Plumage colouration and personality in early‐life: sexual differences in signalling

Several studies have shown that melanin‐based traits play a crucial role in social contexts as they are associated with dominance, personality and social behaviour. However, most of these studies have focused on adults, and the role of these traits in juveniles remains scarcely explored. Here, we explore the association between two melanin‐based traits and nestling personality in Common Kestrels Falco tinnunculus. Our results show that female nestlings with blacker plumages displayed bolder personalities, providing evidence of sex‐dependent phenotypic integration of these two traits in males and females. We consider that this differential integration may arise from different selection pressures acting on males and females on plumage colouration during adulthood and that nestling colouration can act as a status signal within the juvenile age‐class.The study was financed by the Spanish Ministerio de Economía y Competitividad (Project: CGL2013-42451-P). DLI is supported by a postdoctoral contract of the REMEDINAL3-CM program of Comunidad Autónoma de Madrid (REF: S2013/MAE-2719)Peer reviewe