Primate copulation calls and postcopulatory female choice

Females in some species of Old World monkeys and apes vocalize after copulation, but the function of these vocalizations is not clear. In this article, we examine the hypothesis that copulation calls are a form of postcopulatory female choice. According to this hypothesis, copulation calls are honest signals of fertility (i.e., ovulation) that are used by females to encourage mate guarding by their preferred mating partners and reduce the likelihood of sperm competition. Evidence in favor of this hypothesis is reviewed and discussed in relation to other hypotheses. We suggest that the evolution of female copulation calls in primates is linked to the evolution of other female mating signals such as exaggerated sexual swellings, the potential for sperm competition, and the opportunity for precopulatory female mate choice.