Dominance, cortisol, and behavior in small groups of female cynomolgus monkeys (Macaca fascicularis)

The relationships among social rank, basal cortisol concentrations, and soc ial behavior were assessed in adult female cynomolgus monkeys (Macaca fasci cularis). Subjects were 157 unrelated, reproductively intact animals housed in 30 small groups. Rank determinations were made monthly. Blood samples w ere collected on two occasions, 4.5 and 7.5 months following initial group formation. Regular behavioral observations were conducted on a subset of an imals over a period of 4 weeks, 9 months following group formation. Analyse s revealed that serum cortisol values were significantly correlated across the two sampling periods, with no significant change in absolute values. Wh ile social rank was positively correlated across both samples, there was no relationship between rank and cortisol. However, dominant and subordinate animals did differ in the rates of performance of aggressive and submissive behaviors. These data suggest that social rank does not influence baseline serum cortisol in adult female cynomolgus monkeys, despite stability in me asures of rank and cortisol and the presence of the usual behavioral differ ences between dominants and subordinates. (C) 2001 Academic Press.