| Summary: | The goal of this study was to evaluate the impact of sociogenic stress (more specifically, aggression-mediated stress) in a large pack of captive timber wolves (Canis lupus). Urine contaminated snow was collected for three consecutive winters (from early December to the end of March) encompassing the mating seasons (January to mid-March). Audio-video recording of behaviour, with a focus on agonistic behaviour, was performed during the same time period. Urine samples were assayed for Creatinine (Cr), Cortisol (C) and Testosterone (T). The frequency and intensity of intra- and inter-sexual dyadic agonistic interactions were scored for both initiators and recipients. The data were examined for sex differences, for annual differences, and for individual differences in relation to rank and status in the pack. C:Cr ratios were higher in beta and omega animals as were the T:Cr ratios in some of the same animals. The associations between hormonal levels, aggressive behaviours, and weather parameters were shown to vary from one breeding season to the next. There was an increase in pack C:Cr levels over the three years of this study. Weather was an unlikely factor in the rise of cortisol across seasons. Historically, models of social stress as a regulator of group size have been based on studies conducted with rodents and have predicted higher glucocorticoid levels and lower androgen levels among low-ranking animals. Consistent with recent models of more social species in general, and of cooperative breeders specifically, the patterns here suggest an alternative trend. The data also suggest that behavioural-physiological mechanisms of reproductive suppression in subordinates by dominant individuals may not be as crucial as are purely behavioural strategies. The data are discussed in the context of recent socioendocrinological theories of social stress and reproductive suppression in the literature on Primates and Carnivores. Thesis (Ph.D.)--Dalhousie University (Canada), 2002.
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