Plumage colouration variability of male Bluethroats (Luscinia svecica cyanecula) wintering in SE Iberia

Abstract

Male colouration has a key role in signalling individual quality during the breeding season. Although winter plumage probably correlates with summer plumage, few studies have focused on the determinants of male colouration during the non-breeding period. If plumage colouration is related to an individual’s age or is strongly correlated with body condition during the non-breeding period, this trait could be used by conspecifics to assess quality, origin or status of a given individual.Here,we analysed plumage colouration and body size of male Bluethroats (Luscinia svecica cyanecula) wintering in SE Iberia. We found that young individuals had narrower black bands and wider white bands than adult individuals in their throat patch.Also, thewidth of the chestnut band increased with later capture date. Finally, blue throat colouration was positively correlated with tail length and negatively correlatedwith tarsus length.We could not find any significant relationship between throat patch colouration and bodymass.We concluded that individual’s age and capture date were significantly related to black and chestnut throat colouration, respectively. Therefore, these coloured bands could provide reliable cues on individual’s age and their geographical origins. The variability of plumage colouration of wintering Bluethroats provides an excellent study system in which to test further hypotheses on the role of the throat patch colouration outside the breeding season.