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Kawamura, S. (1967). Aggression as studied in troops of Japanese monkeys. UCLA Forum Med Sci, 7, 195–223.
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McDonnell, S. M., & Poulin, A. (2002). Equid play ethogram. Appl. Anim. Behav. Sci., 78(2-4), 263–290.
Abstract: An ethogram of play behavior among equids was developed. Several key English-language studies on equids were reviewed to derive a preliminary inventory of specific behaviors to be included in the ethogram. Our primary observations were based on a herd of semi-feral Shetland-type ponies kept at New Bolton Center, University of Pennsylvania School of Veterinary Medicine, Kennett Square, PA. Greater than 100 h of direct observation and photo-documentation focused specifically on play in order to identify play behaviors to be added to the preliminary inventory and to obtain detailed descriptions of each behavior. Additionally, these observations were supplemented with photographs obtained during several years of observational study of this herd for other purposes, and with the cumulative equid observational experience and study notes of the principal investigator with other equid species. An initial draft was sent out to 18 equine behavior colleagues for review. A total of 38 individual behaviors classified into four distinct categories were included in the ethogram. These included object play (14 entries), play sexual behavior (3 entries), locomotor play (14 entries) and play fighting (7 entries). All of the behaviors catalogued from direct observation of the herd were also found in the equid literature. The resulting ethogram offers a practical tool as a field guide or reference for quantitative research and other studies of equid play behavior as well as for teaching of equid behavior.
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Beaver, B. V. (1986). Aggressive behavior problems. Vet Clin North Am Equine Pract, 2(3), 635–644.
Abstract: Accurate diagnosis of the cause of aggression in horses is essential to determining the appropriate course of action. The affective forms of aggression include fear-induced, pain-induced, intermale, dominance, protective, maternal, learned, and redirected aggressions. Non-affective aggression includes play and sex-related forms. Irritable aggression and hypertestosteronism in mares are medical problems, whereas genetic factors, brain dysfunction, and self-mutilation are also concerns.
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Ord, T. J., & Evans, C. S. (2002). Interactive video playback and opponent assessment in lizards. Behav. Process., 59(2), 55–65.
Abstract: Video playback has been used to explore many issues in animal communication, but the scope of this work has been constrained by the lack of stimulus-subject interaction. In many natural contexts, each participant's signalling behaviour is dependent from moment-to-moment on that of the other. Analyses of acoustic communication demonstrate the value of reproducing such social contingencies. We assessed the utility of interactive playback for studies of visual signalling by comparing the responses of male Jacky dragons, Amphibolurus muricatus, to interactive and non-interactive digital video playbacks of a life-sized conspecific. Displays produced by lizards in the interactive condition had the effect of suppressing the aggressive display of their simulated opponent. Each stimulus sequence generated during an interactive playback was subsequently played to a size-matched control animal. Males that could interact with the video stimulus responded principally with aggressive displays, while those that could not produced a mixture of aggressive and appeasement signals. Adding a degree of receiver responsiveness is hence sufficient to alter the type of signal evoked, even when video stimuli are physically identical. Interactive playback permits the experimental study of a broader range of theoretical topics and can enhance the realism of video stimuli.
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Rubenstein, D. I., & Hack, M. A. (1992). Horse signals: The sounds and scents of fury. Evol. Ecol., 6(3), 254–260.
Abstract: During contests animals typically exchange information about fighting ability. Among feral horses these signals involve olfactory or acoustical elements and each type can effectively terminate contests before physical contact becomes necessary. Dung transplant experiments show that for stallions, irrespective of rank, olfactory signals such as dung sniffing encode information about familiarity suggesting that such signals can be used as signatures. As such they can provide indirect information about fighting ability as long as opponents associate identity with past performance. Play-back experiments, however, show that vocalizations, such as squeals, directly provide information about status regardless of stallion familiarity. Sonographs reveal that squeals of dominants are longer than those of subordinates and that only those of dominants have at their onset high-frequency components.
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Dugatkin, L. A., & Bekoff, M. (2003). Play and the evolution of fairness: a game theory model. Behav. Process., 60(3), 209–214.
Abstract: Bekoff [J. Consci. Stud. 8 (2001) 81] argued that mammalian social play is a useful behavioral phenotype on which to concentrate in order to learn more about the evolution of fairness. Here, we build a game theoretical model designed to formalize some of the ideas laid out by Bekoff, and to examine whether `fair' strategies can in fact be evolutionarily stable. The models we present examine fairness at two different developmental stages during an individual's ontogeny, and hence we create four strategies--fair at time 1/fair at time 2, not fair at time 1/not fair at time 2, fair at time 1/not fair at time 2, not fair at time 1/fair at time 2. Our results suggest that when considering species where fairness can be expressed during two different developmental stages, acting fairly should be more common than never acting fairly. In addition, when no one strategy was evolutionarily stable, we found that all four strategies we model can coexist at evolutionary equilibrium. Even in the absence of an overwhelming database from which to test our model, the general predictions we make have significant implications for the evolution of fairness.
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de Waal, F. B., & Johanowicz, D. L. (1993). Modification of reconciliation behavior through social experience: an experiment with two macaque species. Child Dev, 64(3), 897–908.
Abstract: Reconciliation, defined as a friendly reunion between former opponents shortly after an aggressive encounter, is common in the stumptail macaque (Macaca arctoides) but rare in the rhesus macaque (M. mulatta). Juveniles of the two species were cohoused for 5 months, after which they were observed with conspecifics only. Control rhesus monkeys, matched in age and sex to the experimental subjects, went through the same procedure without exposure to the other species. A threefold increase in the proportion of reconciled fights was measured in the rhesus subjects. The difference emerged gradually during cohousing with the tutor species and was sustained following removal of this species. Other behavior, such as grooming and aggression, decreased over time. It is suggested that the social attitude of the subjects was affected through contact with a species characterized by a more relaxed dominance style.
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Flack, J. C., Jeannotte, L. A., & de Waal, F. B. M. (2004). Play signaling and the perception of social rules by juvenile chimpanzees (Pan troglodytes). J Comp Psychol, 118(2), 149–159.
Abstract: Prescriptive social rules are enforced statistical regularities. The authors investigated whether juvenile chimpanzees (Pan troglodytes) recognize and use enforced statistical regularities to guide dyadic play behavior. They hypothesized (a) that proximity of adults, especially mothers of younger play partners, to play bouts will increase the play signaling of older partners and (b) that when juvenile-juvenile play bouts occur in proximity to adults, older partners will play at a lower intensity than when no adults are present. They found that older and younger partners increase their play signaling in the presence of the mothers of younger partners, particularly as the intensity of play bouts increases. In contrast to their hypothesis, older partners played more roughly when the mothers of younger partners were in proximity. These results suggest that juvenile chimpanzees increase play signaling to prevent termination of the play bouts by mothers of younger partners.
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