Alarm calling best predicts mating and reproductive success in ornamented male fowl, Gallus gallus

Studies of female mate choice in fowl typically invoke ornament size as the best predictor of male reproductive success. The strongest evidence comes from experiments in which a hen is presented with two unfamiliar and physically separated males that she can evaluate and mate with for up to 120 min. This design controls for prior experience and male–male competition, but deprives females of information available only from longer sampling periods and a more natural context. In the wild, fowl spend their lives in stable social groups. We observed birds under naturalistic conditions to evaluate the biological significance of ornament size and to explore other potential predictors of male mating and reproductive success. For each male, we measured morphology and several behaviours related to food, predators, dominance and courtship. Using principal components analysis and multiple regression, we show that behaviour is the best predictor of male mating and reproductive success under natural conditions, and that the most salient behaviours are dominance and the rate of antipredator signalling. Dominance probably affects an individual's reproductive success by determining access to receptive females, but the mechanism responsible for the role of alarm calling is less clear. Costly alarm signals may advertise male quality, or they may reflect judicious risk-taking by males that have achieved mating success.