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Boyd, L. E., Carbonaro, D. A., & Houpt, K. A. (1988). The 24-hour time budget of Przewalski horses. Appl. Anim. Behav. Sci., 21(1-2), 5–17.
Abstract: A herd of 8 Przewalski horses were observed on pasture in summer. Fifteen-minute focal animal samples were used to determine the time budget of the horses during the periods 00.00-04.00, 04.00-08.00, 08.00-12.00, 12.00-16.00, 16.00-20.00 and 20.00-24.00 h EDT. The behavioral states recorded were feeding (grazing and eating grain), nursing, drinking, standing, stand-resting, self-grooming, mutual grooming, locomoting, playing, and lying laterally and sternally. The average number of behavioral states occurring per hour, and the defecation, urination, aggression and vocalization rates were also determined. Overall, the horses spent 46.4 +/- 5.9% of their time feeding, 1.3 +/- 0.1% nursing, 0.5 +/- 0.1% drinking, 20.6 +/- 5.4% standing, 15.7 +/- 3.2% stand-resting, 1.7 +/- 0.2% self-grooming, 2.2 +/- 0.7% mutual grooming, 7.4 +/- 1.0% locomoting, 1.2 +/- 0.3% playing, 1.2 +/- 0.5% lying laterally and 4.1 +/- 3.0% lying sternally. The horses averaged 45.2 +/- 5.8 behavioral states per hour, and 0.2 +/- 0.0 defecations, 0.3 +/- 0.0 urinations, 1.5 +/- 0.3 aggressions and 0.7 +/- 0.1 vocalizations per hour. The horses spent the greatest amount of time foraging between 20.00 and 04.00 h, when the temperatures were lower. They spent 68.2 +/- 2.2% of their time between 20.00 and 24.00 h feeding, but only 31.2 +/- 2.1% of their time feeding between 08.00 and 12.00 h. Recumbent rest was most common between 00.00 and 04.00 h. As temperatures rose during the daylight hours, the horses spent more time drinking and standing, rather than grazing. Stand-resting was the most common form of rest during the day. The horses exhibited the greatest number of activities per hour from 08.00 to 20.00 h. While standing in close proximity to one another during these hours, the horses exhibited the highest number of aggressions per hour (1.9-2.4).
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Penzhorn, B. L., & van der Merwe, N. J. (1988). Testis size and onset of spermatogenesis in Cape mountain zebras (Equus zebra zebra). J Reprod Fert, 83, 371–375.
Abstract: Testis mass of adult Cape mountain zebra stallions (mean 70·0 g) was appreciably less than that of other zebra species and domestic horses. The histological appearance of the testes of 11-, 24- and 29-month-old colts was typically prepubertal. Spermatogenic activity of a 4-year-old stallion obtained at the end of summer was at a very low level, while a 4·5-year-old stallion obtained 6 weeks after the winter solstice showed a marked increase in spermatogenesis compared with the 4-year-old. Stallions 6·5-19 years of age collected in different seasons all showed active spermatogenesis.
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Hayes, K. (1988). Temperament tip-offs. Horse and Rider, 11, 47–84.
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Whiten, A., & Byrne, R. W. (1988). Tactical deception in primates. Behav. Brain Sci., 11(02), 233–244.
Abstract: ABSTRACT Tactical deception occurs when an individual is able to use an “honest” act from his normal repertoire in a different context to mislead familiar individuals. Although primates have a reputation for social skill, most primate groups are so intimate that any deception is likely to be subtle and infrequent. Published records are sparse and often anecdotal. We have solicited new records from many primatologists and searched for repeating patterns. This has revealed several different forms of deceptive tactic, which we classify in terms of the function they perform. For each class, we sketch the features of another individual's state of mind that an individual acting with deceptive intent must be able to represent, thus acting as a “natural psychologist.” Our analysis will sharpen attention to apparent taxonomic differences. Before these findings can be generalized, however, behavioral scientists must agree on some fundamental methodological and theoretical questions in the study of the evolution of social cognition.
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Klimov, V. V. (1988). Spatial-ethological organization of the herd of Przewalski horses (Equus przewalskii) in Askania-Nova. Appl. Anim. Behav. Sci., 21(1-2), 99–115.
Abstract: The ethological structure of the herd of Przewalski horses includes hierarchic ranks of horses which determine their social roles in the herd. Besides the age ranks, the wild horses are characterized by the formation of harem groups, a “leading” group of females, a group of bachelor stallions, family groups, etc. The ethological structure determines the spatial one, which is the form of distribution of horses over the territory, and its assimilation and transformation into a system of informative spatial units. Under the influence of “internal” and “external” stimuli, the intragoup regulatory mechanims (social adaptations) manifest themselves, which allow the herd to function in the complicated situation of the reserve and allow humans to control the herd by using these mechanisms. There are grounds to believe that, given the balanced ethological structure of these groups, wild horses could be successfully acclimatized into natural biotopes.
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Berger, J.,. (1988). Social systems, resources, and phylogenetic inertia: an experimental test and its limitations. In C. N. Slobochikoff (Ed.), Ecology of Social Behavior (pp. 157–186). San Diego: Academic Press.
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Ginsberg, J. R. (1988). Social organisation and mating strategies of an arid adapted equid: The Grevy`s zebra. Ph.D. thesis, Princeton University, Princeton.
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Keiper, R. R. (1988). Social interactions of the Przewalski horse (Equus przewalskii Poliakov, 1881) herd at the Munich Zoo. Appl. Anim. Behav. Sci., 21(1-2), 89–97.
Abstract: Data were collected on 972 aggressions and 233 acts of mutual grooming in a herd of 9 Przewalski horses in the Hellabrunn Tierpark in Munich, West Germany. The herd was composed of 1 adult stallion, 5 adult mares and 3 foals. A distinct linear dominance hierarchy was present in the herd, with the stallion being the top-ranking animal. Age was significantly correlated with rank. Almost 40% of all aggressions consisted of herding actions by the stallion. Threats to bite (20% of all aggressions) and threats to kick (11.4%) were next in frequency of occurrence. Most mutual grooms (71%) involved grooming the front part of the body. Although mutual grooming may be used to appease higher-ranked animals, most grooming bouts were between related horses. Foals initiate 47.6% of all allogrooming. Mutual grooming may reduce weaning conflict between a mare and her foal or may result in female coalitions that defend against predators or aggression by the herd stallion.
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Kolter, L., & Zimmermann, W. (1988). Social behaviour of Przewalski horses (Equus p. przewalskii) in the Cologne Zoo and its consequences for management and housing. Appl. Anim. Behav. Sci., 21(1-2), 117–145.
Abstract: Between 1977 and 1986, two actual rank changes and two unsuccessful attempts occurred among the mares of the Cologne herd. The stallion was at first a low-ranking individual, but attained a dominant position during the last 3 years. At this time he started to split his group and thus to affect attachment relationships among his mares. During his absence of half a year, new bonds resulted and disappeared again some months after his return. Foals were tolerated by the sire for a long time. His behaviour to young, sub-adult mares varied with the individual. Protection of sub-adult mares by adult mares against the stallion's attacks may occur. Young mares protect and guard strange foals from their very first day. Management steps to cope with social and feeding problems consisted of enlargement and adding complexity to the enclosure, the establishment of more feeding sites, building a stable and temporary removal of the stallion.
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Feh, C. (1988). Social behaviour and relationships of Prezewalski horses in Dutch semi-reserves. Appl. Anim. Behav. Sci., 21(1-2), 71–87.
Abstract: A short-term study was made of 2 groups of Przewalski horses, a bachelor group of 4 juvenile stallions in Ooij Polder and a harem group of 1 stallion and 4 mares. All social interactions were recorded and the nearest and farthest neighbour was noted. Correspondence analysis was used to determine what parameters determined the relationships among the horses. There was a linear hierarchy among the bachelor stallions. The dominant stallion of the group was also the oldest. The hierarchy was not linear in the harem group, and the 3-year-old stallion was subordinate to the 5-year-old mares. He was also most likely to be farthest from other horses. The mares of the same age, who had also arrived in the park at the same time, tended to be one another's nearest neighbours. The frequency of aggression is higher among Przewalski horses than among domestic horses of similar ages. Correspondence analysis revealed that head-threats and other forms of aggression accounted for more of the variance in the data than any other behaviour, but submission, play and social interactions also contributed.
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