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Krueger, K., & Koenig von Borstel, U. (2014). Wie Pferde lernen. In Deutsche Reiterliche Vereinigung e.V. (Ed.), Pferde verstehen – Umgang und Bodenarbeit (pp. 56–82). Warendorf: FN Verlag der deutschen Reiterlichen Vereinigung GmbH.
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Quaresmini, C., Forrester, G. S., Spiezio, C., & Vallortigara, G. (2014). Social environment elicits lateralized behaviors in gorillas (Gorilla gorilla gorilla) and chimpanzees (Pan troglodytes). Journal of Comparative Psychology, 128(3), 276–284.
Abstract: The influence of the social environment on lateralized behaviors has now been investigated across a wide variety of animal species. New evidence suggests that the social environment can modulate behavior. Currently, there is a paucity of data relating to how primates navigate their environmental space, and investigations that consider the naturalistic context of the individual are few and fragmented. Moreover, there are competing theories about whether only the right or rather both cerebral hemispheres are involved in the processing of social stimuli, especially in emotion processing. Here we provide the first report of lateralized social behaviors elicited by great apes. We employed a continuous focal animal sampling method to record the spontaneous interactions of a captive zoo-living colony of chimpanzees (Pan troglodytes) and a biological family group of peer-reared western lowland gorillas (Gorilla gorilla gorilla). We specifically focused on which side of the body (i.e., front, rear, left, right) the focal individual preferred to keep conspecifics. Utilizing a newly developed quantitative corpus-coding scheme, analysis revealed both chimpanzees and gorillas demonstrated a significant group-level preference for focal individuals to keep conspecifics positioned to the front of them compared with behind them. More interestingly, both groups also manifested a population-level bias to keep conspecifics on their left side compared with their right side. Our findings suggest a social processing dominance of the right hemisphere for context-specific social environments. Results are discussed in light of the evolutionary adaptive value of social stimulus as a triggering factor for the manifestation of group-level lateralized behaviors. (PsycINFO Database Record (c) 2016 APA, all rights reserved)
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Nuñez, C. M. V., Adelman, J. S., Smith, J., Gesquiere, L. R., & Rubenstein, D. I. (2014). Linking social environment and stress physiology in feral mares (Equus caballus): Group transfers elevate fecal cortisol levels. General and Comparative Endocrinology, 196, 26–33.
Abstract: Abstract Feral horses (Equus caballus) have a complex social structure, the stability of which is important to their overall health. Behavioral and demographic research has shown that decreases in group (or band) stability reduce female fitness, but the potential effects on the physiological stress response have not been demonstrated. To fully understand how band stability affects group-member fitness, we need to understand not only behavioral and demographic, but also physiological consequences of decreases to that stability. We studied group changes in feral mares (an activity that induces instability, including both male and female aggression) on Shackleford Banks, NC. We found that mares in the midst of changing groups exhibit increased fecal cortisol levels. In addition, mares making more group transfers show higher levels of cortisol two weeks post-behavior. These results offer insights into how social instability is integrated into an animal’s physiological phenotype. In addition, our results have important implications for feral horse management. On Shackleford Banks, mares contracepted with porcine zona pellucida (PZP) make approximately 10 times as many group changes as do untreated mares. Such animals may therefore be at higher risk of chronic stress. These results support the growing consensus that links between behavior and physiological stress must be taken into account when managing for healthy, functional populations.
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Wathan, J., & McComb, K. (2014). The eyes and ears are visual indicators of attention in domestic horses. Current Biology, 24(15), R677–R679.
Abstract: Summary Sensitivity to the attentional states of others has adaptive advantages [1], and in social animals, attending to others is important for predator detection, as well as a pre-requisite for normal social functioning and more complex socio-cognitive abilities [2]. Despite widespread interest in how social species perceive attention in others, studies of non-human animals have been inconclusive about the detailed cues involved [3]. Previous work has focused on head and eye direction, overlooking the fact that many mammals have obvious and mobile ears that could act as a visual cue to attention. Here we report that horses use the head orientation of a conspecific to locate food, but that this ability is disrupted when parts of the face (the eyes and ears) are covered up with naturalistic masks. The ability to correctly judge attention also interacted with the identity of the model horse, suggesting that individual differences in facial features may influence the salience of cues. Our results indicate that a combination of head orientation with facial expression, specifically involving both the eyes and ears, is necessary for communicating social attention. These findings emphasise that in order to understand how attention is communicated in non-human animals, it is essential to consider a broad range of cues.
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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.
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Giese,, C. Giese, Gerber,, V. Gerber, Howald,, M. Howald, et al. (2014). Stressbelastung und Verhalten von Pferden in stromführenden gegenüber nicht stromführenden Führanlagen. SAT, 156(4), 163–169.
Abstract: Um die Stressbelastung von Pferden in Führanlagen zu vergleichen, wurden 12 Pferde während 3 Wochen in einer Führanlage mit und ohne stromführenden (3.7 kV) Abtrennungen bewegt. Zur Ermittlung der Stressbelastung wurden die Cortisolwerte im Blut gemessen, die Herzschlagfrequenz mittels Polar® registriert und das Verhalten erfasst. Weder die Cortisol- noch die Herzfrequenzmessungen zeigten einen bedeutenden signifikanten Unterschied zwischen Pferden, die in einer stromführenden beziehungsweise nicht stromführenden Führanlage gingen. Die höchsten Cortisol- und Herzfrequenzwerte wurden in der ersten Woche (Angewöhnungsphase) verzeichnet. Signifikante Unterschiede wurden bei den Verhaltensparametern «Spontanes Wechseln des Abteils» und «Kontakt mit der Trennwand» beobachtet: Während solche vor allem in der ersten Woche und vor dem ersten Stromeinsatz vorkamen, zeigte kein Pferd einen Abteilwechsel während und nach dem Stromeinsatz. Die Resultate dieser Studie deuten darauf hin, dass der Einsatz von stromführenden Abtrennungen in Führanlagen für Pferde keinen bedeutenden messbaren Stress verursacht.
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Austin, N. P., & Rogers, L. J. (2014). Lateralization of agonistic and vigilance responses in Przewalski horses (Equus przewalskii). Applied Animal Behaviour Science, 151, 43–50.
Abstract: tEye and limb preferences were scored in the closest undomesticated relative of Equuscaballus using the same methods as used previously to study laterality in feral horses.Observations were made of 33 Przewalski horses (Equus ferus przewalskii) (male N = 20,female N = 13) living under natural social conditions on a large reserve in France. Signifi-cant left-eye/side biases were found in agonistic interactions within harem bands (M ± SEbias to left 58% ± 0.01 for threats, P < 0.001; 68% ± 0.05 for attacks; P < 0.001) and in stallionfights (threats, 52% ± 0.01 left, P < 0.001; attacks, 63% ± 0.02 left, P < 0.001): as many as 80%of the horses were significantly lateralized in attack responses within harem bands. Lat-erality of vigilance was measured as lifting up the head from grazing and turning it to theleft or right side: a directional bias to the left was found (M ± SE 53% ± 0.02 left, P < 0.001).Side bias in reactivity was calculated as the percent of head lifts above the level of thewithers on the left or right side and this was also left side biased (M ± SE 73% ± 0.03 left,P < 0.001). These results indicate right-hemisphere specialization for control of aggressionand responses to novelty. The left bias in attack scores within harem bands was strongerin males than females (P = 0.024) and in immature than adult horses (P = 0.032). Immaturehorses were also more strongly lateralized than adults in vigilance scores (P = 0.022), whichmay suggest that experience reduces these side biases. Our results show that Przewalskihorses exhibit left eye preferences, as do feral horses, and do so even more strongly thanferal horses. Considering feral and Przewalski horses together, we deduce that ancestralhorses had similar lateral biases. Also similar to feral horses, the Przewalski horses showedno significant forelimb preference at the group level or in the majority of horses at theindividual level, confirming the hypothesis that previously reported limb preferences indomestic breeds are entrained or generated by breed-specific selection.
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Trögel, D., Wolter, R., & Krueger, K. (2014). Fallstudie zum Platzangebot, Verhalten und Wohlbefinden der Pferde (Equus caballus) in Mehrraum-Außenlaufställen mit Aus-lauf und Bewegungsställen [A case study to space, behavior and well-being of horses (Equus caballus) in open stables and open active stables]. In KTBL Schriften. Darmstadt.
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Benz, B., Münzing, C., Krueger, K., & Winter, D. (2014). Ethologische Untersuchung von Heuraufen in der Pferdehaltung [Ethological investigation of hayracks in equine husbandry]. Landtechnik, 69(5), 239–244.
Abstract: Eine tiergerechte, physiologisch und anatomisch auf die Bedürfnisse der Pferde ausgerichtete
Raufutterversorgung sollte die Kaubedürfnisse und die Beschäftigungszeiten von Pferden
ausreichend berücksichtigen. Daher – und auch aufgrund des bestehenden Kostendrucks bei
Raufutter – steigt das Interesse an Raufutterraufen, durch die möglicherweise die Futteraufnahmezeiten
verlängert sowie Futterverluste minimiert werden können.
Die vorliegende Untersuchung vergleicht das Fressverhalten und die Körperhaltung von acht
Pferden beim Einsatz von drei unterschiedlichen Futterraufen mit der Bodenfütterung in Einzelboxenhaltung.
Die Ergebnisse dieser Studie lassen den Schluss zu, dass der Einsatz von
Raufutterraufen die Futteraufnahmezeiten verlängert und somit längere Beschäftigungszeiten
für die Futteraufnahme gewährleistet werden. Außerdem konnte festgestellt werden, dass die
Pferde das Raufutter bei einer der drei untersuchten Raufen überwiegend mit natürlicher Kopf-
Hals-Haltung aufnahmen.
[Regarding the species horse, an appropriate supply of roughage should take into account the
need to chew as well as the need for occupation. In this context, and due to the current cost
pressure for hay, the interest in roughage racks increases. It is assumed that roughage racks
could help to extend the feeding time and reduce food losses.
The present study places the emphasis on the observation of the feeding behaviour of eight
horses in single horse boxes. Three different roughage racks are compared to traditional feeding
on the floor. On the basis of the results it may be concluded that the use of roughage racks
extends the feeding time and thus ensures longer occupation. In one of the three roughage
racks investigated the horses mainly eat in a natural posture of their head and neck.]
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Jennings, D. J. (2014). Limited evidence that visual lateralization is associated with fitness in rutting male fallow deer. Anim. Behav., 92, 85–91.
Abstract: Under certain models of animal competition, individuals are expected to gather information about opponent quality in order to determine whether they should fight or withdraw. However, the ability to process complex information differs between individuals and across brain hemispheres: a feature of vertebrate cognition known as lateralization that is not anticipated by contest models. I investigated the relationship between aggressive behaviour and mating success during the fallow deer, Dama dama, rut and a measure of lateralization derived from eye preference during parallel walking. Results show that there was no relationship between the tendency to escalate to fighting or predictability in the tendency to engage in fighting and lateralization. Conversely, there was a quadratic relationship between third-party intervention behaviour and lateralization: the greater the tendency to intervene in ongoing fights the lower the degree of lateralization. However, individuals that showed lateralization for right-eye use were least likely to be targeted by the intervening male; thus lateralization is beneficial in this context because targeted males are highly likely to lose this subsequent encounter. The relationship between lateralization and mating success was also nonlinear: males that showed little evidence for an eye bias during lateral displays had the greatest mating success. Taken together, individuals that showed lateralization benefited from avoiding being targeted after third-party intervention; conversely, individuals that showed little evidence for lateralization actively intervened during ongoing fights and had higher mating success. These results suggest that, although lateralization does appear to confer a fitness advantage on individuals, this is not as extensive as anticipated.
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