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Houpt, K. A., & Fraser, A. F. (1988). Przewalski horses. Appl. Anim. Behav. Sci., 21(1-2), 1–3.
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Kirkpatrick, J. F., Kasman, L. H., Lasley,, B. L., & Turner, J. W. J. (1988). Pregnancy Determination in Uncaptured Feral Horses. J Wildl Manag, 52(2), 305–308.
Abstract: The urinary excretion of estrone sulfate ($\text{E}{1}\text{S}$) by 25 free-roaming feral horses (Equus caballus) was measured by radioimmunoassay applied to extracts of urine-soaked soil. Twelve of 15 mares having $\text{E}{1}\text{S}$ concentrations >1.0 mg/mg creatinine (x = 2.64 +- 1.02 [SD]) produced foals. All 10 mares with $\text{E}{1}\text{S}$ concentrations <1.0 mg/mg creatinine (x = 0.44 +- 0.26) did not foal. Extracting urine from soil and measuring $\text{E}{1}\text{S}$ and creatinine can be used to determine pregnancy in free-roaming feral horses without the stress of capture or immobilization.
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KIRKPATRICK JF et al,. (1988). Pregnancy determination in uncaptured feral Horses based on steroid metabolites in urine – soaked snow and free steroids in feces.
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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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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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KOTERBA AM et al,. (1988). Brathing strategy of the adult horse at rest. J Appl Physiol, 64, 337–346.
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Penzhorn Bl,. (1988). Equus zebra. Mammalian Species, 314, 1–7.
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Ryder, O. A., & Massena, R. (1988). A case of male infanticide in Equus przewalskii. Appl. Anim. Behav. Sci., 21(1-2), 187–190.
Abstract: Following the introduction of a new stallion to a band of E. przewalskii mares two births, both of male foals, resulted in foal death due to injuries sustained in the first day of life. Neither foal was sired by the new herd stallion. The second foal death was the results of an observed attack on the newborn male and is described here. Subsequently births in the same enclosure and, in one instance, to the same mare whose previous foal was killed, were of foals sired by the new stallion and were uneventful, with 3 male foals surviving to date.
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Schilder, M. B. H. (1988). Dominance relationships between adult Plains zebra stallions in semi – captivity. Behaviour, 104(3-4), 300–319.
Abstract: The relationships between 4-5 adult zebra stallions, living in a safari park, were investigated over a period of 5 years. Asymmetries in the distributions of a number of behaviours could be explained by adopting dominance as an intervening variable. Dominance in stallions was of a bipolar nature with on the one hand behaviours representing subordinance and defence, and on the other hand behaviours reinforcing and confirming dominance. Expression of formal dominance seems to play a minor role. The dyadic relationships of stallions differed as to the number of behaviours reflecting dominance relationships. Although often linear rank-orders could be constructed, these rank-orders were not necessarily identical. This means that the concept of dominance is of only limited value for describing relationships between zebra stallions.
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Smielowski, J. (1988). Breeding of the Grevy's Zebra at Polish zoological gardens. Przeglad Zool, 32, 595–597.
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