Environmental and social correlates of the plumage color polymorphism in an urban dweller, feral pigeon (Columba livia f. domestica)

We examined how urban environments affect the abundance, proportion, and diversity of plumage color morphs in feral pigeons. Five major plumage color morphs (black, blue, white, red, and mixed) were counted in sixty 25-ha plots in Poznań City (Poland). Generalized additive models were used to study the correlations among abundance, proportion of morphs, and environmental factors. Anthropogenic food sources were positively correlated with the abundance of black morphs and the proportions of black and red morphs. The blue morph abundance peaked at a moderate percentage of tall building cover, but its proportion decreased. A similar decrease was observed in the mixed plumage morphs. The abundance of blue morphs decreased, whereas the abundance of white morphs and the proportion of red morphs increased as the distance from the city center increased. The plumage color morph diversity (Simpson) index was positively correlated with food sources and hedgerow density but negatively correlated with street density. Color morph diversity in the study area may be sustained by differential responses of morphs to the environmental features of the urban environment. However, the positive correlation between the abundance of morphs indicates social attraction rather than social isolation among plumage color morphs.