SOCIAL DYNAMICS AND THE CORTISOL RESPONSE TO IMMOBILIZATION STRESS OFTHE AFRICAN WILD DOG, LYCAON-PICTUS

The aims of the study were to characterize the cortisol response to im mobilization stress in African wild dogs (Lycaon pictus) and to invest igate the relationship between stress and sociality in these pack-livi ng canids. Ad lib. observations were made on a captive pack of 19 wild dogs. Individuals were classified as either dominant or subordinate. Cardinal and ordinal dominance indices were also calculated for pack m embers, as were three other behavioral indices. Active and passive dom inance styles were distinguished. Serial blood samples were drawn from animals after chemical immobilization and again after ACTH challenge. The relationship among rank, plasma cortisol concentration, and behav ioral style was investigated. When data were combined over the entire study period, there was no obvious relationship between rank and corti sol concentrations or cortisol responsiveness to immobilization stress . Instead, younger animals had higher cortisol concentrations than old er ones. Age cohorts were also clearly separated on the basis of behav ioral profiles. For males, these distinctions among age classes were e specially apparent during the second part of the study period, when su badults occupied dominant positions in the hierarchy. Adult males main tained relatively low cortisol concentrations, despite being involved in and losing a high proportion of dominance interactions. Age-related differences in cortisol profiles of dominant individuals may be expla ined by differences in the style of dominance employed, with younger m ales using proportionately more active dominance (threats used to elic it submission). The separation of age classes according to rank, behav ioral styles, and cortisol concentrations may reflect improved social skillfulness with age. (C) 1997 Academic Press.