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Flauger, B., Krueger, K., Gerhards, H., & Moestl, E. (2009). Measurement of glucocorticoid metabolites in horse faeces: the validation of different group specific enzymeimmunoassays and extraction methods. In S. Cremer, A. Schrempf, & J. Heinze (Eds.), Proceeding of the 102. Annual meeting of the Deutsche Zoologische Gesellschaft (DZG). (166). München: Dt. Zoologische Ges.
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van Duyne, C., Ras, E., de Vos, A. E. W., de Boer, W. F., Henkens, R. J. H. G., & Usukhjargal, D. (2009). Wolf Predation Among Reintroduced Przewalski Horses in Hustai National Park, Mongolia. Journal of Wildlife Management, 73(6), 836–843.
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Shettleworth, S. J. (2009). The evolution of comparative cognition: is the snark still a Boojum? Behav Processes, 80.
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von Bayern, A. M. P. (2009). The role of experience in problem solving and innovative tool use in crows. Curr Biol, 19.
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Reader, S. M., & Laland, K. N. (2009). Animal Innovation. Oxford: Oxford University Press.
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Veen, P., Jefferson, R., de Smidt, J., & van der Straaten, J. (2009). Grasslands in Europe of high nature value. The Netherlands: Brill.
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Ruid, D. B., Paul, W. J., Roell, B. J., Wydeven, A. P., Willging, R. C., Jurewicz, R. L., et al. (2009). Wolf-Human Conflicts and Management in Minnesota, Wisconsin, and Michigan. In A. P. Wydeven, T. R. Van Deelen, & E. J. Heske (Eds.), Recovery of Gray Wolves in the Great Lakes Region of the United States: An Endangered Species Success Story (pp. 279–295). New York, NY: Springer New York.
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Puga-Gonzalez, I., Hildenbrandt, H., & Hemelrijk, C. K. (2009). Emergent Patterns of Social Affiliation in Primates, a Model. PLoS Comput Biol, 5(12), e1000630.
Abstract: Author Summary
<p>Individual primates distribute their affiliative behaviour (such as grooming) in complex patterns among their group members. For instance, they reciprocate grooming, direct it more to partners the higher the partner's rank, use it to reconcile fights and do so in particular with partners that are more valuable. For several types of patterns (such as reconciliation and exchange), a separate theory based on specific cognitive processes has been developed (such as individual recordkeeping, a tendency to exchange, selective attraction to the former opponent, and estimation of the value of a relationship). It is difficult to imagine how these separate theories can all be integrated scientifically and how these processes can be combined in the animal's mind. To solve this problem, we first surveyed the empirical patterns and then we developed an individual-based model (called GrooFiWorld) in which individuals group, compete and groom. The grooming rule is based on grooming out of fear of defeat and on the anxiety reducing effects of grooming. We show that in this context this rule alone can explain many of the patterns of affiliation as well as the differences between egalitarian and despotic species. Our model can be used as a null model to increase our understanding of affiliative patterns of primates.</p>
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Hausberger, M., Gautier, E., Biquand, V., Lunel, C., & Jégo, P. (2009). Could Work Be a Source of Behavioural Disorders? A Study in Horses. PLoS ONE, 4(10), e7625 EP -.
Abstract: <p>Stress at work, as shown by a number of human studies, may lead to a variety of negative and durable effects, such as impaired psychological functioning (anxiety, depression…). Horses share with humans this characteristic of working on a daily basis and are submitted then to work stressors related to physical constraints and/or more “psychological” conflicts, such as potential controversial orders from the riders or the requirement to suppress emotions. On another hand, horses may perform abnormal repetitive behaviour (“stereotypies”) in response to adverse life conditions. In the present study, we investigated whether the type of work the horses are used for may have an impact on their tendency to show stereotypic behaviour (and its type) outside work. Observations in their box of 76 horses all living in the same conditions, belonging to one breed and one sex, revealed that the prevalence and types of stereotypies performed strongly depended upon the type of work they were used for. The stereotypies observed involved mostly mouth movements and head tossing/nodding. Work constraints probably added to unfavourable living conditions, favouring the emergence of chronic abnormal behaviours. This is especially remarkable as the 23 hours spent in the box were influenced by the one hour work performed every day. To our knowledge, this is the first evidence of potential effects of work stressors on the emergence of abnormal behaviours in an animal species. It raises an important line of thought on the chronic impact of the work situation on the daily life of individuals.</p>
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Bourjade, M., de Boyer des Roches, A., & Hausberger, M. (2009). Adult-Young Ratio, a Major Factor Regulating Social Behaviour of Young: A Horse Study. PLoS ONE, 4(3), e4888.
Abstract: <sec> <title>Background</title> <p>Adults play an important role in regulating the social behaviour of young individuals. However, a few pioneer studies suggest that, more than the mere presence of adults, their proportions in social groups affect the social development of young. Here, we hypothesized that aggression rates and social cohesion were correlated to adult-young ratios. Our biological model was naturally-formed groups of Przewalski horses, <italic>Equus f. przewalskii</italic>, varying in composition.</p> </sec><sec> <title>Methodology/Principal Findings</title> <p>We investigated the social interactions and spatial relationships of 12 one- and two-year-old Przewalski horses belonging to five families with adult-young ratios (AYR) ranging from 0.67 to 1.33. We found striking variations of aggression rates and spatial relationships related to the adult-young ratio: the lower this ratio, the more the young were aggressive, the more young and adults segregated and the tighter the young bonded to other young.</p> </sec><sec> <title>Conclusion/Significance</title> <p>This is the first study demonstrating a correlation between adult-young ratios and aggression rates and social cohesion of young individuals in a naturalistic setting. The increase of aggression and the emergence of social segregation in groups with lower proportions of adults could reflect a related decrease of the influence of adults as regulators of the behaviour of young. This social regulation has both theoretical and practical implications for understanding the modalities of the influence of adults during ontogeny and for recommending optimal settings, as for instance, for schooling or animal group management.</p> </sec>
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