Robust autumn social attributes predict spring courtship skills in juvenile female brown-headed cowbirds, Molothrus ater

Abstract

Individuals often show predictable variation in social tendencies over time and across contexts. In species that rely on social interaction for the development of courtship behaviours, predictable variation in juvenile social behaviour may influence the ontogeny of courtship skills by exposing young individuals to different levels of contact with conspecifics. During the autumn and winter, brown-headed cowbirds utilize a social display known as the head-down to facilitate close social interaction with others. In this study we investigated whether head-downs rates are correlated across social contexts, and thus constitute a social temperament trait, and whether variation in head-down rates predicts subsequent courtship behaviour in juvenile cowbirds. During the autumn, we used a fission–fusion perturbation on a flock of juvenile females and males, and recorded the number of approaches and head-downs across social contexts. All individuals were then followed into the breeding season, where we recorded male singing behaviour, female chatter vocalization and consort status. We found that female head-down rates were correlated across contexts during the autumn, and that females that engaged in more head-down displays received more songs from males, responded to more songs with chatter vocalizations and were more likely to be in a consortship during the breeding season. As far as we know, this study presents the first demonstration that a social temperament trait can predict competent adult-like courtship behaviour in juvenile birds, and suggests that juvenile sociability may be an important developmental mechanism in the emergence of reproductive competence. ► We observed a flock of juvenile brown-headed cowbirds during autumn and spring of their first year. ► In autumn, we performed a fission–fusion flock perturbation to examine social behaviour across contexts. ► Females showed correlated rates of affiliative head-down displays across social contexts in autumn. ► Autumn head-down rates predicted spring courtship skills in females. ► Individual social attributes may shape the development of courtship skills in female birds.