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Wolter, R., & Krueger, K. (2015). The analysis of social bonds in feral horses. In Proceedings of the 3. International Equine Science Meeting.
Abstract: In many social mammals, individuals preferentially affiliate with a small subset of available partners instead of distributing their social behaviors equally among all group members. The resulting social bonds have been investigated in several mammalian taxa, especially in primate societies, but also in other taxa such as birds, dolphins, rodents and ungulates. In feral horses, a great number of studies on social bonds can be found, but with a huge variety between methods for the analysis. There seems to be a lack of a clear and common definition of social bonds in horses and of comparable analyses. For example, there are irregularities between the studies regarding the research designs, the selection of recording methods and the interpretation of the measurements. Mutual grooming is used most often for the analysis of social relationships in many species. As mutual grooming is rare in horses, especially measurements of spatial proximity are commonly used for the analysis of social bonds in addition to other behavioral patterns. However, the combination of mutual grooming and nearest neighborhood analyses for the analysis of social bond is debatable, as in contrast to mutual grooming, which must occur deliberately by both grooming partners, the spatial distribution can be influenced by one partner alone, which may even force the other horse to keep a certain distance or to stay in close proximity.
In this study, we investigated the comparability of mutual grooming and nearest neighborhood data for social bond analyses in feral horses. Therefore, we observed five groups of semi-wild living Przewalski’s horses and six groups of feral horses. We analysed the horses’ social ranks by applying an Average Dominance Index, we recorded the distances between the animals and observed the number of mutual grooming events as well as friendly approaches. Our results show that there was only a weak correlation between the frequency of staying in nearest neighborhood and mutual grooming in all observed horse groups. In contrast to this, the correlation between the number of friendly approaches and mutual grooming events was higher in most groups. Hierarchies did not affect social bonds, as mutual grooming was similarly induced by higher and lower ranking animals and the social rank did not affect the choice of the grooming partner. Similarly, likelihoods of staying in the neighborhood of particular animals were not affected by the animals’ social rank. The grooming frequencies differed between the different horse groups and between the individual horses living in the particular groups. They seem to be effected by individual predisposition. Altogether we suggest that the ratio of mutual grooming seems to be a better indicator for social bonds in feral horses than the frequency of staying in the nearest neighborhood. Mutual grooming occurs deliberately and is bidirectional, whereas nearest neighborhoods could be enforced and unidirectional. For the calculation of social bonds in horses, we consider it to be more reliable to combine the frequency of mutual grooming with the frequency of friendly approaches. |
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Obergfell, J. (2012). Einf lus s v on St ruktur e l ement en auf da s Li eg ev e rha l t en v on Pf e rden in Gruppenha l tung unt e r Be rücks i cht igung de s Ag g r e s s i ons v e rha l t ens. Ph.D. thesis, , Karlsruhe.
Abstract: Durch die vorliegende Studie wurde der Einfluss von Strukturelementen auf das Liege- und Aggressionsverhalten von Pferden in Gruppenhaltung untersucht. Die Strukturelemente sollten Rückzugsmöglichkeiten bieten, sowie in ihrem Bereich zur Aufhebung der Individualdistanz führen und dadurch die Fläche relativ vergrößern. Für die Versuche stellte das Haupt- und Landesgestüt Marbach drei unabhängige Pferdegruppen mit verschiedener Herdengröße zur Verfügung, die jeweils in Einraum- Innenlaufställen gehalten wurden. Die Datenerfassung fand zwischen 23 und sieben Uhr statt. Insgesamt wurden 366 Stunden Videomaterial ausgewertet. Beim Ruheverhalten wurden mit Hilfe des event-sampling- Verfahrens die Parameter Gesamtliegedauer, Dauer in Seitenlage, Dauer der Einzelphasen in
Seitenlage und Abliegehäufigkeit pro Nacht erfasst. Es wurden Versuchsphasen ohne Strukturelemente und mit hängenden Planen als Strukturierung durchgeführt. Im ersten Stall kamen außerdem über einander gestapelte Strohballen zum Einsatz. Diese Art der Strukturierung stellte sich jedoch als nicht praktikabel heraus und führte im Vergleich zu den Planen zu einer signifikanten Verschlechterung der Gesamtliegedauer. In Stall 1 konnte man eine tendenzielle Verbesserung der Parameter Gesamtliegedauer und Gesamtdauer in Seitenlage durch das Anbringen von Planen sehen. In Stall 3 dagegen verschlechterte sich das Ruheverhalten in den Versuchsphasen mit Planen gegenüber den Versuchsphasen ohne Struktur. Die Werte der Gesamtdauer in Seitenlage nahmen signifikant ab. In Stall 2 zeigten sich keine Unterschiede in den verschiedenen Versuchsphasen. Möglicherweise ist die Wirkung der Strukturelemente auf das Liegeverhalten abhängig von der Flächengröße. Stall 1 hatte bezogen auf die Leitlinien des BMELV die größte und Stall 3 die kleinste Fläche. Bei den anderen Parametern des Liegeverhaltens gab es keine signifikanten Unterschiede in den verschiedenen Versuchsphasen. Mit Hilfe des time-sampling-Verfahrens wurde die Anzahl gleichzeitig liegender Pferde und gleichzeitig liegender Pferde in Seitenlage bestimmt. Auch hier zeigten sich keine Unterschiede in den verschiedenen Versuchsphasen. Bei der Gegenüberstellung der Werte der Gesamtliegedauer und der Gesamtdauer in Seitenlage mit dem Alter der Pferde (Stall 1 und Stall 3) und mit dem Integrationszeitpunkt (Stall 1) konnte kein Zusammenhang festgestellt werden. Beim Aggressionsverhalten wurden mit Hilfe des event-sampling-Verfahrens in den Ställen 2 und 3 verschiedene Arten von Aggressionen erfasst, die dann in die drei Intensitätsgrade Low-Level-, Mid-Level- und High-Level- Aggressionen unterteilt wurden. Neben der Anzahl wurde die Dauer der verschiedenen Aggressionen bewertet. Insgesamt konnte eine positive Wirkung der Planen auf das Aggressionsverhalten beobachtet werden. Die Gesamtanzahl an Aggressionen nahm in beiden Ställen tendenziell in den Versuchsphasen mit Planen ab. In Stall 3 konnte, wenn man die Aggressionen stundenweise betrachtet, ein signifikanter Unterschied festgestellt werden. Auch der Hinterhandschlag und die Aggressionen, welche das Ruheverhalten stören, verringerten sich tendenziell nach dem Anbringen von Strukturelementen. In beiden Ställen nahm die relative Häufigkeit von Mid-Level-Aggressionen nach dem Anbringen von Planen zu. Dagegen konnte bei den High-Level-Aggressionen und in Stall 3 bei den Low-Level- Aggressionen eine relative Abnahme beobachtet werden. Sowohl die Anzahl als auch die Dauer der Mid-Level-Aggressionen verringerten sich in Stall 3 stundenweise betrachtet signifikant in den Versuchsphasen mit Planen. In Stall 2 war bei den High-Level- Aggressionen sowohl bei der Dauer als auch bei der Anzahl eine signifikante Abnahme zu sehen. Wenn man das Aggressionsverhalten in Bezug zu der Fläche in den zwei Ställen betrachtet, schien diese vor allem einen Einfluss auf die High-Level-Aggressionen zu nehmen. Mit Hilfe des Rangindex der Pferde im Stall 3 wurde eine Rangordnung aufgestellt. Zwischen dem Platz der Pferde in der Rangordnung und den Parametern des Ruheverhaltens (Gesamtliegedauer, Gesamtdauer in Seitenlage) sowie dem Alter der Pferde konnte kein Zusammenhang festgestellt werden. Zwischen dem Rangindex und der Gesamtanzahl an Aggressionen bestand dagegen ein hoch signifikanter Zusammenhang. Im Rahmen dieser Studie ist das Anbringen von Strukturelementen in Bezug auf das Aggressionsverhalten in Einraum-Innenlaufställen von Pferden zu empfehlen. Die Wirkung auf das Liegeverhalten der Pferde sollte in weiteren Studien untersucht werden. [In this study the influence of structural elements on lying and aggression behavior in horses kept in groups was exanimated. Structural elements should offer the possibility of retreat. Furthermore, within the respective area, the individual distance should be limited, thus increasing the overall space relatively. For the studies the “Haupt- und Landesgestüt Marbach” provided three non-related groups of different sized horses, each kept in separate “Einraum-Innenlaufställen”. Data collection took place between 11 pm and 7 am. Altogether, 366 hours of video material were analyzed. Using the event-sampling-method, the following parameters within the horses´ resting behavior were determined: The total lying period, the total lying period in lateral position, the periods of the single lying in lateral position and the frequency of lying down. Test phases were carried out without structural elements and with hanging canvases as structural elements. In the first stable there were also three bales of straw piled up on top of each other. This kind of structuring emerged as impractical and in comparison to the canvas, led to a significant deterioration to the total period of lying. After the canvases were fixed in the first stable, a slight improvement with the parameters of total lying period and total lying period in the lateral position could be seen. In contrast, the resting behavior in stable 3 worsened in the test phases with the canvases in comparison to the test phases without structural elements. The values for the total lying period in the lateral position decreased significantly. In stable 2, there were no differences in the different test phases. Possibly the effect of the structural elements is dependent of the space. Stable 1 had the largest space and stable 3 the least space referred to the guideline of the BMELV. The other parameters of the lying behavior showed no significant differences in the different test phases. The number of horses lying at the same time, and the number of horses lying at the same time in the lateral position were detected with the aid of the time-sampling-method. There were also no differences between the different test phases. If the values of the total lying period and the total lying period in lateral position were compared to the age of the horses (stable 1 and stable 3) and to the point of integration (stable 1), there was no correlation. Different kinds of aggression were detected by the means of the event-sampling-method in stable 2 and 3 and were subdivided into the three levels of intensity: Low-level-, mid-level and high-level-aggressions. Both the number and the duration of the different aggressions were evaluated. All in all a positive influence of the canvas on the aggression behavior could be observed. In both stables, the total number of aggressions decreased in the test phases with canvases. In stable 3 a significant difference could be detected, if the aggressions were observed per hour. Also hind limb kicks and aggressions disturbing the resting behavior, decreased by trend, after fixing the canvases in the stable. In both stables the relative frequency of mid-level-aggressions increased after the canvases were mounted. In contrast there was a relative decrease at the high-level-aggressions and in stable 3 at the low-levelaggressions. The number and the duration of the mid-level-aggressions in stable 3 decreased, when considered by the hour in the test phases with canvases. In stable 2 a significant decrease in duration and number of high-level-aggressions was observed. When examining aggression behavior in reference to space in the two stables, high-level-aggressions seemed to be mostly influenced. In stable 3 a rank order was established with the aid of the rank index of the horses. There was no correlation between the horses´ rank and the parameters of the resting behavior (the total lying period, the total lying period in lateral position) and between horses´ rank and age. In contrast, there was a high significant correlation between the rank index and the total number of aggressions. In context to this study, structural elements in “Einraum-Innenlaufställen” (BMELV 2009) seem to have a positive influence on the aggression behavior and thus seem to be recommendable. The influence on the lying behavior should be investigated in further studies.] |
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Stashak, T. S., & Wissdorf, H. (2007). Adams' Lahmheit bei Pferden. Hannover: Schaper M. & H.
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Heitor, F., & Vicente, L. (2008). Maternal care and foal social relationships in a herd of Sorraia horses: Influence of maternal rank and experience. Appl. Anim. Behav. Sci., 113(1-3), 189–205.
Abstract: The influence of maternal rank and experience on patterns of maternal care and social relationships of foals were investigated in a managed herd of Sorraia horses, Equus caballus. Social interactions and spatial relationships of 13 foals (seven females and six males) born to seven mares were examined from birth to 10 months of life, within the three major periods of foal development. Conflict over suckling between dam and foal was not generally affected by rank and experience, but higher-ranking mothers allowed more suckling during late lactation than lower-ranking mothers. Foals of higher-ranking mares spent more time in proximity to the mother during socialization. Maternal rank and experience did not significantly affect maternal protectiveness, foal independence from the mother or the development of affiliative relationships between foals and group members. Foals of higher-ranking mares received lower frequencies of aggression from other horses only in the first month of life. Dominance relationships among foals depended mainly on aggressiveness and were not associated with maternal rank. The large variability in maternal behaviour, the absence of a significant association between maternal rank and body condition at parturition and the stable social environment within this herd may partly account for the reported results.
Keywords: Horse; Rank; Experience; Maternal care; Social relationships
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Christensen, J. W., Ahrendt, L. P., Lintrup, R., Gaillard, C., Palme, R., & Malmkvist, J. (2012). Does learning performance in horses relate to fearfulness, baseline stress hormone, and social rank? In Applied Animal Behaviour Science (Vol. 140, pp. 44–52).
Abstract: The ability of horses to learn and remember new tasks is fundamentally important for their use by humans. Fearfulness may, however, interfere with learning, because stimuli in the environment can overshadow signals from the rider or handler. In addition, prolonged high levels of stress hormones can affect neurons within the hippocampus; a brain region central to learning and memory. In a series of experiments, we aimed to investigate the link between performance in two learning tests, the baseline level of stress hormones, measured as faecal cortisol metabolites (FCM), fearfulness, and social rank. Twenty-five geldings (2 or 3 years old) pastured in one group were included in the study. The learning tests were performed by professional trainers and included a number of predefined stages during which the horses were gradually trained to perform exercises, using either negative (NR) or positive reinforcement (PR). Each of the learning tests lasted 3 days; 7min/horse/day. The NR test was repeated in a novel environment. Performance, measured as final stage in the training programme, and heart rate (HR) were recorded. Faeces were collected on four separate days where the horses had been undisturbed at pasture for 48h. Social rank was determined through observations of social interactions during feeding. The fear test was a novel object test during which behaviour and HR were recorded. Performance in the NR and PR learning tests did not correlate. In the NR test, there was a significant, negative correlation between performance and HR in the novel environment (rS=-0.66, P<0.001, i.e. nervous horses had reduced performance), whereas there was no such correlation in the home environment (both NR and PR). Behavioural reactions in the fear test correlated significantly with performance in the NR test in the novel environment (e.g. object alertness and final stage: rS=-0.43, P=0.04), suggesting that performance under unfamiliar, stressful conditions may be predicted by behavioural responses in a fear test. There was a negative correlation between social rank and baseline stress hormones (rS=-0.43, P=0.04), i.e. high rank corresponded to low FCM concentrations, whereas neither rank nor FCM correlated with fearfulness or learning performance. We conclude that performance under stressful conditions is affected by activation of the sympathetic nervous system during training and related to behavioural responses in a standardised fear test. Learning performance in the home environment, however, appears unrelated to fearfulness, social rank and baseline FCM levels.
Keywords: Horse; Learning; Fearfulness; Stress; Reinforcement; Social rank
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Heitor, F., do Mar Oom, M., & Vicente, L. (2006). Social relationships in a herd of Sorraia horses: Part II. Factors affecting affiliative relationships and sexual behaviours. Behav. Process., 73(3), 231–239.
Abstract: The influence of age, dominance rank, kinship and aggressiveness over affiliative relationships and sexual behaviours were analysed in a herd of Sorraia horses, Equus caballus, kept under extensive management. Subjects were 10 adult mares 5-18 years old that had known each other since birth, and a stallion introduced into the group for breeding for the first time. Kinship coefficient and dominance rank were the most important factors affecting affiliative relationships. Bonds were reciprocal and stronger among mares with higher kinship. Mares spent more time in proximity to close-ranking and lower-ranking females. Mares with stronger affiliative relationships or higher relatedness were not less aggressive towards each other. Affiliative relationships between the stallion and the mares were not reciprocal: lower-ranking mares formed stronger bonds with the stallion but he preferred the less genetically related mares for proximity. However, the stallion was involved in sexual behaviours more frequently with the mares that were more genetically related to him. These results suggest that kinship beyond close relatives may affect affiliative relationships both among familiar and among unfamiliar horses. However, the influence of kinship does not imply that horses possess a kin recognition system and alternative explanations are discussed.
Keywords: Horse; Equus; Affiliative relationship; Rank; Kinship; Aggressiveness
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Krueger, K., Flauger, B., Farmer, K., & Hemelrijk, C. (2014). Movement initiation in groups of feral horses. Behav. Process., 103, 91–101.
Abstract: Abstract Herds of ungulates, flocks of birds, swarms of insects and schools of fish move in coordinated groups. Computer models show that only one or very few animals are needed to initiate and direct movement. To investigate initiation mechanisms further, we studied two ways in which movement can be initiated in feral horses: herding, and departure from the group. We examined traits affecting the likelihood of a horse initiating movement i.e. social rank, affiliative relationships, spatial position, and social network. We also investigated whether group members join a movement in dominance rank order. Our results show that whereas herding is exclusive to alpha males, any group member may initiate movement by departure. Social bonds, the number of animals interacted with, and the spatial position were not significantly associated with movement initiation. We did not find movement initiation by departure to be exclusive to any type of individual. Instead we find evidence for a limited form of distributed leadership, with higher ranking animals being followed more often.
Keywords: Horse; Equus ferus caballus; Distributed leadership; Herding; Departure; Rank
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Heitor, F., & Vicente, L. (2010). Dominance relationships and patterns of aggression in a bachelor group of Sorraia horses (Equus caballus). J. Ethol., 28(1), 35–44.
Abstract: Abstract The influence of individual factors on dominance rank and the relationship between rank distance and patterns of aggression predicted by models of evolutionarily stable strategies (ESS) of animal conflict were investigated in a managed bachelor group of Sorraia horses, Equus caballus. The group was composed of four to six stallions 3- to 12-years-old during the study period. The dominance hierarchy was significantly linear and rank was not related to age, weight, height or aggressiveness. Frequency and intensity of agonistic interactions were low, but higher-ranking stallions did not receive lower aggressiveness than lower-ranking stallions. There was some evidence that dominance relationships were more contested among close-ranking stallions, as predicted. Agonistic-related interactions among close-ranking stallions served similar functions to those among distant-ranking stallions, but the latter interacted more frequently than expected for access to resting sites and/or resting partners. Therefore, we found some evidence that agonistic-related interactions among distant-ranking stallions play a larger role in providing access to valuable and defendable resources than those among close-ranking stallions. Nevertheless, the fact that space to escape from aggression was limited and breeding access was independent from dominance rank may have reduced the benefits relative to costs of aggression and therefore limited the occurrence of contests over dominance and resources.
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Krueger, K., & Flauger, B. (2008). Social feeding decisions in horses (Equus caballus). Behav. Process., 78(1), 76–83.
Abstract: Like many other herbivores, in a natural environment equids feed on rather evenly distributed resources. However, the vegetation in their vast habitats constantly changes. If food is plentiful only little competition occurs over food, and in non-competitive situations domestic horses tend to return to the same feeding site until it is overgrazed. In contrast, they compete over limited food for which the social status of the individuals appears to be important. Especially in ruminants several studies have proved an influence of social organisations, rank, sex and the depletion of feeding sites on the feeding behaviour of individuals. However, it is not yet understood whether and how social aspects affect horses“ feeding decisions. Curiosity about the influence of social rank on the horses” feeding decisions between two, equally with high-quality surplus food-filled buckets placed in different social feeding conditions, led us to create the test below. The observer horses were alternately tested with a dominant and a subordinate demonstrator placed in one of the three different positions. We conclude that domestic horses use social cognition and strategic decision making in order to decide where to feed in a social feeding situation. When possible they tend to return to the same, continuously supplied feeding site and switch to an “avoidance tendency” in the presence of dominant horses or when another horse is already feeding there. Thus, the social rank and the position of conspecifics affect the feeding strategy of horses.
Keywords: Feeding decision; Horse; Rank; Social behaviour
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Flauger, B., & Krueger, K. (2012). Social feeding decisions in horses (Equus caballus). In Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: Like many other herbivores equids feed on rather evenly distributed resources. Especially in ruminants several studies have proved the influence of social organisations, rank, sex and the depletion of feeding sites on the feeding behaviour of individuals. However, it is not yet understood whether social aspects affect horses´ feeding decisions. Horses roam on vast habitats with constantly changing vegetation. In non-competitive situations domestic horses tend to return to the same feeding site until it is overgrazed. Whereas, for competition over limited food the social status of the individuals appears to be important. Curiosity about the influence of social rank and different social feeding conditions on the horses´ feeding decisions between two buckets, equally filled with high-quality surplus food, led us to create the test situation described here. The observer horses were alternately tested with a dominant and a subordinate demonstrator placed in one of three different positions. We conclude that domestic horses use cognitive strategic decision making in order to decide where to feed in a social feeding situation. When possible they tend to return to the same, continuously supplied feeding site and switch to an “avoidance tendency” when another horse is already feeding from it or in the presence of a dominant horse. Thus the position and the social rank of conspecifics affect the feeding strategy of horses.
Keywords: Feeding decision; Horse; Rank; Social behaviour
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