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Cameron, E. Z., Linklater, W. L., Stafford, K. J., & Minot, E. O. (2000). Aging and improving reproductive success in horses: declining residual reproductive value or just older and wiser? Behav. Ecol. Sociobiol., 47(4), 243–249.
Abstract: In many mammalian species, female success in raising offspring improves as they age. The residual reproductive value hypothesis predicts that each individual offspring will be more valuable to the mother as she ages because there is less conflict between the current and potential future offspring. Therefore, as mothers age, their investment into individual offspring should increase. Empirical evidence for an influence of declining residual reproductive value on maternal investment is unconvincing. Older mothers may not invest more, but may be more successful due to greater experience, allowing them to target their investment more appropriately (targeted reproductive effort hypothesis). Most studies do not preclude either hypothesis. Mare age significantly influenced maternal investment in feral horses living on the North Island of New Zealand. Older mares, that were more successful at raising foals, were more protective for the first 20 days of life, but less diligent thereafter. Total maternal input by older mothers did not seem to be any greater, but was better targeted at the most critical period for foal survival and a similar pattern was observed in mares that had lost a foal in the previous year. In addition, older mothers were more likely to foal in consecutive years, supporting the hypothesis that they are investing less than younger mares in individual offspring. Therefore, older mothers seem to become more successful by targeting their investment better due to experience, not by investing more in their offspring.
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R. A. Hopkins. CALIFORNIA WILDLIFE HABITAT RELATIONSHIPS SYSTEM (Vol. M174).
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Lampe, J. F., & Andre, J. (2012). Cross-modal recognition of human individuals in domestic horses (Equus caballus). Animal Cognition, 15(4), 623–630.
Abstract: This study has shown that domestic horses are capable of cross-modal recognition of familiar humans. It was demonstrated that horses are able to discriminate between the voices of a familiar and an unfamiliar human without seeing or smelling them at the same moment. Conversely, they were able to discriminate the same persons when only exposed to their visual and olfactory cues, without being stimulated by their voices. A cross-modal expectancy violation setup was employed; subjects were exposed both to trials with incongruent auditory and visual/olfactory identity cues and trials with congruent cues. It was found that subjects responded more quickly, longer and more often in incongruent trials, exhibiting heightened interest in unmatched cues of identity. This suggests that the equine brain is able to integrate multisensory identity cues from a familiar human into a person representation that allows the brain, when deprived of one or two senses, to maintain recognition of this person.
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Baragli, P., Vitale, V., Paoletti, E., Sighieri, C., & Reddon, A. R. (2011). Detour behaviour in horses (Equus caballus). J. Ethol., 29(2), 227–234.
Abstract: The objective of this study was to investigate the ability of horses (Equus caballus) to detour around symmetric and asymmetric obstacles. Ten female Italian saddle horses were each used in three detour tasks. In the first task, the ability to detour around a symmetrical obstacle was evaluated; in the second and third tasks subjects were required to perform a detour around an asymmetrical obstacle with two different degrees of asymmetry. The direction chosen to move around the obstacle and time required to make the detour were recorded. The results suggest that horses have the spatial abilities required to perform detour tasks with both symmetric and asymmetric obstacles. The strategy used to perform the task varied between subjects. For five horses, lateralized behaviour was observed when detouring the obstacle; this was consistently in one direction (three on the left and two on the right). For these horses, no evidence of spatial learning or reasoning was found. The other five horses did not solve this task in a lateralized manner, and a trend towards decreasing lateralization was observed as asymmetry, and hence task difficulty, increased. These non-lateralized horses may have higher spatial reasoning abilities.
Keywords: Detour behaviour; Equus caballus; Horses; Lateralization; Spatial reasoning
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Haring, H. (2005). Development, level and prospects of the german horse breeding. Zuechtungskunde, 77(6), 490–495.
Abstract: The economic impact of the horses of the Federal Republic of Germany has gone up, the statistic numerals verify obviously that Germany took pride of place in Europe in terms of numbers of riders as well as numbers of horses. Successes of German branded horses let their breeders reach the summit worldwide. The carefully agreed breeding programme connects practical cognitions with those of science and permits the leading breeding areas unobstructed space to set their own priorities. Globalisation and rised demand of customers forces breeding associations towards a far-reaching reorganisation because just large powerful institutions can meet these requirements. An end of this process, which scarcely has just begun, cannot yet be conceivable seen. – Eugen Ulmer KG, Stuttgart.
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Kavar, T., & Dovc, P. (2008). Domestication of the horse: Genetic relationships between domestic and wild horses. Livestock Science, 116(1-3), 1–14.
Abstract: To date, a large amount of equine genetic data has been obtained regarding (i) extant domestic horses of various breeds from all over the world, (ii) ancient domestic horses, (iii) the extant Przewalski's wild horse, and (iv) the late Pleistocene wild horse from Eurasia and North America. Here, a review of mtDNA and Y chromosome marker analyses is presented in the context of horse domestication. High matrilineal (mtDNA) diversity, which can be found in both extant and ancient (domestic and wild) horses, has suggested that a high number of wild (and tamed) mares were domesticated. Alternatively, Y chromosome marker analysis revealed a single haplotype in all domestic horses analyzed; interestingly even a small population of extant Przewalski's wild horses showed two different Y chromosome haplotypes. It seems that an extreme male population bottleneck occurred due to domestication, while reduction in the female population was only moderate, leaving about 100 distinct haplotypes. For this reason, we speculate that domestication might have started when the appropriate stallion was found or was obtained by selection. Perhaps it had some unusual but special characteristics which could have accelerated the process of domestication. We doubt that only a single Y chromosome haplotype will be found in present-day domestic horses if there are no important differences between the founder stallion/s and the other stallions that were not included in the domestication. In the Eneolithic, tamed and wild mares have probably been spread all over Eurasia, although the number of animals was most likely very low and the populations were limited to a restricted area (e.g., taming centers). Only two subspecies of wild horses (Tarpan and Przewalski's wild horse) have survived up to recently. During the further process of domestication, mares (tamed or wild) were preferentially crossed to stallions having more desirable characteristics. We assume that mares from different regions varied in their morphology due to adaptation to their local environmental conditions. These data might explain rapid expansion of horse populations, as well as their rapid differentiation into various phenotypes during the early phase of domestication.
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Araba, B. D., & Crowell-Davis, S. L. (1994). Dominance relationships and aggression of foals (Equus caballus). Appl. Anim. Behav. Sci., 41(1-2), 1–25.
Abstract: Studied a herd of 15 Belgian brood-mares and 10 foals. Specific aspects of social structure studied were dominance-subordinance relationships, preferred associates, social spacing, aggression rates, the frequency of aggressions administered down the dominance hierarchy, and interactive play bouts. The rank order of the foals, both before and after weaning, was positively correlated with the rank order of their dams. There was also a significant relationship between a foal's rank and its total aggression or aggression rate per subordinate post-weaning. Higher ranking foals had higher rates of aggression. Over 80% of threats were directed down the dominance hierachy. The play-rank order of the foals, scored by the number of times foal left a play bout, was not significantly correlated with the rank order as scored by agonistic interactions. -from Authors
Keywords: aggression; dominance; horse; Equus caballus
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Péron, F., Ward, R., & Burman, O. (2013). Horses (Equus caballus) discriminate body odour cues from conspecifics. Animal Cognition, , 1–5.
Abstract: Knowledge about social recognition and memory in animals can help us to determine appropriate management and husbandry techniques. In this study, we used a habituation–discrimination procedure to investigate the ability of horses (Equus caballus) to distinguish between the body odour samples of unfamiliar conspecifics. To pick up body odour, we rubbed material on the coat of horses and presented these unknown body odours to 16 different conspecifics of the same sex and similar age. The test consisted of two successive two-min presentations of a sample from one individual (e.g. individual ‘A’) and a simultaneous presentation of samples from individual ‘A’ and a novel individual (e.g. individual ‘B’) during a final third presentation. The results showed that horses, regardless of sex, decreased the time they spent investigating conspecific body odour across the initial two presentations—demonstrating habituation. In the final presentation, the results demonstrated successful discrimination of the previously experienced odour because horses investigated the novel olfactory sample (‘B’) significantly more than the pre-exposed sample (‘A’). Taken together, these findings suggest, for the first time, that horses are able to discriminate two stimuli derived from body odours of unfamiliar conspecifics over short period of time.
Keywords: Body odour; Discrimination; Equus caballus; Habituation; Social memory
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Lansade, L., & Simon, F. (2010). Horses' learning performances are under the influence of several temperamental dimensions. Appl. Anim. Behav. Sci., 125(1-2), 30–37.
Abstract: Learning performances are influenced by many factors, not only breed, age and sex, but also temperament. The purpose of this study was to understand how different temperamental dimensions affect the learning performance of horses, Equus caballus. First, we carried out a series of behavioural tests on 36 Welsh ponies aged 5-7 years to measure five temperamental dimensions: fearfulness (novel area test and surprise test), gregariousness (social isolation test), reactivity to humans (passive human test), tactile sensitivity (von Frey filament test) and activity level (evaluation of locomotor activity during all the tests). We then presented them with two learning tasks (avoidance and backwards-forwards tasks). In the avoidance task they had to learn to jump over a fence when they heard a sound associated with an aversive stimulus (puff of air). In the backwards-forwards task they had to walk forwards or move backwards in response to a tactile or vocal command to obtain a food reward. There was no correlation between performances on the two learning tasks, indicating that learning ability is task-dependent. However, correlations were found between temperamental data and learning performance (Spearman correlations). The ponies that performed the avoidance task best were the most fearful and the most active ones. For instance, the number of trials required to perform 5 consecutive correct responses (learning criterion) was correlated with the variables aimed at measuring fearfulness (way of crossing a novel area: rs = -0.41, P = 0.01 and time to start eating again after a surprise effect: rs = -0.33, P = 0.05) and activity level (frequency of trotting during all the tests: rs = -0.40, P = 0.02). The animals that performed the backwards-forwards task best were the ones that were the least fearful and the most sensitive. For instance, the learning criterion (corresponding to the number of trials taken to achieve five consecutive correct responses) was correlated with the variables aimed at measuring fearfulness (latency to put one foot on the area: rs = 0.43, P = 0.01; way of crossing a novel area: rs = 0.31, P = 0.06; and time to start eating again after a surprise effect: rs = 0.43, P = 0.009) and tactile sensitivity (response to von Frey filaments: rs = -0.44, P = 0.008). This study revealed significant links between temperament and learning abilities that are highly task-dependent.
Keywords: Avoidance task; Equus caballus; Fearfulness; Learning; Personality; Temperament
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Nuñez, C. M. V., Adelman, J. S., Mason, C., & Rubenstein, D. I. (2009). Immunocontraception decreases group fidelity in a feral horse population during the non-breeding season. Appl. Anim. Behav. Sci., 117(1-2), 74–83.
Abstract: The behavioral effects of the immunocontraceptive agent porcine zona pellucida (PZP) have not been adequately studied. Important managerial decisions for several species, including the wild horse (Equus caballus), have been based on this limited research. We studied 30 horses on Shackleford Banks, North Carolina, USA to determine the effects of PZP contraception on female fidelity to the harem male. We examined two classes of females: contracepts, recipients of the PZP vaccine (n = 22); and controls, females that have never received PZP (n = 8). We conducted the study during the non-breeding season from December 2005 to February 2006, totaling 102.2 h of observation. Contracepted mares changed groups more often than control mares (P = 0.04). Contracepts also visited more harem groups than did control mares (P = 0.02) and exhibited more reproductive interest (P = 0.05). For both contracepted and control females, the number of group changes (P = 0.01) and number of groups visited (P = 0.003) decreased with the proportion of years mares were pregnant. Our study shows that the application of PZP has significant consequences for the social behavior of Shackleford Banks horses. In gregarious species such as the horse, PZP application may disrupt social ties among individuals and inhibit normal social functioning at the population level.
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