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Berger, J. (1983). Induced abortion and social factors in wild horses. Nature, 303(5912), 59–61.
Abstract: Much evidence now suggests that the postnatal killing of young in primates and carnivores, and induced abortions in some rodents, are evolved traits exerting strong selective pressures on adult male and female behaviour. Among ungulates it is perplexing that either no species have developed convergent tactics or that these behaviours are not reported, especially as ungulates have social systems similar to those of members of the above groups. Only in captive horses (Equus caballus) has infant killing been reported. It has been estimated that 40,000 wild horses live in remote areas of the Great Basin Desert of North America (US Department of Interior (Bureau of Land Management), unpublished report), where they occur in harems (females and young) defended by males. Here I present evidence that, rather than killing infants directly, invading males induce abortions in females unprotected by their resident stallions and these females are then inseminated by the new males.
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Hogan, D. E., Zentall, T. R., & Pace, G. (1983). Control of pigeons' matching-to-sample performance by differential sample response requirements. Am J Psychol, 96(1), 37–49.
Abstract: Pigeons were trained on a matching-to-sample task in which sample hue and required sample-specific observing behavior provided redundant, relevant cues for correct choices. On trials that involved red and yellow hues as comparison stimuli, a fixed-ratio 16 schedule (FR 16) was required to illuminate the comparisons when the sample was red, and a differential-reinforcement-of-low-rates 3-sec schedule (DRL 3-sec) was required when the sample was yellow. On trials involving blue and green hues as comparison stimuli, an FR 16 schedule was required when the sample was blue and a DRL 3-sec schedule was required when the sample was green. For some pigeons, a 0-sec delay intervened between sample offset and comparison onset, whereas other pigeons experienced a random mixture of 0-sec and 2-sec delay trials. Test trial performance at 0-sec delay indicated that sample-specific behavior controlled choice performance considerably more than sample hue did. Test performance was independent of whether original training involved all 0-sec delay trials or a mixture of 0-sec and 2-sec delays. Sample-specific observing response requirements appear to facilitate pigeons' matching-to-sample performance by strengthening associations between the observing response and correct choice.
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Waring, G. H. (Ed.). (1983). Horse Behavior: The Behavioral Traits and Adaptations of Domestic and Wild Horses, Including Ponies. Park Ridge: Noyes Publications.
Abstract: ReviewsSynopsisThe second edition of this informative book remains the most comprehensive and current overview of the behavioral traits and adaptations of horses. The book integrates findings from hundreds of international researchers to provide the reader with a factual synthesis of the behaviour of domestic and feral horses. Building on the strengths of the first edition, the author has thoroughly updated coverage of horse ancestry, development, perception, learning, play, social behavioral manipulation, maintenance activities, and sexual behaviour. Throughout these and other chapters, more emphasis has been given to animal husbandry and management. Additionally, the second edition includes an all-new section on ecological influences on activity patterns, habitat utilization, social behaviour and reproduction. An expanded section on applied ethnology provides behavioral considerations or management and insight regarding the behavioral indicators of horse health and well being. This is followed with an updated appendix listing behavioral symptoms and possible causes. The text contains numerous tables and nearly 100 illustrations and photos. Interesting Facts: Rich with international data, incorporated into text, tables, and figures Two new chapters on ecological influences dealing with interactions between environment feeding, ranging, shelter seeking, reproductive and social behavior, among other topics New chapter on behavioral considerations in horse management, plus updated material on health and well being, surveys atypical symptoms ranging from posture to social behaviour Update appendix provides an extensive listing of behavioral symptoms, with identifications of possible associated problems.
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Baer, K. L., Potter, G. D., Friend, T. H., & Beaver, B. V. (1983). Observation effects on learning in horses. Appl. Animal. Ethol., 11(2), 123–129.
Abstract: Sixteen horses, divided into 2 groups of 8, were used to study observational learning in horses. One group served as controls while the other group served as the treated group (observers). Observers were allowed to watch a correctly performed discrimination task for 5 days prior to testing their learning response using the same task. Discrimination testing was conducted on all horses daily for 14 days, with criterion set at 7 out of 8 responses correct with the last 5 consecutively correct. The maximum number of trials performed without reaching criterion was limited to 20 per day. Mean trials to criteria (MT) by group were: control, 11.25; observer, 10.70. Mean error (ME) scores were: control, 2.37; observer, 2.02. Average initial discrimination error scores were 11.13 for control and 10.38 for observers (P < 0.10). Asymptote was reached by Day 8 for both control and observer groups. Analysis of variance with repeated measures showed an extreme-day effect indicative of learning (P < 0.01), with non-significant differences in learning rate between experimental groups. Whether the initial ability of the horses to perform a discrimination learning task was enhanced by observation of other horses' performance of that task was not obvious from these data.
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Appleby, M. C. (1983). The probability of linearity in hierarchies. Anim. Behav., 31(2), 600–608.
Abstract: The common practice of ranking a group of animals in the closest possible order to a linear dominance hierarchy assumes that dominance among those animals is generally transitive. In fact, analysis of groups in which dominance relationships are random shows that this method has a surprisingly high probability of producing an apparently linear or near-linear hierarchy by chance. As such, the existence of transitive dominance should be tested before it is used in ranking. A suitable statistical test is described here. Chance may also contribute to the linear appearance of hierarchies based on other factors.
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Carson, K., & Wood-Gush, D. G. M. (1983). Equine behaviour: II. A review of the literature on feeding, eliminative and resting behaviour. Appl. Animal. Ethol., 10(3), 179–190.
Abstract: The literature on the feeding, eliminative and resting behaviour of horses has been reviewed to collate the information available on these subjects. The grazing and eliminative behaviour patterns of domestic horses are unlike those of free-ranging Equidae. The reasons for this are not known, but it can cause wasted grazing of up to 90% of a field. Certain conditions, such as provision of supplementary hay and lack of available herbage, can cause these behaviour patterns to change, although it is not known how to manipulate the grazing behaviour of horses to prevent deterioration of the pasture. Grazing behaviour is influenced by many variables and is more complex than the feeding behaviour of a stabled horse. Horses sleep for approximately 12% of the day and show 4 different sleep/wakefulness states -- alert wakefulness, drowsiness, slow-wave sleep and paradoxical sleep. Horses are able to maintain slow-wave sleep while standing, but they need to lie down for paradoxical sleep to occur, rarely spending more than 30 consecutive minutes in lateral recumbency.
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Langlois, B., Minkema, D., & Bruns, E. (1983). Genetic problems in horse breeding. Livestock Production Science, 10(1), 69–81.
Abstract: The purpose of this paper is to give a short survey of the present problems concerning the genetic improvement of horse breeds. The evolution of these populations in Europe, characterized by a deep change from production of draught horses towards that of leisure horses, is described and the influence of the demographical parameters on the selection of these horse populations, is discussed. The generation interval represents an important handicap only surmounted in the case of racing breeds where a high selection intensity can be practised since all animals are subjected to performance testing. In the other cases, the farmer usually does not use modern breeding techniques, but uses crosses instead, which lead more easily to visible results. The available selection criteria are also dealt with. A distinction is made between direct estimates evaluating the abilities of the animals in practice and the indirect estimates measuring a character in correlation to previous ones. For the former estimates, a distinction is made between those resulting from competitions (handicap, records or earnings) and those resulting from direct in-station measurements (saddle, jumping, dressage abilities, draught power). For the indirect estimates, often used especially for the selection of mares, the most important analysis is obviously that of the conformation. However, in the future early selection criteria according to more physiological data should be sought and developed. Estimation of the breeding value according to a given ability is thereafter pointed out. There are two situations: “the panmictic case” concerning sport and draught horses and “the non-panmictic case” corresponding to racing horses, which give rise to some problems. The setting up of breeding plans is discussed. Due to the different economic situations and various objectives of horse production, conclusions are drawn about the role played by geneticists in the present development of this sector.
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