A cry for help: female distress calling during copulation is context dependent

Abstract

Owing to selection for increased mating propensity, males often expose females to sexual harassment. Consequently, females may evolve counterstrategies to retain control of mating. Females can do this directly by resisting copulations, or indirectly by manipulating other males to intervene and prevent the copulation. Uttering copulation calls may be one indirect method for females to trigger male intervention. Copulation calls are commonly observed in mammals, primarily in primates, and also in some birds. Female fowl, Gallus gallus, sometimes utter calls during copulation, particularly in forced copulations with low-ranking males. These loud calls, called distress calls, attract other males and can result in disruption of the copulation, and subsequent mating with the intervening male if he is high ranking. Consequently, uttering such calls can act both to abort a coerced copulation and to generate novel opportunities for females to copulate with higher-ranking males. Nevertheless, uttering loud calls can carry costs, such as attracting predators. Females are therefore predicted to utter copulation calls primarily when doing so offers benefits, which for female fowl requires the presence of another high-ranking male. We tested this prediction by altering the social environment of female domestic fowl, G. g. domesticus. We found that females uttered copulation calls more frequently during copulations in the presence of dominant ‘observer’ males than in their absence. Thus, we provide evidence of context-dependent utterance of female calls during copulations in a bird. This type of female vocalization is rarely investigated in nonprimate vertebrates, but increased research in this field offers potential to improve understanding of female mate choice strategies and the dynamics of sexual selection.