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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Boyd, L.,. (1988). The behavior of Przewalski's horses. Ph.D. thesis, , Cornell University.
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Jenks, S. M. (1988). Behavioral regulation of social organization and mating in a captive wolf pack. Ph.D. thesis, Univ. Conn. Dept. Biobehavioral Sci, .
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Boyd L. (1988). The behaviour of Przewalski’s horses. Ph.D. thesis, Cornell University, Ithaca, NY.
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Shaw, E. B., Houpt, K. A., & Holmes, D. F. (1988). Body temperature and behaviour of mares during the last two weeks of pregnancy. Equine Vet J, 20(3), 199–202.
Abstract: Average daily core body temperature and behavioural patterns of pregnant mares were studied, in search of definitive signs of parturition within 24 h of the event. Nineteen pony mares were sampled twice daily for core body temperature. A significant temperature drop, averaging 0.1 degrees C (0.2 degrees F) was observed during the day prior to parturition. Between 18.00 h and 06.00 h, during the two weeks before parturition, Thoroughbred and Standardbred mares (n = 52) spent an average 66.8 per cent of their time standing, 27.0 per cent eating, 4.9 per cent lying in sternal recumbency, 1.0 per cent lying in lateral recumbency, and 0.3 per cent walking. On the night before parturition, mares spent significantly less time lying in sternal recumbency than on previous nights and on the night of parturition all behaviour patterns except eating were significantly different from the nights of the two weeks before parturition. There was an increase in walking (5.3 per cent), lying in sternal recumbency (8 per cent) and lying in lateral recumbency (5.3 per cent) whereas standing (53.3 per cent) was decreased. In 58 observed pregnancies, 54 mares (97 per cent) foaled in a recumbent position and 50 mares (86 per cent) foaled between 18.00 h and 06.00 h.
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Houpt, K. A., Perry, P. J., Hintz, H. F., & Houpt, T. R. (1988). Effect of meal frequency on fluid balance and behavior of ponies. Physiol. Behav., 42(5), 401–407.
Abstract: Twelve ponies were fed their total daily ration either as one large meal or divided into six small meals. Pre- and post-feeding behavior was recorded six times a day. Blood samples were taken for 30 min before and two hr after the meal. Plasma protein increased from 7.0 to a peak of 7.3 g/dl with small meals and from 7.3 to 8.1 g/dl with large meals, and returned to pre-feeding levels by 90 min post-feeding. Hematocrit rose from 33.3 to 34.1% with small meals and from 33.0 to 36.0% with large meals. These rapid and short-lived increases indicate a decrease in plasma volume. Plasma osmolality rose with feeding from 283 to 285 mosmoles/kg with small meals and from 281 to 288 mosmoles/kg with large meals. Water availability had no significant effect on blood changes. Digestibility and rate of passage were measured with chromic oxide, but there were no differences. Vocalizing (neighing) and walking occurred more often before than after feeding, while eating bedding and engaging in other oral behaviors were more frequent after feeding.
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Marinier, S. L., Alexander, A. J., & Waring, G. H. (1988). Flehmen behaviour in the domestic horse: Discrimination of conspecific odours. Appl. Anim. Behav. Sci., 19(3-4), 227–237.
Abstract: American Saddlebred horses were used to test the responses of domestic horses to the odours of conspecifics. In all cases the odours were tested in the absence of the donor animal. Thus the test animal's behavioural responses were concentrated on the olfactory stimuli, and possible interference from donor behaviour was eliminated. Stallions were significantly more responsive than mares and geldings. This was shown in both flehmen and sniffing behaviour to urine/vaginal secretions and in sniffing behaviour to faecal samples. Only stallions were used for subsequent tests. Stallions showed no significant differences in response to the odour of urine/vaginal secretions of an oestrus mare from that when she was not in season. Parameters used for analysis of data were frequency, latency and duration of flehmen as well as duration of responsiveness to samples. In testing for differences in odours between individual mares, two methods were used. The stallions differentiated between samples from individual mares. In some cases this differentiation was exhibited when the stallions were merely presented with the two samples in sequence. In other cases statistically significant differences in response to the odours were shown only by simultaneous presentation of the two samples to the test stallion. Parameters used for data analysis were frequency and duration of flehmen and duration of responsiveness.
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Houston, A. I., & McNamara, J. M. (1988). Fighting for food: a dynamic version of the Hawk-Dove game. Evol. Ecol., 2(1), 51–64.
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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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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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