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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Heitor, F., & Vicente, L. (2010). Affiliative relationships among Sorraia mares: influence of age, dominance, kinship and reproductive state. J. Ethol., 28(1), 133–140.
Abstract: Abstract Affiliative relationships among mares were examined in a managed group of Sorraia horses, Equus caballus, over a 3-year period. We assessed the influence of age, dominance, kinship and reproductive state on the strength of affiliative relationships and diversity of partners. The herd comprised 9–11 mares that had known each other since birth, their foals and a stallion that remained in the group exclusively during the breeding season. In contrast to a previous study, kinship did not significantly affect bonds. Mares tended to spend more time in proximity to those in the same reproductive state. Affiliative relationships among mares were relatively stable but their strength decreased after foaling, possibly as a function of foal protection and bonding between dam and foal. There was no consistent evidence that mares disengaged from affiliative relationships with increasing age. As expected, dominant mares and barren mares contributed the most to affiliative relationships. Dominance rank increased with age, but dominance relationships were stable and did not change after foaling. Overall, reproductive state was the factor that had the most consistent influence on affiliative relationships among Sorraia mares.
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Krueger K., F. K., Byrne R. (2011). The use of sensory laterality for indicating emotional and cognitive reactions on environmental stimuli in animals [Die sensorische Lateralität als Indikator für emotionale und kognitive Reaktionen auf Umweltreize beim Tier]. In M. Erhard, U. Pollmann, B. Puppe, K. Reiter, & S. Waiblinger (Eds.), Current research in applied ethology [Aktuelle Arbeiten zur artgemäßen Tierhaltung (pp. 13–23). Darmstadt: KTBL.
Abstract: Summary
Many animals are lateralized when using sensory organs such as the eyes, ears or nostrils. Sensory laterality is not, as previously believed, caused by adjustment to motor laterality, but rather by one sided information processing in the particular brain hemi-spheres. While the right hemisphere predominantly analyses emotional information, the left hemisphere governs controlled rational, cognitive decisions. Since the brain hemi-spheres are largely connected with contralateral sensory organs, it is possible to infer how the information may be being interpreted by the side of preferred eye, ear or nostril used. The left eye usually dominates in emotional situations, i.e. fear or positive ex-citement, and the right eye in rational situations. Moreover, laterality increases when animals are stressed, e.g. when animals are confronted with anthropogenic or natural factors they can not handle, such as unsuitable housing or training conditions or un-avoidable predation pressure and social competition. A strong or increasing laterality could therefore potentially indicate welfare issues.
Zusammenfassung
Viele Tiere zeigen eine eindeutige sensorische Lateralität, sprich sie benutzen bevor-zugt ein Auge, ein Ohr, oder eine Nüster zur Aufnahme von Sinneseindrücken. Dies korreliert in den meisten Fällen nicht mit der motorischen Lateralität, sondern wird viel mehr durch die einseitige Verarbeitung von Informationen in den jeweiligen Gehirnhe-misphären bedingt. So werden emotionale Reaktionen von der rechten, reaktiven Ge-hirnhemisphäre und rationale Reaktionen von der linken, kognitiven Gehirnhemisphäre gesteuert. Da die Gehirnhälften zum Großen Teil mit den kontrolateralen Sinnesorga-nen verbunden sind lässt die Seite mit welcher Sinneseindrücke aufgenommen werden Schlüsse auf deren Informationsgehalt zu. So zeigen Tiere bei linksseitiger Aufnahme von Sinneseindrücken vermehrt reaktive, emotionalen Reaktionen, wie etwa bei Angst oder freudige Erregung, und bei rechtsseitig aufgenommene Sinneseindrücke eher rationales, gesteuertes Verhalten. Zudem verstärkt sich die sensorische Lateralität wenn Tiere Stress erfahren, sprich wenn sie wiederholt mit Situationen anthropogenen oder natürlichen Ursprungs konfrontiert werden denen sie nicht gewachsen sind, wie etwa bei unpassenden Haltungs- und Trainingsbedingungen, oder bei unausweichli-chem Raubtierdruck und sozialer Konkurrenz. Eine stark ausgeprägte, zunehmende sensorische Lateralität kann daher auf ein beeinträchtigtes Wohlergehen der Tiere hinweisen.
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Humphrey, N. K. (1976). The social function of intellect. In P. P. G. Bateson, & R. A. Hinde (Eds.), Growing Points in Ethology (pp. 303–317). Cambridge: Cambridge University Press.
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Wolter, R., & Krueger, K. (2015). Einflussfaktoren auf das Grooming-Verhalten bei wilden und verwilderten Pferden [Influencing factors on grooming behaviour in wild living horses]. In Current research in applied ethology [Aktuelle Arbeiten zur artgemäßen Tierhaltung] KTBL Schrift 510. Darmstadt: KTBL-Schrift 510.
Abstract: Die soziale Fellpflege wurde bei Equiden intensiv erforscht. Es stellte sich heraus, dass diverse Faktoren das Grooming-Verhalten beeinflussen können. Neben saisonalen Gegebenheiten sind dies vor allem soziale Faktoren, wie das Alter und Geschlecht der Tiere, die Hierarchie und Gruppenzusammensetzung sowie die Verwandtschaftsverhältnisse der Tiere untereinander. Diese Faktoren können sowohl bei der Häufigkeit der sozialen Fellpflege, als auch bei der Wahl des Partners eine entscheidende Rolle spielen. Zudem konnte gezeigt werden, dass auch das Aggressivitätslevel in einer Gruppe Einfluss auf das soziale Verhalten und die soziale Fellpflege nehmen kann. Inwiefern zwei Individuen, die sich häufig groomen, auch bevorzugt beieinander stehen, konnte bislang noch nicht eindeutig gezeigt werden, da es hierzu diverse Studien mit konträren Ergebnisse gibt. Dieser Aspekt sollte zukünftig dringend untersucht werden, da die beiden Datensätze häufig gemeinsam verwendet werden, um soziale Bindungen zu berechnen, ohne dass bislang ein eindeutiger Zusammenhang zwischen ihnen ermittelt werden konnte.
[Summary
Social grooming has been investigated intensively in Equids during the last years and several factors are known to influence the grooming behaviour. Beside seasonal conditions these are especially social factors as age and sex, hierarchy and group composition as well as kinship. These factors can affect the grooming frequencies and influence the choice of the grooming partner. Moreover, it could be demonstrated that the groups’
aggression level can influence the social behaviour and the grooming intensity. If individuals which show an increased grooming frequency often stand in close proximity as well, has not been affirmed, as, so far, no distinct correlation has been demonstrated. This aspect has to be investigated urgently, as both data sets are often used in combination for calculating social bonds.]
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de Waal, F. B. M., & Luttrell, L. M. (1988). Mechanisms of social reciprocity in three primate species: Symmetrical relationship characteristics or cognition? Ethology and Sociobiology, 9(2–4), 101–118.
Abstract: Agonistic intervention behavior was observed in captive groups of chimpanzees (Pan troglodytes), rhesus monkeys (Macaca mulatta), and stumptail monkeys (M. arctoides). Reciprocity correlations of interventions were determined while removing from the data the effects of several symmetrical relationship characteristics, that is, matrillineal kinship, proximity relations, and same-sex combination. It was considered likely that if significant reciprocity persisted after controlling for these characteristics, the reciprocity was based on cognitive mechanisms. Statistical significance was tested by means of recently developed matrix permutation procedures. All three species exhibited significant reciprocity with regard to beneficial interventions, even after controlling for symmetrical traits. Harmful interventions were, however, reciprocal among chimpanzees only. This species showed a “revenge system”, that is, if A often intervened against B, B did the same to A. In contrast, both macaque species showed significantly inversed reciprocity in their harmful interventions: if A often intervened against B, B rarely intervened against A. Further analysis indicates that the strict hierarchy of macaques prevents them from achieving complete reciprocity. Compared to chimpanzees, macaques rarely intervene against higher ranking group members. The observed contrast can be partially explained on the basis of differences in available space, as indicated by a comparison of indoor and outdoor living conditions for the chimpanzee colony. Yet, even when such spatial factors are taken into account, substantial behavior differences between chimpanzees and macaques remain.
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Rutberg, A. T. (1987). Horse Fly Harassment and the Social Behavior of Feral Ponies. Ethology, 75(2), 145–154.
Abstract: Abstract Horse flies (Tabanidae) on and around feral ponies in harem groups were counted at Assateague Island National Seashore, Maryland, U.S.A., between June and August 1985. Harem stallions attracted the most flies; adult mares showed intermediate fly numbers, while few flies landed on foals under any circumstances. The use of thermal and chemical cues by flies selecting a host may have helped create this disparity. When flies were abundant, ponies reduced spacing within the group. Ponies in larger groups suffered from fewer flies than ponies in smaller groups. There was, however, no evidence that ponies merged into larger groups in response to fly harassment, suggesting that biting flies play little role in structuring pony social organization.
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Powell, D. (2008). Female–female competition or male mate choice? Patterns of courtship and breeding behavior among feral horses (Equus caballus) on Assateague Island. J. Ethol., 26(1), 137-144.
Abstract: Previous research on the Assateague horses found that high-ranking females had more surviving offspring than low-ranking females. Variance in reproductive success may be the result of a variety of proximate processes that affect sexual behavior such as mate choice and mate competition. A study was done to determine whether patterns of courtship, social, and sexual behavior could be identified that would suggest mate choice and/or mate competition. Behavioral data were collected from approximately 40 sexually mature mares living in harem bands. Stallions showed more interest in the eliminations of dominant mares than subordinate mares. Males also engaged in significantly more high-intensity (e.g., mounts and copulations) sexual behavior with dominant mares than subordinate mares, and there was a trend for males to engage in more low-intensity (e.g., flehmen and ano-genital sniffing) sexual behavior with dominant mares than subordinate mares. There was no effect of mare rank on spatial relationships with the stallion; however, dominant mares did attempt to restrict reproductive access to the stallion by harassing and disrupting copulations. Higher foaling rates among dominant mares on Assateague Island could therefore be the result of rank-related mate choice by stallions and direct female competition for mating opportunities.
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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.
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Duncan, P. (1982). Foal killing by stallions. Appl. Animal. Ethol., 8(6), 567–570.
Abstract: Feral horses live in social systems similar to those of some species in which infant killing has been reported (e.g. lions), but such behaviour has been reported neither in horses nor in any other ungulate. The results of interviews with owners of free-ranging horses (Camargue breed) are given which show that, though rare, infant killing occurs in this breed, and that it seems to be confined to male foals. It is argued that the observed behaviour cannot simply be considered as pathological, and that close attention should be paid to the possibility that it occurs in wild and feral equids.
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