Kingfisher Feathers Look Blue — But They Contain No Pigment

My human eye is fascinated by iridescent colours — butterflies, scarab beetles, and of course birds, like some species of Kingfisher. Imagine my surprise when, today, I learned that the bright, sparkling blue feathers of Kingfishers have no pigment in them at all (yes, truly). But, rather, the beautiful and particular shade of blue is created through the structural arrangement of the transparent material that makes up the blue parts of their plumage! So, what we see as blue has nothing to do with pigment and everything to do with nano structures that optimise reflection of that type of blue light. And there's more: the way in which these structures are layered and aligned (or non-aligned) contributes to what we experience, visually, as full or partial iridescence. You can read a more scientific and detailed explanation, including slides of the nano structures, at this brilliant entry, under Cambridge University's Animal Alphabet series.