Do female rhesus macaques choose novel males?

Prior research has shown that estrous female rhesus macaques (Macaca mulatto) maintain spatial proximity preferentially to lower-ranking males. In this paper, 657 h of focal individual follows of 48 free-ranging estrous female rhesus macaques of two social groups during two mating seasons are used to evaluate the hypothesis that this phenomenon is attributable to female mate choice for novel males. This hypothesis is plausible because of the positive correlation between dominance rank and the length of time since a male immigrated into a group or matured in his natal group (i.e., his breeding tenure). However, partial correlation analysis showed that after removing the effect of dominance rank, there was no significant tendency for estrous females to maintain proximity preferentially to males of shorter breeding tenure. In contrast, removing the effect of breeding tenure did not eliminate the result that estrous females maintained proximity preferentially to lower ranking males. Novel (i.e., extra-group, new immigrant, and newly matured natal) males did not consistently experience more estrous female proximity maintenance than non-novel males, although sample sizes are too small to conclusively falsify this hypothesis. Within male-estrous female dyads, responsibility for proximity maintenance did not tend to shift from the female to the male between consecutive mating seasons. Male breeding tenure was not significantly correlated with year-to-year change in responsibility for proximity maintenance. Male breeding tenure was not consistently correlated with female sexual refusal. In one of two social groups, in one of two mating seasons, females appeared to choose novel males. These data provide, at most, weak support for the hypothesis that female primates in multi-male groups exercise mate choice for novel males. © 1995 Wiley-Liss, Inc.