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PERKINS A et al,. (1979). Age characteristics of feral horses in Montana. Symposium on the Ecology and Behavior of wild and feral Equids, Laramie, , 51–58.
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Potter Rl, H. R. (1979). Feral burro food habits and habitat relations, Grand Canyon National Park, Arizona. Symposium on the Ecology and Behavior of wild and feral Equids, Laramie, , 143–157.
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Quick, J. S., & Warren-Smith, A. K. (). Preliminary investigations of horses' (<em>Equus caballus</em>) responses to different bridles during foundation training. Journal of Veterinary Behavior: Clinical Applications and Research, 4(4), 169–176.
Abstract: Throughout equitation history, bitted bridles have been the primary method of controlling the ridden horse. In response to health and behavioral concerns arising from the use of bitted bridles, bitless bridles offer new methods of steering and control. However, the effectiveness of bitless bridles on horses had not been previously examined scientifically. Therefore, the current study measured behavioral and cardiac responses of horses undergoing foundation training (bridling, long reining, and riding) wearing either a bitted or a bitless bridle.The horses wearing the bitted bridle exhibited more chewing, opening of the mouth, pawing the ground, and tail swishing than those in the bitless bridle. The horses wearing the bitless bridle exhibited more head lowering during long reining compared to those in the bitted bridle. The frequency of chewing, opening the mouth, and head raising decreased as training progressed. The number of steps taken after the application of the halt stimulus was greatest for the horses in the bitted bridle during long reining compared with those in the bitless bridle. During long reining, the heart rate and heart rate variability of the horses were higher for those in a bitted bridle compared with those in a bitless bridle.The results of this study suggest that horses wearing bitless bridles performed at least as well as, if not better than, those in bitted bridles. If the use of bitted bridles does cause discomfort to horses, as suggested by some, then the use of bitless bridles could be beneficial and certainly warrants further investigation.
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Rappolt, G. A., John, J., & Thompson, N. S. (1979). Canine responses to familiar and unfamiliar humans. Aggressive Behavior, 5(2), 155–161.
Abstract: Dogs were observed during controlled approaches by their owners and by strangers. Significant differences between the dogs' responses to their owners and their responses to strangers were found. These results supported the popular belief that dogs respond differently to different persons, and not merely to different situations in which persons are usually encountered.
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Rossdale Pd,. (1968). Perinatal behaviour int the thoroughbred horse. (Vol. Chapt. 15).
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Salter Re,. (1979). Biogeography and habitat. Symposium on the Ecology and Behavior of wild and feral Equids, Laramie, , 129–142.
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TURNER JW et al,. (1979). Quantitative aspects of elimination behavior in feral stallions (Abstract). Symposium on the Ecology and Behavior of wild and feral Equids, Laramie, , 84.
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TURNER JW et al,. (1979). Testicular biopsy in feral stallions. Symposium on the Ecology and Behavior of wild and feral Equids, Laramie, , 41–48.
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Van Doorn G.S., Hengeveld G.M., & Weissing F.J. (2003). The Evolution of Social Dominance I: Two-player Models. Behavior, 140(10), 1305–1332.
Abstract: A difference in dominance rank is an often-used cue to resolve conflicts between two animals without escalated fights. At the group level, adherence to a dominance convention efficiently reduces the costs associated with conflicts, but from an individual's point of view, it is difficult to explain why a low ranking individual should accept its subordinate status. This is especially true if, as suggested by several authors, dominance not necessarily reflects differences in fighting ability but rather results from arbitrary historical asymmetries. According to this idea, rank differentiation emerges from behavioural strategies, referred to as winner and loser effects, in which winners of previous conflicts are more likely to win the current conflict, whereas the losers of previous conflicts are less likely to do so. In order to investigate whether dominance, based on such winner and loser effects, can be evolutionarily stable, we analyse a game theoretical model. The model focuses on an extreme case in which there are no differences in fighting ability between individuals at all. The only asymmetries that may arise between individuals are generated by the outcome of previous conflicts. By means of numerical analysis, we find alternative evolutionarily stable strategies, which all utilize these asymmetries for conventional conflict resolution. One class of these strategies is based on winner and loser effects, thus generating evolutionarily stable dominance relations even in the absence of differences in resource holding potential.
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Van Doorn G.S., Hengeveld G.M., & Weissing F.J. (2003). The Evolution of Social Dominance II: Multi-Player Models. Behavior, 140(10), 1333–1358.
Abstract: The social hierarchies observed in natural systems often show a high degree of transitivity. Transitive hierarchies do not only require rank differentiation within pairs of individuals but also a higher level ordering of relations within the group. Several authors have suggested that the formation of linear hierarchies at the group level is an emergent property of individual behavioural rules, referred to as winner and loser effects. Winner and loser effects occur if winners of previous conflicts are more likely to escalate the current conflict, whereas the losers of previous conflicts are less likely to do so. According to this idea, an individual's position in a hierarchy may not necessarily reflect its fighting ability, but may rather result from arbitrary historical asymmetries, in particular the history of victories and defeats. However, if this is the case, it is difficult to explain from an evolutionary perspective why a low ranking individual should accept its subordinate status. Here we present a game theoretical model to investigate whether winner and loser effects giving rise to transitive hierarchies can evolve and under which conditions they are evolutionarily stable. The main version of the model focuses on an extreme case in which there are no intrinsic differences in fighting ability between individuals. The only asymmetries that may arise between individuals are generated by the outcome of previous conflicts. We show that, at evolutionary equilibrium, these asymmetries can be utilized for conventional conflict resolution. Several evolutionarily stable strategies are based on winner and loser effects and these strategies give rise to transitive hierarchies.
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