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| Author | Santamaria, S.; Bobbert, M.E.; Back, W.; Barneveld, A.; van Weeren, P.R. | ||||
| Title | Variation in free jumping technique within and among horses with little experience in show jumping | Type | Journal Article | ||
| Year | 2004 | Publication | American Journal of Veterinary Research | Abbreviated Journal | Am J Vet Res |
| Volume | 65 | Issue | 7 | Pages  |
938-944 |
| Keywords | *Acceleration; Analysis of Variance; Animals; Biomechanics; Forelimb/physiology; Gait/*physiology; Hindlimb/physiology; Horses/*physiology; Locomotion/*physiology; Models, Biological; Video Recording | ||||
| Abstract | OBJECTIVE: To quantify variation in the jumping technique within and among young horses with little jumping experience, establish relationships between kinetic and kinematic variables, and identify a limited set of variables characteristic for detecting differences in jumping performance among horses. ANIMALS: Fifteen 4-year-old Dutch Warmblood horses. PROCEDURE: The horses were raised under standardized conditions and trained in accordance with a fixed protocol for a short period. Subsequently, horses were analyzed kinematically during free jumping over a fence with a height of 1.05 m. RESULTS: Within-horse variation in all variables that quantified jumping technique was smaller than variation among horses. However, some horses had less variation than others. Height of the center of gravity (CG) at the apex of the jump ranged from 1.80 to 2.01 m among horses; this variation could be explained by the variation in vertical velocity of the CG at takeoff (r, 0.78). Horses that had higher vertical velocity at takeoff left the ground and landed again farther from the fence, had shorter push-off phases for the forelimbs and hind limbs, and generated greater vertical acceleration of the CG primarily during the hind limb push-off. However, all horses cleared the fence successfully, independent of jumping technique. CONCLUSIONS AND CLINICAL RELEVANCE: Each horse had its own jumping technique. Differences among techniques were characterized by variations in the vertical velocity of the CG at takeoff. It must be determined whether jumping performance later in life can be predicted from observing free jumps of young horses. | ||||
| Address | Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 12, NL-3584 CM Utrecht, The Netherlands | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 0002-9645 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | PMID:15281652 | Approved | no | ||
| Call Number | Equine Behaviour @ team @ | Serial | 3772 | ||
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| Author | Baldi, R.; Pelliza-Sbriller, A.; Elston, D.; Albon, S. | ||||
| Title | High Potential For Competition Between Guanacos And Sheep In Patagonia | Type | Journal Article | ||
| Year | 2004 | Publication | Journal of Wildlife Management | Abbreviated Journal | |
| Volume | 68 | Issue | 4 | Pages |
924-938 |
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| Abstract | Guanacos (Lama guanicoe) are the largest native Artiodactyl in South America and the most widely distributed. In arid Patagonia, densities are low and negatively related to domestic sheep numbers in space and time consistent with interspecific competition theory. Although guanacos and domestic sheep have been described as intermediate feeders sharing food resources, no studies have been conducted to compare their diets in sympatric conditions and explore whether the potential exists for direct interspecific competition. We assessed the diet of both species across 9 different sites and 2 seasons by microhistological analysis of fecal samples. We found that (1) guanacos and sheep are generalist herbivores feeding on a wide range of plant species; (2) both are intermediate feeders able to include both monocotyledoneous and dicotyledoneous plants in their diet; (3) both are able to change their diets seasonally; and (4) food niche overlap is high, particularly in summer when food resources are more scarce than in spring. We conclude that the potential for competition between guanacos and sheep is high and could have played a major role in the demise of guanacos. Consequently, current management practices focused on maximizing sheep numbers are not compatible with the recovery of guanaco populations. | ||||
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| Notes | Approved | no | |||
| Call Number | Equine Behaviour @ team @ | Serial | 4253 | ||
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| Author | Galef, J., Bennett G.; Whiskin, E.E. | ||||
| Title | Effects of environmental stability and demonstrator age on social learning of food preferences by young Norway rats | Type | Journal Article | ||
| Year | 2004 | Publication | Animal Behaviour | Abbreviated Journal | Anim. Behav. |
| Volume | 68 | Issue | 4 | Pages |
897-902 |
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| Abstract | We used socially learned food preferences of Norway rats, Rattus norvegicus, to examine two common predictions of formal models of social learning in animals: (1) that animals living in relatively stable environments should be more attentive to socially acquired information than animals living in highly variable environments, and (2) that older demonstrators should have greater influence than younger demonstrators on the behaviour of young observers. Old and young demonstrators were equally effective in modifying the food preferences of juveniles that interacted with them. However, food choices of rats that were moved daily from one cage to another and fed at unpredictable times for unpredictable periods were less affected by demonstrators than were rats maintained in stable environments. Our results thus provided experimental support for the first, but not the second, prediction from theory. | ||||
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| ISSN | 0003-3472 | ISBN | Medium | ||
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| Notes | Approved | no | |||
| Call Number | Equine Behaviour @ team @ | Serial | 5610 | ||
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| Author | Neuringer, A. | ||||
| Title | Reinforced variability in animals and people: implications for adaptive action | Type | Journal Article | ||
| Year | 2004 | Publication | The American Psychologist | Abbreviated Journal | Am Psychol |
| Volume | 59 | Issue | 9 | Pages |
891-906 |
| Keywords | Animals; Behavior, Animal; *Choice Behavior; Conditioning, Operant; Creativeness; Discrimination (Psychology); Humans; Memory; Problem Solving; *Reinforcement (Psychology) | ||||
| Abstract | Although reinforcement often leads to repetitive, even stereotyped responding, that is not a necessary outcome. When it depends on variations, reinforcement results in responding that is diverse, novel, indeed unpredictable, with distributions sometimes approaching those of a random process. This article reviews evidence for the powerful and precise control by reinforcement over behavioral variability, evidence obtained from human and animal-model studies, and implications of such control. For example, reinforcement of variability facilitates learning of complex new responses, aids problem solving, and may contribute to creativity. Depression and autism are characterized by abnormally repetitive behaviors, but individuals afflicted with such psychopathologies can learn to vary their behaviors when reinforced for so doing. And reinforced variability may help to solve a basic puzzle concerning the nature of voluntary action. | ||||
| Address | Department of Psychology, Reed College, Portland, OR 97202, USA. allen.neuringer@reed.edu | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 0003-066X | ISBN | Medium | ||
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| Notes | PMID:15584823 | Approved | no | ||
| Call Number | Equine Behaviour @ team @ | Serial | 4106 | ||
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| Author | DiGian, K.A.; Friedrich, A.M.; Zentall, T.R. | ||||
| Title | Discriminative stimuli that follow a delay have added value for pigeons | Type | Journal Article | ||
| Year | 2004 | Publication | Psychonomic bulletin & review | Abbreviated Journal | Psychon Bull Rev |
| Volume | 11 | Issue | 5 | Pages |
889-895 |
| Keywords | Animals; Behavior, Animal; Choice Behavior; Columbidae; *Cues; *Discrimination (Psychology) | ||||
| Abstract | Clement, Feltus, Kaiser, and Zentall (2000) reported that pigeons prefer discriminative stimuli that require greater effort (more pecks) to obtain over those that require less effort. In the present experiment, we examined two variables associated with this phenomenon. First, we asked whether delay of reinforcement, presumably a relatively aversive event similar to effort, would produce similar effects. Second, we asked whether the stimulus preference produced by a prior relatively aversive event depends on its anticipation. Anticipation of delay was accomplished by signaling its occurrence. Results indicated that delays can produce preferences similar to those produced by increased effort, but only if the delays are signaled. | ||||
| Address | University of Kentucky, Lexington, Kentucky 40506-0044, USA | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 1069-9384 | ISBN | Medium | ||
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| Notes | PMID:15732699 | Approved | no | ||
| Call Number | refbase @ user @ | Serial | 226 | ||
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| Author | Ghirlanda, S.; Vallortigara, G. | ||||
| Title | The evolution of brain lateralization: a game-theoretical analysis of population structure | Type | Journal Article | ||
| Year | 2004 | Publication | Proceedings of the Royal Society of London. Series B: Biological Sciences | Abbreviated Journal | |
| Volume | 271 | Issue | 1541 | Pages |
853-857 |
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| Abstract | In recent years, it has become apparent that behavioural and brain lateralization at the population level is the rule rather than the exception among vertebrates. The study of these phenomena has so far been the province of neurology and neuropsychology. Here, we show how such research can be integrated with evolutionary biology to understand lateralization more fully. In particular, we address the fact that, within a species, left– and right–type individuals often occur in proportions different from one–half (e.g. hand use in humans). The traditional explanations offered for lateralization of brain function (that it may avoid unnecessary duplication of neural circuitry and reduce interference between functions) cannot account for this fact, because increased individual efficiency is unrelated to the alignment of lateralization at the population level. A further puzzle is that such an alignment may even be disadvantageous, as it makes individual behaviour more predictable to other organisms. Here, we show that alignment of the direction of behavioural asymmetries in a population can arise as an evolutionarily stable strategy when individual asymmetrical organisms must coordinate their behaviour with that of other asymmetrical organisms. Brain and behavioural lateralization, as we know it in humans and other vertebrates, may have evolved under basically ‘social’ selection pressures. | ||||
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| Notes | Approved | no | |||
| Call Number | Equine Behaviour @ team @ | Serial | 5345 | ||
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| Author | Paz-y-Miño C. G.; Bond, A.B.; Kamil, A.C.; Balda, R.P. | ||||
| Title | Pinyon jays use transitive inference to predict social dominance | Type | Journal Article | ||
| Year | 2004 | Publication | Nature | Abbreviated Journal | Nature |
| Volume | 430 | Issue | 7001 | Pages |
778-781 |
| Keywords | Animals; Cognition/*physiology; Group Structure; Male; *Social Dominance; Songbirds/*physiology | ||||
| Abstract | Living in large, stable social groups is often considered to favour the evolution of enhanced cognitive abilities, such as recognizing group members, tracking their social status and inferring relationships among them. An individual's place in the social order can be learned through direct interactions with others, but conflicts can be time-consuming and even injurious. Because the number of possible pairwise interactions increases rapidly with group size, members of large social groups will benefit if they can make judgments about relationships on the basis of indirect evidence. Transitive reasoning should therefore be particularly important for social individuals, allowing assessment of relationships from observations of interactions among others. Although a variety of studies have suggested that transitive inference may be used in social settings, the phenomenon has not been demonstrated under controlled conditions in animals. Here we show that highly social pinyon jays (Gymnorhinus cyanocephalus) draw sophisticated inferences about their own dominance status relative to that of strangers that they have observed interacting with known individuals. These results directly demonstrate that animals use transitive inference in social settings and imply that such cognitive capabilities are widespread among social species. | ||||
| Address | Center for Avian Cognition, School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588, USA | ||||
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| Language | English | Summary Language | Original Title | ||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 1476-4687 | ISBN | Medium | ||
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| Notes | PMID:15306809 | Approved | no | ||
| Call Number | refbase @ user @; Equine Behaviour @ team @ room B 3.029 | Serial | 352 | ||
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| Author | Robins, A.; Rogers, L.J. | ||||
| Title | Lateralized prey-catching responses in the cane toad, Bufo marinus: analysis of complex visual stimuli | Type | Journal Article | ||
| Year | 2004 | Publication | Animal Behaviour. | Abbreviated Journal | Anim. Behav. |
| Volume | 68 | Issue | 4 | Pages |
767-775 |
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| Abstract | We tested the responses of Bufo marinus to prey stimuli of varying visual complexity that were moved around the toads in either a clockwise or anticlockwise direction at 1.7 revolutions/min. Predatory responses directed at prey resembling an insect were frequent when the model insect moved clockwise across the visual midline into the right visual hemifield. In contrast, the toads tended to ignore such stimuli when they moved anticlockwise across the midline into the left hemifield. No such lateralization was found when a rectangular strip moved along its longest axis was presented in a similar way. The toads also directed more responses towards the latter stimulus than towards the insect prey. Hence, the results suggest that lateralized predatory responses occur for considered decisions on whether or not to respond to complex insect-like stimuli, but not for decisions on comparatively simple stimuli. We discuss similarities between the lateralized feeding responses of B. marinus and those of avian species, as support for the hypothesis that lateralized brain function in tetrapods may have arisen from a common lateralized ancestor. | ||||
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| ISSN | 0003-3472 | ISBN | Medium | ||
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| Notes | Approved | no | |||
| Call Number | Equine Behaviour @ team @ | Serial | 5365 | ||
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| Author | Fruehwirth, B.; Peham, C.; Scheidl, M.; Schobesberger, H. | ||||
| Title | Evaluation of pressure distribution under an English saddle at walk, trot and canter | Type | Journal Article | ||
| Year | 2004 | Publication | Equine Veterinary Journal | Abbreviated Journal | Equine Vet J |
| Volume | 36 | Issue | 8 | Pages |
754-757 |
| Keywords | Animals; Back/*physiology; Biomechanics; Body Weight/physiology; Exercise Test/veterinary; Gait/*physiology; Horses/*physiology; Humans; Locomotion/*physiology; Pressure | ||||
| Abstract | REASONS FOR PERFORMING STUDY: Basic information about the influence of a rider on the equine back is currently lacking. HYPOTHESIS: That pressure distribution under a saddle is different between the walk, trot and canter. METHODS: Twelve horses without clinical signs of back pain were ridden. At least 6 motion cycles at walk, trot and canter were measured kinematically. Using a saddle pad, the pressure distribution was recorded. The maximum overall force (MOF) and centre of pressure (COP) were calculated. The range of back movement was determined from a marker placed on the withers. RESULTS: MOF and COP showed a consistent time pattern in each gait. MOF was 12.1 +/- 1.2 and 243 +/- 4.6 N/kg at walk and trot, respectively, in the ridden horse. In the unridden horse MOF was 172.7 +/- 11.8 N (walk) and 302.4 +/- 33.9 N (trot). At ridden canter, MOF was 27.2 +/- 4.4 N/kg. The range of motion of the back of the ridden horse was significantly lower compared to the unridden, saddled horse. CONCLUSIONS AND POTENTIAL RELEVANCE: Analyses may help quantitative and objective evaluation of the interaction between rider and horse as mediated through the saddle. The information presented is therefore of importance to riders, saddlers and equine clinicians. With the technique used in this study, style, skill and training level of different riders can be quantified, which would give the opportunity to detect potentially harmful influences and create opportunities for improvement. | ||||
| Address | Movement Science Group, Department V, Clinic of Orthopaedics in Ungulates, University of Veterinary Medicine, Vienna, Austria | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 0425-1644 | ISBN | Medium | ||
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| Notes | PMID:15656510 | Approved | no | ||
| Call Number | Equine Behaviour @ team @ | Serial | 4041 | ||
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| Author | Gardner, A., West, S. A. | ||||
| Title | Cooperation and Punishment, Especially in Humans | Type | Journal Article | ||
| Year | 2004 | Publication | The American Naturalist | Abbreviated Journal | Americ. Natur. |
| Volume | 164 | Issue | 6 | Pages |
753-764 |
| Keywords | kin selection, neighbor-modulated fitness, repression of | ||||
| Abstract | Explaining altruistic cooperation is one of the greatest challenges faced by sociologists, economists, and evolutionary biologists. The problem is determining why an individual would carry out a costly behavior that benefits another. Possible solutions to this problem include kinship, repeated interactions, and policing. Another solution that has recently received much attention is the threat of punishment. However, punishing behavior is often costly for the punisher, and so it is not immediately clear how costly punishment could evolve. We use a direct (neighbor-modulated) fitness approach to analyze when punishment is favored. This methodology reveals that, contrary to previous suggestions, relatedness between interacting individuals is not crucial to explaining cooperation through punishment. In fact, increasing relatedness directly disfavors punishing behavior. Instead, the crucial factor is a positive correlation between the punishment strategy of an individual and the cooperation it receives. This could arise in several ways, such as when facultative adjustment of behavior leads individuals to cooperate more when interacting with individuals who are more likely to punish. More generally, our results provide a clear example of how the fundamental factor driving the evolution of social traits is a correlation between social partners and how this can arise for reasons other than genealogical kinship. |
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| Address | University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, | ||||
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| Notes | Approved | no | |||
| Call Number | refbase @ user @ | Serial | 341 | ||
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