Rise to Power: A Case Study of Male Fecal Androgen and Cortisol Levels before and after a Non-Aggressive Rank Change in a Group of Wild White-Faced Capuchins (Cebus capucinus)

Abstract

We examined fecal androgen and cortisol levels in three adult male white-faced capuchin monkeys (Cebus capucinus) before and after a non-aggressive rank increase in one habituated group residing in the Santa Rosa Sector of the Área de Conservación Guanacaste, Costa Rica. Fecal samples (n = 116) were collected opportunistically between July 2006 and July 2007. Alpha males had higher mean androgen levels than subordinates, and acquisition of the alpha position was linked to an immediate increase in mean androgens. Cortisol levels also increased in the alpha male after acquisition of his new rank, though this increase was delayed relative to the change in rank. These results indicate that, during a non-aggressive rank change, androgen and cortisol levels in male white-faced capuchins are physiological responses to dominance rank, rather than precursors that facilitate rank acquisition.