The physics of structural plumage colours in birds
A look at the physics that underlie how birds grow coloured plumages, especially violet, blue and white feathers
Hyacinth Macaw, Anodorhynchus hyacinthinus. (Credit: Randy / Creative Commons Attribution 2.0 Generic license.)
Most avian plumage colours are the result of different types of pigments that are deposited into feathers while they are regrowing after moult. However, pigments alone do not produce all avian feather colors. Blues, such as those seen in hyacinth macaws, Anodorhynchus hyacinthinus, and white, such as the snowy colour of Bali mynahs, Leucopsar rothschildi, typically result from small changes in feather structure that alters their light reflective properties. These fundamental modifications cause violet and blue light to be selectively reflected from the feather surface in the case of violet/blue feathers, while white feathers reflect all visible light. In short, violets, blues and whites are structural colors, or schemochromes.
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