Melanin-based iridescent feather color in the Jungle Crow.

Sexual differences in Japanese Jungle Crows (Corvus macrorhynchos) are not obvious because both sexes have black plumage. However, closer examination reveals that their plumage color is not only black; it is also iridescent color. Furthermore, the iridescence is more pronounced in adult males than that in females. The iridescence seems to be related to the density and concentration of melanin granules. The density of melanin granule and the concentration of eumelanin in feathers were significantly higher in males than that in females (P<0.01). However, the amount of pheomelanin was below the detection limits in this study.