques (Macaca fuscata yakui). Animals having a higher baseline level of anxiety had a more dramatic anxious response following a conflict while controlling for a series of factors (e.g. relationship quality between opponents). These more anxious animals were also less likely to reconcile than more relaxed individuals. Therefore, more anxious animals face some social costs by being less able to cope with the post-conflict condition. We propose that differences in anxiety levels may be interpreted as tradeoffs between benefits and costs across conditions. For example, more anxious animals, who are less able to reconcile conflicts, might also be less exploratory and thus face a lower risk to eat unknown, poisonous food.
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Koops, M. A., & Abrahams, M. V. (1999). Assessing the Ideal Free Distribution: Do Guppies Use Aggression as Public Information about Patch Quality? Ethology, 105(9), 737–746.
Abstract: Aggression can be costly to foragers, yet some recent research suggests that foragers should use aggression as a cue to patch quality (the attractive aggression hypothesis). If aggression is predictive of patch quality, then the attractive aggression hypothesis predicts that the distribution of foragers should follow the distribution of aggression. If, instead, aggression is repulsive because it is costly, then the distribution of foragers should diverge from the distribution of aggression. We tested the attractive aggression hypothesis using female guppies, Poecilia reticulata, and found that the distribution of foragers followed the distribution of food, but was unaffected by the distribution of aggression. These data do not support the attractive aggression hypothesis, but instead suggest that the distribution of aggression is a consequence of the distribution of foragers, and that aggression is not used as public information about patch quality.
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Bamford, A. J., Monadjem, A., & Hardy, I. C. W. (2010). Associations of Avian Facial Flushing and Skin Colouration with Agonistic Interaction Outcomes. Ethology, , no-no.
Abstract: Abstract Facial flushing, a colour change caused by variation of blood flow through highly vascularized skin, has been observed in taxonomically diverse bird species but the function of the behaviour has not been assessed. Lappet-faced vultures, Aegypius tracheliotos, have unfeathered heads that can rapidly flush from pink to dark red, and this has been hypothesized to indicate contest ability in vulture gatherings. We show that adults with flushed heads won most interactions against those with pale heads. A previously unnoticed colour variation of the throat, visible only when the head is flushed, was also related to the outcome of interactions: blue-throated adults participated in, and won, more interactions than red-throated adults. We suggest that the non-fixed groups of which lappet-faced vulture populations consist promote the evolution of signals of dominance that can be adjusted extremely rapidly.
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Wolff, A., & Hausberger, M. (1994). Behaviour of foals before weaning may have some genetic basis. Ethology, 96(1), 1–10.
Abstract: In this preliminary study on foal behaviour, 13 French saddlebred foals (2-3 mo old) and their dams were observed on pasture. The most important findings are the interindividual quantitative differences in foal behaviour patterns as well as in the amount of mainly foal-initiated time spent at given distances from their mares. Interindividual differences seem in part due to a sire effect
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Harcourt, J. L., Biau, S., Johnstone, R., & Manica, A. (2010). Boldness and Information Use in Three-Spined Sticklebacks. Ethology, 116(5), 440–447.
Abstract: Abstract In foraging groups, individuals may utilise information from their social environment to aid decision making when choosing where to search for food. Little work has looked at the costs or benefits of behavioural differences, such as consistent individual variation in boldness, with respect to learning ability. Here, we investigate the response of three-spined stickleback (Gasterosteus aculeatus) to ‘social cues’, ‘local enhancement’ and ‘public information’ during foraging tasks. Our results confirm previous work suggesting that this species responds to social cues and local enhancement but not public information. Variation in boldness did not affect the use of different types of information. However, time taken to make a choice and reach a patch varied between fish with different levels of boldness. Contrary to expectation, shy fish were the more variable individuals, having a greater range of reaction times when responding to the tasks. This suggests that individual behavioural differences still play a role when utilising information obtained from the environment and may influence the relative benefits that could result in different contexts.
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