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Uller, C., & Lewis, J. (2009). Horses (Equus caballus) select the greater of two quantities in small numerical contrasts. Anim. Cogn., 12(5), 733–738.
Abstract: Abstract The ability to select the greater numerosity over another in small sets seems to stem from the calculation of which set contains more, and has been taken as evidence of a primordial representation at the roots of the primate numerical system. We tested 56 horses (Equus caballus) in a paradigm previously used with human infants and nonhuman primates. Horses saw two quantities paired in contrasts—2 versus 1, 3 versus 2, 6 versus 4 and a control for volume, 2 versus 1 big—and had to make a choice by snout touching the container holding the numerosity selected. The horses spontaneously selected the greater of the two quantities when the numerosities were small. These results add to evidence showing spontaneous quantity assessment in a variety of species.
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Lemasson, A., Boutin, A., Boivin, S., Blois-Heulin, C., & Hausberger, M. (2009). Horse (Equus caballus) whinnies: a source of social information. Anim. Cogn., 12(5), 693–704.
Abstract: Abstract Many animal species that rely mainly on calls to communicate produce individual acoustic structures, but we wondered whether individuals of species better known as visual communicants, with small vocal repertoires, would also exhibit individual distinctiveness in calls. Moreover, theoretical advances concerning the evolution of social intelligence are usually based on primate species data, but relatively little is known about the social cognitive capacities of non-primate mammals. However, some non-primate species demonstrate auditory recognition of social categories and possess mental representation of their social network. Horses (Equus caballus) form stable social networks and although they display a large range of visual signals, they also use long-distance whinny calls to maintain contact. Here, we investigated the potential existence of individual acoustic signatures in whinny calls and the ability of horses to discriminate by ear individuals varying in their degree of familiarity. Our analysis of the acoustic structure of whinnies of 30 adult domestic horses (ten stallions, ten geldings, ten mares) revealed that some of the frequency and temporal parameters carried reliable information about the caller’s sex, body size and identity. However, no correlations with age were found. Playback experiments evaluated the behavioural significance of this variability. Twelve horses heard either control white noise or whinnies emitted by group members, familiar neighbours or unfamiliar horses. While control sounds did not induce any particular response, horses discriminated the social category of the callers and reacted with a sound-specific behaviour (vigilance and attraction varied with familiarity). Our results support the existence of social knowledge in horses and suggest a process of vocal coding/decoding of information.
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Broom, D. M., Sena, H., & Moynihan, K. L. (2009). Pigs learn what a mirror image represents and use it to obtain information. Anim. Behav., 78(5), 1037–1041.
Abstract: Mirror usage has been taken to indicate some degree of awareness in animals. Can pigs, Sus scrofa, obtain information from a mirror? When put in a pen with a mirror in it, young pigs made movements while apparently looking at their image. After 5 h spent with a mirror, the pigs were shown a familiar food bowl, visible in the mirror but hidden behind a solid barrier. Seven out of eight pigs found the food bowl in a mean of 23 s by going away from the mirror and around the barrier. Naïve pigs shown the same looked behind the mirror. The pigs were not locating the food bowl by odour, did not have a preference for the area where the food bowl was and did not go to that area when the food bowl was visible elsewhere. To use information from a mirror and find a food bowl, each pig must have observed features of its surroundings, remembered these and its own actions, deduced relationships among observed and remembered features and acted accordingly. This ability indicates assessment awareness in pigs. The results may have some effects on the design of housing conditions for pigs and may lead to better pig welfare.
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Ward, C., Trisko, R., & Smuts, B. B. (2009). Third-party interventions in dyadic play between littermates of domestic dogs, Canis lupus familiaris. Anim. Behav., 78(5), 1153–1160.
Abstract: Interventions occur when animals interfere in competitive interactions between two or more individuals. Interveners can alter the nature of the ongoing interaction by targeting one party (attacking, biting) and supporting the other. Three theories have been proposed to account for intervention behaviour: kin selection, reciprocity and direct benefits. The kin selection hypothesis predicts that interveners will selectively support relatives over nonrelatives; the reciprocity hypothesis predicts that when intervener [`]A' supports individual [`]B', later [`]B' will intervene and support [`]A'; and the direct benefits hypothesis predicts that target/support patterns should serve the immediate interests of the intervener. We tested the reciprocity and direct benefits hypotheses by exploring third-party interventions in play fighting among littermates of domestic dogs. Interveners in dyadic play did not preferentially target or support preferred playmates of the intervener. Interveners targeted the dog in the losing role at the time of the intervention, and they did not show reciprocity in support. Taken together, these last two findings suggest that littermates benefit directly and use interventions opportunistically to practise offence behaviours directed at littermates already behaving subordinately. Opportunities to practise targeting in a playful setting may help structure dominance relationships among littermates. Additionally, the tendency for puppies to do what the other is doing (target the dog in the losing role) may pave the way for synchronizing cooperative behaviours during group hunting and territorial defence. The types of behaviours used to intervene changed over development, but the outcome following an intervention remained stable.
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Lonsdorf, E. V., Ross, S. R., Linick, S. A., Milstein, M. S., & Melber, T. N. (2009). An experimental, comparative investigation of tool use in chimpanzees and gorillas. Anim. Behav., 77(5), 1119–1126.
Abstract: Studies of ape tool use have been conducted in captivity since the early 1900s and in the wild since the 1960s. Chimpanzees are the most prolific tool users among the apes, and are known to use more tools than any other nonhuman animal. In contrast, reports of gorilla tool use are rare both in wild and captive settings. Studies of the processes involved in tool use learning have been limited in the wild by the lack of ability to control several unpredictable variables, and in captivity by tool use opportunities that are often presented in non-naturalistic contexts. We attempted to address both of these limitations by providing naïve subjects with a naturalistic tool use device (built to simulate a termite mound) while housed in a more natural social setting to approximate how learning would occur in the wild. Both gorillas and chimpanzees participated in the experiment to allow comparative analyses of acquisition of tool behaviour and the factors that may affect acquisition. Both species showed low frequencies of interaction with the mound in the baseline condition, before baiting with a food reward. Once baited, chimpanzees both attempted and succeeded to extract the reward more quickly than did gorillas. The number of social group members at the mound was significantly higher for chimpanzees than for gorillas and may have affected skill acquisition. We advocate that comparative approaches to skill acquisition and learning are valuable, but that researchers need to be cognizant of species differences in social structure that may affect results.
Keywords: chimpanzee; gorilla; Gorilla gorilla gorilla; Pan troglodytes; social structure; tool use
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Dunbar, R. I. M. (2009). The social brain hypothesis and its implications for social evolution. Annals of Human Biology, 36(5), 562–572.
Abstract: The social brain hypothesis was proposed as an explanation for the fact that primates have unusually large brains for body size compared to all other vertebrates: Primates evolved large brains to manage their unusually complex social systems. Although this proposal has been generalized to all vertebrate taxa as an explanation for brain evolution, recent analyses suggest that the social brain hypothesis takes a very different form in other mammals and birds than it does in anthropoid primates. In primates, there is a quantitative relationship between brain size and social group size (group size is a monotonic function of brain size), presumably because the cognitive demands of sociality place a constraint on the number of individuals that can be maintained in a coherent group. In other mammals and birds, the relationship is a qualitative one: Large brains are associated with categorical differences in mating system, with species that have pairbonded mating systems having the largest brains. It seems that anthropoid primates may have generalized the bonding processes that characterize monogamous pairbonds to other non-reproductive relationships (?friendships?), thereby giving rise to the quantitative relationship between group size and brain size that we find in this taxon. This raises issues about why bonded relationships are cognitively so demanding (and, indeed, raises questions about what a bonded relationship actually is), and when and why primates undertook this change in social style.
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McGreevy, P. D., & McLean, A. N. (2009). Punishment in horse-training and the concept of ethical equitation. J. Vet. Behav., 4(5), 193–197.
Abstract: By definition, punishment makes a response less likely in the future. Because horses are largely trained by negative reinforcement, they are susceptible to inadvertent punishment. Delays in the release of pressure can make desirable responses less likely and thus punish them. This study examines the correct use of negative reinforcement and identifies a continuum between poorly timed negative reinforcement and punishment. It explores some of the problems of non-contingent punishment and the prospect of learned helplessness and experimental neurosis. It concludes by introducing the concept of ethical equitation.
Keywords: conditioning; welfare; ethical equitation; horse; punishment; training
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Zharkikh, T. L., & Andersen, L. (2009). Behaviour of Bachelor Males of the Przewalski Horse (Equus ferus przewalskii) at the Reserve Askania Nova. Zoologische Garten, 78(5-6), 282–299.
Abstract: The aim of this study was to investigate social relationships between Przewalski horses at a high density in a bachelor group housed in a 3.5-ha enclosure. The group consisted of 16 males aged 5 to 16. Behavioural data were collected during 18 days, total 216 h. Fifteen minute focal animal sampling was used; each horse was observed three times a day for a total of 45 min. The occurrence of 25 behaviours was recorded, and group spacing behaviour was studied using nearest neighbour recordings. The group divided into four subgroups; this supports earlier findings of bachelor groups (n>=10) dividing into two or more subgroups if they included several males aged >5 years. The total frequency of social interactions was 14.6±1.1 h-1. Although the density of the group in this study was higher than in other zoos, the males interacted agonistically only 3.6 h-1. The most frequently observed social behaviour categories were friendly interactions. This study shows possibilities to use some investigative behaviours (marking, flehmen, olfactory investigation, etc.) as indicators of social status of animals in a group.
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Hoffmann, G., Bockisch, F. - J., & Kreimeier, P. (2009). Einfluss des Haltungssystems auf die Bewegungsaktivität und Stressbelastung bei Pferden in Auslaufhaltungssystemen. Landbauforschung – vTI Agriculture and Forestry Research, 2(59), 105–112.
Abstract: Frühere Untersuchungen haben gezeigt, dass die tägliche Bewegung für die Gesunderhaltung der Pferde notwendig ist. Inwieweit sich jedoch unterschiedliche Bewegungsangebote auf das Stress-und Bewegungsverhalten von Pferden in einer Gruppen-Auslaufhaltung auswirken und ob der Bewegungsbedarf der Pferde durch eine Auslaufhaltung ohne zusätzliche Bewegung gedeckt werden kann, ist der Literatur bisher nicht zu entnehmen. Daher sollte in der nachfolgend beschriebenen Untersuchung der Frage nachgegangen werden, welche Auswirkungen verschiedene Bewegungsangebote auf die Bewegungsaktivität von Pferden in Gruppen-Auslaufhaltungen haben und ob diese das Wohlbefinden der Tiere beeinflussen. Letzteres wurde durch Messung der Herzfrequenzvariabilität und Bestimmung von Cortisolmetaboliten im Pferdekot erfasst und die Bewegungsaktivität der Pferde wurde mit ALT-Pedometern bestimmt.
Verglichen wurden eine Einzel-und Gruppenhaltung mit jeweils angrenzendem Auslauf, aber ohne eine zusätzliche Bewegung der Pferde außerhalb des Stalls. In drei weiteren Varianten der Gruppenhaltung bekamen die Pferde täglichen Auslauf auf einer unbegrünten Koppel, auf einer Weide oder durch gezielte Bewegung in einer Führanlage. Die Bewegungsaktivität konnte durch die zusätzliche Bewegung in Form von Weide oder Führanlage signifikant gesteigert werden. Ein zusätzliches Bewegungsangebot führte bei den Pferden zu einer Abnahme der Stressbelastung und sollte auch den Pferden ermöglicht werden, die in einer Gruppenhaltung gehalten werden, um ihre physische und psychische Gesundheit zu erhalten. [Former studies confirm the necessity of daily movement for the health of a horse. But so far no description could be found in the literature how different movement offerings impact the stress and movement behaviour of horses in group husbandries with close-by discharge. The same holds true for the question whether a discharge husbandry system can meet the movement requirements of horses if there isn�t any additional movement possibility. The aim of the present study was to examine different movement offerings, their effects on the movement activities of horses in a group horse husbandry with close-by discharge and the impact of the movement on the wellbeing of the animals. The heart rate variability and the concentration of the cortisol metabolites in the horse excrement were analyzed for detecting the wellbeing of the horses. Additionally ALT-Pedometers were used for determining the movement activity. A single and a group husbandry system, each with closeby discharge, were compared when horses had no additional movement outside the stable. In three further variants the group husbandry was supplemented with daily time on a non-grassy pasture land, a pasture or in a horse walker. Pasture or horse walker increased movement activity significantly. Nevertheless an additional movement offering resulted in a lower stress load of the horses and should also be allowed to horses in group husbandry systems to ensure the horse�s physical and mental health.] |
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Rowe, M. L., & Goldin-Meadow, S. (2009). Differences in Early Gesture Explain SES Disparities in Child Vocabulary Size at School Entry. Science, 323(5916), 951–953.
Abstract: Children from low-socioeconomic status (SES) families, on average, arrive at school with smaller vocabularies than children from high-SES families. In an effort to identify precursors to, and possible remedies for, this inequality, we videotaped 50 children from families with a range of different SES interacting with parents at 14 months and assessed their vocabulary skills at 54 months. We found that children from high-SES families frequently used gesture to communicate at 14 months, a relation that was explained by parent gesture use (with speech controlled). In turn, the fact that children from high-SES families have large vocabularies at 54 months was explained by children's gesture use at 14 months. Thus, differences in early gesture help to explain the disparities in vocabulary that children bring with them to school.
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