Predation favours cryptic coloration in breeding male pied flycatchers

Abstract

Male pied flycatchers, Ficedula hypoleuca, are highly variable in breeding plumage coloration, ranging from bright (black-and-white) to dull (brown and female-like). Male disappearance was studied during the breeding season in a woodland area in Norway. The disappearance peaked during the nestling period, probably because of predation by the European sparrowhawk, Accipiter nisus. Significantly more bright (11%) than dull (0%) males disappeared during breeding. Variation in male body size (wing length, body mass), age, previous breeding experience, and aspects of behaviour (effort and success in mate attraction and in feeding of the young) did not seem to explain the differences in male disappearance. Hence, the data suggest a cost associated with conspicuous coloration. Brightly coloured males may be more readily detected than dull males by a predator and detected earlier, resulting in a greater chance of a successful attack. Female disappearance (10%) was similar to that of brightly coloured males but significantly higher than that of dull males. Females may be initially less easily detected but once detected less able to escape a predator. The results support the view that predation may help explain sexual dimorphism in bird coloration, delayed plumage maturation, and why males in species with less male parental care are more colourful than males in species with more male parental care.