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Duboscq, J., Agil, M., Engelhardt, A., & Thierry, B. (2014). The function of postconflict interactions: new prospects from the study of a tolerant species of primate. Anim. Behav., 87, 107–120.
Abstract: Aggression can generate anxiety, create uncertainty about its aftermath and jeopardise social relationships. Postconflict interactions serve as conflict management strategies to mitigate these consequences. Whereas postconflict interactions are well characterized in many animals, their functions are still insufficiently investigated. Four functional hypotheses have been proposed: stress reduction, relationship repair, self-protection and benign intent. We aimed to test these hypotheses in females of a tolerant macaque species, the crested macaque, Macaca nigra, under natural conditions, for three postconflict interactions: reconciliation, affiliation and aggression with third parties. Our results provide meaningful contrasts compared with findings in other species. We found no evidence that aggression had consequences for individuals' behavioural indicators of anxiety, although it increased the likelihood of secondary aggression with third parties. There was little evidence for the stress reduction hypothesis as the occurrence of any of the three postconflict interactions investigated had little effect on the measured behavioural indicators of anxiety. Conflict and dyad characteristics also had limited influence on anxiety. The relationship repair function was only partly validated: dyads with stronger bonds or that exchanged more support did not reconcile more often, but dyads with attributes related to the symmetry, stability and predictability (i.e. security) within relationships did. Patterns of initiation and directionality of postconflict interactions in this study population suggest that reconciliation may constitute the signalling of appeasement and benign intent. Furthermore, we found that aggression towards third parties may serve as a source of self-protection and reassertion of the females' social status. The distinctive pattern of postconflict management strategies revealed in wild female crested macaques appears to be related to their typically tolerant social style. These results demonstrate the usefulness of concomitantly studying aggression, postconflict interactions and their functions, to understand conflict management strategies comprehensively, while taking into account the level of social tolerance characterizing the studied society.
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Jennings, D. J. (2014). Limited evidence that visual lateralization is associated with fitness in rutting male fallow deer. Anim. Behav., 92, 85–91.
Abstract: Under certain models of animal competition, individuals are expected to gather information about opponent quality in order to determine whether they should fight or withdraw. However, the ability to process complex information differs between individuals and across brain hemispheres: a feature of vertebrate cognition known as lateralization that is not anticipated by contest models. I investigated the relationship between aggressive behaviour and mating success during the fallow deer, Dama dama, rut and a measure of lateralization derived from eye preference during parallel walking. Results show that there was no relationship between the tendency to escalate to fighting or predictability in the tendency to engage in fighting and lateralization. Conversely, there was a quadratic relationship between third-party intervention behaviour and lateralization: the greater the tendency to intervene in ongoing fights the lower the degree of lateralization. However, individuals that showed lateralization for right-eye use were least likely to be targeted by the intervening male; thus lateralization is beneficial in this context because targeted males are highly likely to lose this subsequent encounter. The relationship between lateralization and mating success was also nonlinear: males that showed little evidence for an eye bias during lateral displays had the greatest mating success. Taken together, individuals that showed lateralization benefited from avoiding being targeted after third-party intervention; conversely, individuals that showed little evidence for lateralization actively intervened during ongoing fights and had higher mating success. These results suggest that, although lateralization does appear to confer a fitness advantage on individuals, this is not as extensive as anticipated.
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Johnstone, R. A. (2001). Eavesdropping and animal conflict. Proc. Natl. Acad. Sci. U.S.A., 98(16), 9177–9180.
Abstract: Fights between pairs of animals frequently take place within a wider social context. The displays exchanged during conflict, and the outcome of an encounter, are often detectable by individuals who are not immediately involved. In at least some species, such bystanders are known to eavesdrop on contests between others, and to modify their behavior toward the contestants in response to the observed interaction. Here, I extend Maynard Smith's well known model of animal aggression, the Hawk-Dove game, to incorporate the possibility of eavesdroppers. I show that some eavesdropping is favored whenever the cost of losing an escalated fight exceeds the value of the contested resource, and that its equilibrium frequency is greatest when costs are relatively high. Eavesdropping reduces the risk of escalated conflict relative to that expected by chance, given the level of aggression in the population. However, it also promotes increased aggression, because it enhances the value of victory. The net result is that escalated conflicts are predicted to occur more frequently when eavesdropping is possible.
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Feuerstein, N., & Terkel, J. (2008). Interrelationships of dogs (Canis familiaris) and cats (Felis catus L.) living under the same roof. Appl. Anim. Behav. Sci., 113(1-3), 150–165.
Abstract: In the process of domestication, dogs (Canis familiaris) and cats (Felis catus) have undergone thousands of years of genetic changes that have adapted them to the human environment. Both species have acquired a global distribution and it has become quite common to find homes with the two living side by side. Nevertheless, there is widespread belief that interspecific communication between dogs and cats is problematic, stemming from their separate evolutionary development and different social structures. Consequently, many people considering possible adoption of both species are concerned about their ability to get along. Interrelationships of dogs and cats living together were studied here in an attempt to determine the main factors influencing the type of relationship likely to develop between the two species. Two approaches were used: (1) a questionnaire completed by owners of both dog(s) and cat(s), which provided a broad database of the animals' behaviors; and (2) observations carried out in participants' homes on their dog-cat interactions. Two separate ethograms for dogs and cats served for analyses of their body language. The findings revealed the following: Both species showed a similar ability to establish a relatively amicable relationship with the other species; the animals' gender had little influence on the nature of their interrelationship; and adoption of the cat prior to the dog appears to conduce to establishing an amicable relationship, as does their first encounter taking place at an early age (up to 6 months of age in cats and up to 1 year in dogs). The findings also suggest that the majority of these dogs and cats understood the particular body language displayed by one animal that has an opposite meaning for the other species; and that the earlier the age of first encounter between the two, the better this understanding. It can be concluded that exposure of both species at an early age to the presence of the other facilitates the learning of each other's body language, and the consequent establishment of an amicable relationship. A better understanding of the various factors that contribute to determining the two species' relationship should not only improve the quality of life of these pets, but also reassure and encourage more people to adopt both cat and dog.
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Meral, Y., Cakiroglu, D., Sancak, A. A., Cyftcy, G., & Karabacak, A. (2007). Relationships between serum serotonin and serum lipid levels, and aggression in horses. Dtsch Tierarztl Wochenschr, 114(1), 30–32.
Abstract: Levels of serum serotonin and serum lipids--triglyceride, total cholesterol, low-density lipoprotein, high-density lipoprotein and very low-density lipoprotein, were determined in normal horses and horses diagnosed with aggression on the basis of a questionnaire survey. Blood serotonin levels in aggressive horses were found to be significantly lower than in non-aggressive horses (P < 0.01), but no association was found with respect to blood lipids.
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Fureix, C., Bourjade, M., Henry, S., Sankey, C., & Hausberger, M. (2012). Exploring aggression regulation in managed groups of horses Equus caballus. Appl. Anim. Behav. Sci., 138(3–4), 216–228.
Abstract: Horses are highly social animals that have evolved to live in social groups. However, in modern husbandry systems, single housing prevails where horses experience social isolation, a challenge-to-welfare factor. One major reason for this single housing is the owners’ concerns that horses may injure each other during aggressive encounters. However, in natural conditions, serious injuries due to aggressive encounters are rare. What could therefore explain the claimed risks of group living for domestic horses? Basing our questioning on the current knowledge of the social life of horses in natural conditions, we review different practices that may lead to higher levels of aggression in horses and propose practical solutions. Observations of natural and feral horses mostly indicate a predominance of low frequencies and mild forms of aggression, based on subtle communication signals and ritualized displays and made possible by group stability (i.e. stable composition), dominance hierarchy and learning of appropriate social skills by young horses. Obviously, adults play a major role here in canalizing undesirable behaviours, and social experience during development, associated with a diversity of social partners, seems to be a prerequisite for the young horse to become socially skilled. Given the natural propensity of horses to have a regulation of aggression in groups, the tendency to display more aggression in groups of domestic horses under some management practices seems clearly related to the conditions offered. We therefore review the managing practices that could trigger aggressiveness in horses. Non social practices (space, resource availability) and social practices (group size, stability of membership, composition and opportunities for social experiences during development) in groups of domestic horses are discussed here. Finally, we propose simple practical solutions leading to more peaceful interactions in groups of domestic horses, based on the knowledge of horses’ natural social life which therefore should be enhanced (e.g. ensuring roughage availability, favouring group stability, introducing socially experienced adults in groups of young horses, etc.). The state of the art indicates that many questions still need to be answered. Given the importance of the associated welfare issues and the consequences on the use of horses, further research is required, which could benefit horses… and humans.
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Ahrendt, L. P., Christensen, J. W., & Ladewig, J. (2012). The ability of horses to learn an instrumental task through social observation. In Applied Animal Behaviour Science (Vol. 139, pp. 105–113).
Abstract: The ability of horses to learn through social observation may ease the implementation of new management systems, because the use of automatic feeders etc. by naive horses could be facilitated by observation of experienced horses. However, previous studies found no documentation for observational learning abilities in horses. This study aimed to investigate the ability of horses to learn an instrumental task from a familiar conspecific when social interaction was allowed during the demonstration. Two similar experiments were performed. In the first experiment, Observer horses (n=11) participated in ten successive demonstrations, where a trained Demonstrator opened an operant device by pushing a sliding lid aside with the muzzle in order to obtain a food reward. Immediately after the demonstrations the Observer horses were given the opportunity to operate the device alone. Control horses (n=11) were aware that the device contained food but were presented to the operant device without demonstration of the task. The learning criterion was at least two openings. Accomplishment of and latency to accomplish the learning criterion, and investigative behaviour towards the operant device were recorded. Five Observers and one Control, out of the eleven horses in each treatment group, accomplished the learning criterion. Even though this presents a high odds ratio (OR) in favour of the Observer treatment (OR=7.6), there was no significant difference between the treatment groups (P=0.15). Analysis of investigative behaviour showed, however, that the demonstrations increased the motivation of the Observer horses to investigate the device. Subsequently, a similar experiment was performed in a practical setting with 44 test horses (mixed age, gender and breed). We used the same operant device and the same number and type of demonstrations, although the horses were held on a loose rope to minimise aggression. In this second experiment, six of 23 Observer horses and five of 21 Control horses learned the instrumental task, representing no influence of the demonstration. Thus, this study did not demonstrate an ability of horses to learn an instrumental task through observation.
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Hemelrijk, C. K., Wantia, J., & Gygax, L. (2005). The construction of dominance order: comparing performance of five methods using an individual-based model. Behaviour, 142(8), 1043–1064.
Abstract: In studies of animal behaviour investigators correlate dominance with all kinds of behavioural
variables, such as reproductive success and foraging success. Many methods are used to
produce a dominance hierarchy from a matrix reflecting the frequency of winning dominance
interactions. These different methods produce different hierarchies. However, it is difficult to
decide which ranking method is best. In this paper, we offer a new procedure for this decision:
we use an individual-based model, called DomWorld, as a test-environment. We choose this
model, because it provides access to both the internal dominance values of artificial agents
(which reflects their fighting power) and the matrix of winning and losing among them and,
in addition, because its behavioural rules are biologically inspired and its group-level patterns
resemble those of real primates. We compare statistically the dominance hierarchy based on
the internal dominance values of the artificial agents with the dominance hierarchy produced
by ranking individuals by (a) their total frequency of winning, (b) their average dominance
index, (c) a refined dominance index, the David`s score, (d) the number of subordinates each
individual has and (e) a ranking method based on maximizing the linear order of the hierarchy.
Because dominance hierarchies may differ depending on group size, type of society, and the
interval of study, we compare these ranking methods for these conditions.We study complete
samples as well as samples randomly chosen to resemble the limitations of observing real
animals. It appears that two methods of medium complexity (the average dominance index
and David`s score) lead to hierarchical orders that come closest to the hierarchy based on
internal dominance values of the agents. We advocate usage of the average dominance index,
because of its computational simplicity.
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Dzieweczynski, T. L., Eklund, A. C., & Rowland, W. J. (2006). Male 11-ketotestosterone levels change as a result of being watched in Siamese fighting fish, Betta splendens. Gen Comp Endocrinol, 147(2), 184–189.
Abstract: This study investigated the effects of nesting status and the presence of an audience on 11-ketotestosterone (11KT) levels in male Siamese fighting fish, Betta splendens. Prior studies have demonstrated that both nesting status, an indicator of territory-holding power and reproductive state, and the sex of a conspecific audience lead to differences in male behavior during aggressive encounters. Since behavioral changes have already been demonstrated, we chose to investigate whether 11KT levels were also influenced by nesting status and audience presence as 11KT both stimulates, and is stimulated by, reproductive and aggressive behaviors in male teleosts. Male 11KT levels were measured from water samples taken from containers holding fish both before and after interaction. Males interacted under three treatment conditions: no audience, female audience, and male audience. Within these treatments were two nest paradigms: both males had nests or neither male had a nest. 11KT levels varied depending on nesting status and audience type. In general, 11KT levels were lower in interacting males when a female audience was present or when males had nests. Overall, 11KT showed increases or decreases as aggression increased or decreased, as shown by already established behavioral findings [see Dzieweczynski T.L., Green T.M., Earley R.L., Rowland W.J., 2005. Audience effect is context dependent in Siamese fighting fish, Betta splendens. Behav. Ecol. 16, 1025-1030; Doutrelant, C., McGregor, P.K., Oliveira, R.F., 2001. Effect of an audience on intrasexual communication in male Siamese fighting fish (Betta splendens). Behav. Ecol. 12, 283-286.]. Our results suggest that 11KT levels are influenced by reproductive status, as indicated by nest ownership, and audience presence and are most likely modulated by territorial behavior and social environment.
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Li, C., Jiang, Z., Tang, S., & Zeng, Y. (2007). Influence of enclosure size and animal density on fecal cortisol concentration and aggression in Pere David's deer stags. Gen Comp Endocrinol, 151(2), 202–209.
Abstract: We investigated the impact of enclosure size and animal density on behavior and adrenocortical secretion in Pere David's deer in Dafeng Nature Reserve, China. From February 15 to April 16 in 2004, we conducted two experiments. First, we studied maintenance behavior and conflict behavior of Pere David's deer stags in a large enclosure (200 ha) with low animal density (0.66 deer/ha) and a small display pen (0.75 ha) with high animal density (25.33 deer/ha). The maintenance behavior we recorded included standing, locomotion, foraging and rest. During the behavioral observations, we collected fresh voided fecal samples from the stags periodically, and analyzed the fecal cortisol concentrations in those samples using radioimmunoassay technique. Second, we monitored the fecal cortisol concentrations of one group of stags (12 deer lived in an enclosure of 100 ha) before and after transferred into a small pen (0.5 ha). We found that in the first experiment: (1) there were significant differences in standing and rest whereas no significant differences of locomotion and foraging between the free-ranging group and the display group; (2) frequency of conflict behavior in the display group was significantly higher than those in the free-ranging group; and (3) fecal cortisol concentration of the display group (326.17+/-16.98 ng/g dry feces) was significantly higher than that of the free-ranging group (268.98+/-15.21 ng/g dry feces). In the second experiment, there was no significant difference of the fecal cortisol concentrations among sampling days, but the mean fecal cortisol concentration of the day after transferring (337.46+/-17.88 ng/g dry feces) was significantly higher than that of the day before transferring (248.44+/-7.99 ng/g dry feces). Comparison with published findings, our results indicated that enclosure size and animal density affect not only behaviors, but also adrenocortical secretion in Pere David's deer. Small living space with high animal density may impose physiological stress to captive Pere David's deer. Moreover, long-term physiological stress and increase of conflict behavior may subsequently affect survival and reproduction of the deer.
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