Most feathers contain only one or two dye-like pigments

Most feathers contain just one or two dye-like pigments.The cardinal's bright red comes from carotenoids,the same pigments that make carrots orange,while the black of its face is from melanin,the pigment that colors our hair and skin.But in bird feathers,melanin isn't simply a dye.It forms hollow nanostructures called melanosomes which can shine in all the colors of the rainbow. To understand how that works,
it helps to remember some things about light.