Melanin is the main pigment in animal coloration and considerable variation in the concentrations of the two melanin forms (pheo- and eumlanin) in pigmented tissues exists among populations and individuals. Melanin-based coloration is receiving increasing attention particularly in socio-sexual communication contexts because the melanocortin system has been hypothesized to provide a mechanistic basis for covariation between coloration and fitness traits. However, with few notable exceptions, little detailed information is available on inter-individual and inter-population variation in melanin pigmentation and on its environmental, genetic and ontogenetic components. Here, we investigate melanin-based coloration in an Italian population of a passerine bird, the barn swallow (Hirundo rustica rustica), its sex- and age-related variation, and heritability. The concentrations of eu- and pheomelanin in the throat (brown) and belly (white-to-brownish) feathers differed between sexes but not according to age. The relative concentration of either melanin (Pheo:Eu) differed between sexes in throat but not in belly feathers, and the concentrations in males compared to females were larger in belly than in throat feathers. There were weak correlations between the concentrations of melanins within as well as among plumage regions. Coloration of belly feathers was predicted by the concentration of both melanins whereas coloration of throat feathers was only predicted by pheomelanin in females. In addition, Pheo:Eu predicted coloration of throat feathers in females and that of belly feathers in males. Finally, we found high heritability of color of throat feathers. Melanization was found to differ from that recorded in Hirundo rustica rustica from Scotland or from H. r. erythrogaster from North America. Hence, present results show that pigmentation strategies vary in a complex manner according to sex and plumage region, and also among geographical populations, potentially reflecting adaptation to different natural and sexual selection regimes, and that some coloration components seem to be highly heritable.

We studied the three main components of trophic niches in the richest assemblages of breeding gulls and terns in Italy (8 species) that typify the communities of the large deltas of Mediterranean Europe. Each species feeds mainly on fish, except for the gull‐billed tern that feeds essentially on terrestrial vertebrates. Other prey contributed slightly to the energy balance, although small invertebrates prevailed numerically in the diets of the Mediterranean and black‐headed gulls. The seabirds cumulatively consumed a variety of fish, in frequencies that closely reflected the latter's abundance. Selection of fish species by each seabird were strongly determined by the bird's foraging habitat, and not by any preference for particular prey. The size of the prey was related to the size of the seabird. The diurnal rhythms of feeding activity were uniform, and the time component did not contribute to niche segregation. Dietary patterns suggest that within the overall space of their niches, the seabirds select trophic resources mainly through preferences for specific types of foraging habitats with their associated prey types. In the selected habitats, various prey types are exploited in relation to availability, and prey is selected on the basis of size. Although it is well known that interspecific competition is not proportional to the overlap in resource use, in our community of seabirds evidence that competition promotes niche segregation comes from the observation that overlap in the foraging and feeding niches are clearly complementary, and that the foraging niches and the preferred prey size seem to be regularly rather than randomly spaced. We suggest that the seabirds segregate their trophic niches by selecting different macro‐habitats, while their overlap in food is high, thus confirming earlier reports that habitat is more important than food in the segregation of trophic niches.