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Wolfe Ml,. (1986). Population dynamics of feral horses in western North America. J Equine Vet Sc, 6, 231–235.
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YALDEN DW et al,. (1986). Catalogue of the mammals of Ethiopia 6; II. order Perissodactyla; A. Family Equidae Monitore Zool italiano Suppl, 21, 35–41.
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Fao,. (1986). The Przewalski horse and restoration to its natural habitat in Mongolia. JO FAO Animal Production and Health Paper. Animal Production and Health Paper, 61.
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Lima, S. L. (1986). Predation Risk and Unpredictable Feeding Conditions: Determinants of Body Mass in Birds. Ecology, 67(2), 377–385.
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Voith, V. L. (1986). Principles of learning. The Veterinary clinics of North America. Equine practice, 2(3), 485–506.
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Liang, K. - Y., & Zeger, S. L. (1986). Longitudinal data analysis using generalized linear models. Biometrika, 73(1), 13–22.
Abstract: This paper proposes an extension of generalized linear models to the analysis of longitudinal data. We introduce a class of estimating equations that give consistent estimates of the regression parameters and of their variance under mild assumptions about the time dependence. The estimating equations are derived without specifying the joint distribution of a subject's observations yet they reduce to the score equations for niultivariate Gaussian outcomes. Asymptotic theory is presented for the general class of estimators. Specific cases in which we assume independence, m-dependence and exchangeable correlation structures from each subject are discussed. Efficiency of the pioposecl estimators in two simple situations is considered. The approach is closely related to quasi-likelihood.
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Berger, J. (1986). Wild horses of the Great Basin. Chicago: University of Chicago Press.
Abstract: Describes the behavior of wild horses living in the Great Basin Desert of Nevada and discusses the role of the horses in the area's ecology
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Keiper, R. R., & Sambraus, H. H. (1986). The stability of equine dominance hierarchies and the effects of kinship, proximity and foaling status on hierarchy rank. Appl. Anim. Behav. Sci., 16(2), 121–130.
Abstract: Dominance hierarchies were determined in four bands of feral horses living on Assateague Island. The bands varied in size from 10 to 16 horses, and consisted of one stallion, several mares and their offspring. The animals ranged in age from less than 1 to over 18 years. Field observation of all social interactions during the summer of 1981 was used to determine dominance. 1981 hierarchies for three of the bands were compared with hierarchies determined for the same bands in 1978, and showed that hierarchies change over time. Age was significantly correlated with rank. Mares with foals did not rank any higher in the hierarchies than mares without foals. Kinship did not appear to have an effect on dominance rank either, since neither juvenile nor adult offspring ranks correlated with the ranks of their mothers. The band stallion was not the highest-ranking animal of any band, but the location of the stallion peripheral to the main body of the band, the nature of his interactions with band members, and his length of residence in the band may have contributed to his low rank.
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Eccles, T. R., & Shackleton, D. M. (1986). Correlates and consequences of social status in female bighorn sheep. Anim. Behav., 34(5), 1392–1401.
Abstract: Dominance-subordinance relationships among a captive group of adule bighorn sheep (Ovis canadensis californiana) were studied from May 1977 to December 1978. Social interactions between females were brief in duration and infrequent. Although a dominance hierarchy was evident among the females, it was not linear. Horn length and body weight were not consistently correlated with social status. The highest ranking females were the most aggressive individuals, initiating more agonistic interactions than subordinates. Females with high social status did not have higher quality diets, lower activity costs, or higher productivity than low ranking females.
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Baker, A. E. M., & Crawford, B. H. (1986). Observational learning in horses. Appl. Anim. Behav. Sci., 15(1), 7–13.
Abstract: This experiment was designed to determine if a horse could learn the location of grain by watching another horse find grain in one of two feed buckets. Both experimental and control groups contained 9 quarter horses consisting of five 2-year-old mares, two 2-year-old geldings, and two 3-year-old geldings. Two mature geldings were used as “demonstrators”. An “experimental” was a horse that could watch three times daily another horse, the “demonstrator”, choose between and eat grain from a black or white bucket, only one of which contained grain. A “control” was a horse that could watch a demonstrator in the same arena for 3 min daily when both feed buckets were removed. When the demonstrator was removed on each of 15 successive days, the experimental or control horse was given five trials to determine if it could find the feed bucket with grain. No significant difference between experimentals and controls occurred for both first and total correct choices and for time to reach the feed bucket with grain. We conclude that no observational learning occurred. This experiment was also used to determine if the identity of horses that learned rapidly by trial and error could be predicted by the time it took to reach the feed bucket with grain. Data from the last three trials of experimentals and controls were combined. Significantly less time to find feed was needed by horses with more than the median number of correct choices. Both number of correct choices and time needed to contact a feed bucket summed over the first 5 days accurately predicted the same data summed over the last 10 days. We conclude that horses that learn rapidly by trial and error make correct choices rapidly, and that these horses can by identified after 5 days of testing.
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