Plumage colour predicts dispersal propensity in male pied flycatchers

Melanin-based colouration of tegument structures may be related to variability in the expression of certain strategies or behaviours within a species, including the propensity to disperse. This is because melanin synthesis may be physiologically linked to certain behaviours and personality traits, as proposed by the hypothesis of the pleiotropy in the melanocortin system (HPMS). During a 28-year period (1988–2015), we studied the melanin-based dorsal colouration of male pied flycatchers (Ficedula hypoleuca) in relation to natal dispersal movements between contrasting (pine and oak) habitats. In addition, the relationship between tonic immobility (TI), a measure of individual fearfulness towards predators, and plumage colour was examined using a shorter time series. Consistent with HPMS, males’ dispersal propensity was related to their plumage colour, with the blackest individuals being more likely to disperse into a new habitat to breed. Blacker males remained for longer in TI than lighter ones. The positive relationship between plumage melanisation and TI might result from the pleiotropic effect of the melanocortin system on glucocorticoid-mediated stress and fearfulness responses as well as on eumelanin synthesis. This study provides solid empirical support for the HPMS in relation to natal dispersal behaviour.Long-term monitoring of the study population has been mainly funded by the Spanish CCYT, most recently by projects CGL2014-55969-P (to F. Valera) and CGL201570639-P (to L.Z. Garamszegi) of the Spanish Ministry of Economy and Competitiveness. CC received financial support from the Spanish Ministry of Economy and Competitiveness (SVP-2013-067686). LP-R was supported by a postdoctoral contract from MINECO through the Severo Ochoa Programme for Centres of Excellence in RandDandI (SEV-2012-0262). DC was supported by projects CGL2009-10652 and CGL2015-70639-P.Peer reviewe