Mechanisms of Feather Structural Coloration and Pattern Formation in Birds

Many bird species have microstructures that produce diverse feather colors. The morphology of these color-generating microstructures differs largely depending on the avian species. We classified the structural coloration of bird feathers into three types: thin-layer interference, melanin granules, and amorphous networks, and provide examples for each in avian coloration mechanisms. Bird body colors and patterns can depend on the body part, age, sex, and season; however, body patterns and each feather color combination are essentially determined in the feather bud during the feather developmental process. Although birds do not have the colorful erythrophore, xanthophore, and iridophore cells found in lower vertebrates, they obtain dietary pigments from foods and have structural colors within their feathers. With these colorations, feathers in birds often show amazing complex patterns and the diversity of their body colors and patterns are characteristics is very important for their living strategy.