Wey, T., Blumstein, D. T., Shen, W., & Jordán, F. (2008). Social network analysis of animal behaviour: a promising tool for the study of sociality. Anim. Behav., 75(2), 333–344.
Abstract: Social animals live and interact together, forming complex relationships and social structure. These relationships can have important fitness consequences, but most studies do not explicitly measure those relationships. An approach that explicitly measures relationships will further our understanding of social complexity and the consequences of both direct and indirect interactions. Social network analysis is the study of social groups as networks of nodes connected by social ties. This approach examines individuals and groups in the context of relationships between group members. Application of social network analysis to animal behaviour can advance the field by identifying and quantifying specific attributes of social relationships, many of which are not captured by more common measures of sociality, such as group size. Sophisticated methods for network construction and analysis exist in other fields, but until recently, have seen relatively little application to animal systems. We present a brief history of social network analysis, a description of basic concepts and previous applications to animal behaviour. We then highlight relevance and constraints of some network measures, including results from an original study of the effect of sampling on network parameter estimates, and we end with promising directions for research. By doing so, we provide a prospective overview of social network analysis' general utility for the study of animal social behaviour.
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Westlin-van Aarde, L. M., van Aarde, R. J., & Skinner, J. D. (1988). Reproduction in female Hartmann's zebra. J Reprod Fert, 84, 505–511.
Abstract: Ovaries, fetuses and plasma were collected from zebra mares shot in the Etosha National Park in Namibia between 15 and 25 August 1983. Ovarian weight was affected by reproductive status and most of the non-pregnant mares were anoestrous. The number of follicles varied between individuals and only pro-oestrous/oestrous mares had follicles larger than 20 mm in diameter. The largest follicle in pregnant mares was only 9 mm in diameter. Corpora lutea and corpora albicantia were found in non-pregnant as well as pregnant mares: 4 pregnant mares had only corpora albicantia. The presence of secondary corpora lutea could not be confirmed in any of the pregnant mares. Implantation was estimated to occur at around 73 days of gestation, and most mares (84%) had conceived between November and April. Peripheral concentrations of plasma progesterone during pregnancy varied from 0·5 to 2·4 ng/ml.
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Western D,. (1975). Water availability and its influence on the structure and dynamics of a savannah large mammal community. E Afr Wildl J 1, 3, 265–288.
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Westermann, K. (2012). The contribution of horses (Equus caballus) to human health Requirements, stresses and strains, selection, training, compensation and rectification. In K. Krueger (Ed.), Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: For a longer time, I occupy myself in my profession as a veterinarian, with the requirements and strains of horses (Equus caballus) used to contribute human health. For the first time complex and interdisciplinary scientific investigations are made to draw conclusions from determined requirements and strains of so-called therapy horses in regard to an adequate selection and training as well as compensation of physical and psychic strains and rectification of these horses. Focusing the physical and psychic resources of horses as well, it becomes obvious, that a horse which received conventional training, compensation and rectification is neither adequately prepared for its task as a therapy horse, nor adequately escorted through its employment. Therefore it is time now for hippologists and veterinarians to promote a justifiable use of horses for therapy purposes by suitable means having in mind not only the efficiency of the intervention, but also the safety of clients, therapists and horses as well as our responsibility towards the horse and animal welfare in general. For a concept profitable for all participants, different, each other complementing modules are worked out. Based on an interdisciplinary exchange of know-how and interdisciplinary cooperation, the decisive elements of a comprehensive, targeted, requirement-oriented and horse-friendly training, compensation of the horses strains and rectification are outlined.
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Westermann, K. (2012). Das Therapiepferd: Was macht es so besonders und wertvoll? In K. Krueger (Ed.), Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: Als Tierärztin beschäftige ich mich seit geraumer Zeit mit den Anforderungen und Belastungsmomenten von Therapiepferden. Mein Ziel ist es, geeignete Methoden für die Auswahl, Ausbildung, Ausgleichs- und Korrekturarbeit dieser Pferde zu entwickeln.
Umfangreiche Recherchen haben ergeben, dass ein Pferd unter Berücksichtigung seiner physischen und psychischen Fähigkeiten durch die derzeit verbreitete Ausbildung, Ausgleichs- und Korrekturarbeit nur unzureichend auf die Aufgaben eines Therapiepferdes vorbereitet bzw. während seinesEinsatzes begleitet wird.
Aber genau hier liegt der Schlüssel für die Sicherheit von Klient, Therapeut und Pferd und den Erfolg der Therapie- und Fördermaßnahme. Darüber hinaus ist es auch im Sinne der Verantwortung für das Pferd und des Tierschutzes an der Zeit, durch geeignete Maßnahmen die verantwortbare Nutzung des Pferdes als Therapiepferd zu unterstützten.
Auf der Basis von interdisziplinärem Wissenstransfer und interinterdisziplinärer Kooperation werden die entscheidenden Elemente einer nachvollziehbaren, zielorientierten, bedarfs- und pferdegerechten Ausbildung, Ausgleichs- und Korrekturarbeit von Therapiepferden kurz skizziert.
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Westergaard, G. C., Suomi, S. J., & Higley, J. D. (2002). Handedness is associated with immune functioning and behavioural reactivity in rhesus macaques. Laterality, 7(4), 359–369.
Abstract: In the present study we examined the relationship among handedness, immune functioning, and behavioural reactivity in rhesus macaques. We used the absolute number of CD4+ (T-helper) and CD8+ (T-suppressor) cells as dependent measures of immune functioning. We derived reactivity profiles from behavioural responses to a threat, and hand preference profiles from a quadrupedal food-reaching test. The results indicate positive correlations between the frequency of right versus left hand reaches and the absolute number of CD4+ cells, and between the frequency of right versus left hand reaches and the degree of human-directed aggression in response to an invasive threat. Immune measures were not associated with the strength of hand preference. These results are consistent with and extend previous findings obtained with rodents to nonhuman primates and provide further support for the view that behavioural lateralisation is associated with immune functioning and behavioural reactivity.
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Westergaard, G. C., Liv, C., Rocca, A. M., Cleveland, A., & Suomi, S. J. (2004). Tufted capuchins (Cebus apella) attribute value to foods and tools during voluntary exchanges with humans. Anim. Cogn., 7(1), 19–24.
Abstract: This research examined exchange and value attribution in tufted capuchin monkeys ( Cebus apella). We presented subjects with opportunities to obtain various foods and a tool from an experimenter in exchange for the foods or tool in the subjects' possession. The times elapsed before the first chow biscuits were expelled and/or an exchange took place were recorded as the dependent measures. Laboratory chow biscuits, grapes, apples, and a metal bolt (a tool used to probe for syrup) were used as experimental stimuli. The subjects demonstrated the ability to recognize that exchanges could occur when an experimenter was present with a desirable food. Results indicate that subjects exhibited significant variation in their willingness to barter based upon the types of foods that were both in their possession and presented by the experimenter. Subjects more readily traded chow biscuits for fruit, and more readily traded apples for grapes than grapes for apples. During the exchange of tools and food, the subjects preferred the following in descending order when the probing apparatus was baited with sweet syrup: grapes, metal bolts, and chow biscuits. However when the apparatus was not baited, the values changed to the following in descending order: grapes, chow, and metal bolts. These results indicate that tufted capuchins recognize opportunities to exchange and engage in a simple barter system whereby low-valued foods are readily traded for more highly valued food. Furthermore, these capuchins demonstrate that their value for a tool changes depending upon its utility.
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Westergaard, G. C., Liv, C., Chavanne, T. J., & Suomi, S. J. (1998). Token-mediated tool-use by a tufted capuchin monkey (Cebus apella). Anim. Cogn., 1(2), 101–106.
Abstract: This research examined token-mediated tool-use in a tufted capuchin monkey (Cebus apella). We conducted five experiments. In experiment 1 we examined the use of plastic color-coded chips to request food, and in experiments 2-5 we examined the use of color-coded chips to request tools. Our subject learned to use chips to request tools following the same general pattern seen in great apes performing analogous tasks, that is, initial discrimination followed by an understanding of the relationship among tokens, tools, and their functions. Our findings are consistent with the view that parallel representational processes underlie the tool-related behavior of capuchins and great apes.
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Westergaard, G. C., Evans, T. A., & Howell, S. (2007). Token mediated tool exchange between tufted capuchin monkeys (Cebus apella). Anim. Cogn., .
Abstract: Three experiments were conducted to test whether a pair of tufted capuchin monkeys (Cebus apella) could generalize their ability to exchange tokens and tool objects with a human experimenter to similar exchanges with a conspecific partner. Monkeys were tested in side-by-side enclosures, one enclosure containing a tool-use apparatus and one or more token(s), and the other enclosure containing one or more tool object(s). The monkeys willingly transferred tokens and tools to a conspecific with little practice. Following a small amount of training, we also found that the monkeys would select situation-appropriate tokens to exchange for specific tools, but did not select appropriate tool objects in response to another monkey's token transfers. Implications regarding role reversal are discussed.
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Westergaard, G. C. (1999). Structural analysis of tool-use by tufted capuchins (Cebus apella) and chimpanzees (Pan troglodytes). Anim. Cogn., 2(3), 141–145.
Abstract: Using Matsuzawa's hierarchical system of classification, I compared tool-use patterns of tufted capuchins (Cebus apella) to those of chimpanzees (Pan troglodytes). The results indicated that wild C. apella exhibit fewer and less complex tool-use patterns than do captive C. apella and wild and captive P. troglodytes. Although most patterns of tool-use observed among P. troglodytes occur in captive C. apella, there are some notable exceptions, including tool-use in communicative contexts and the use ¶of three-tool combinations. I conclude that C. apella are unique among monkeys in their demonstrated propensities for higher-order combinatorial behavior and are likely capable of using symbolic combinations, although not at the level of complexity that has been demonstrated in ¶P. troglodytes.
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