Few birds are as stunning as the brilliantly iridescent hummingbirds. These brilliant colors that hummingbirds seemingly turn on and off at will are not colors made from pigments as are the colors of paint and ink. And the birds don’t turn them on and off at will, they have no control over the brilliant flashes that we see.
While most birds’ get the color of their feathers from pigmentation, the hummingbird’s shimmering colors are formed by the structure of their feathers. Light hits layers of special prism-like cells, or diffraction gratings, within the top layers of the feathers and is broken apart; some wavelengths are reinforced and intensified, while others are nullified through interference. The resulting colors can be seen only when the light is hitting the feathers at precisely the right angle.
Interference coloration is responsible for the colors we see at the edges of oil films floating on water and in the skin of soap-bubbles – the specific color shifts when the angle of light falling on the refractive material shifts. This is why the iridescent colors on a hummingbird’s neck will shift suddenly from ruby red to brilliant blue and vivid green and then just as suddenly turn black or dark brown as the hummingbird turns it head.
These two images of this male Anna’s Hummingbird were taken less than a second apart, in the first the sun was refracted,
in the second the bird shifted just a fraction and we see the natural, un-refracted matte black pigment color of the melanin in the bird’s feathers.
Iridescent hummingbird colors actually result from a combination of refraction and pigmentation, since the diffraction structures themselves are made of melanin.
Each platelet can produce different colors according to the angle at which it is viewed. Thus, a gorget, the brilliantly colored ‘bib’ at a male hummingbird’s throat, may be ruby red when seen from one angle, but as the angle changes the gorget shifts color. Thus, a hummingbird can shift its position just a little, and what was once dull black or dark brown will become a blazing spectrum.
No other bird has such a wide spectrum of brilliant iridescent colors as do hummingbirds. Of course it is only the males that flash iridescent, female, though attractive are pale in comparison,
The hummingbird’s wing is colorless and nearly transparent
Not all melanin in hummingbirds is the same. For example the melanin in Allen’s and Rufous Hummingbirds’ pigmentation is slightly different and looks rusty brown instead of black.
Female Anna’s Hummingbird gathering nectar from a treetop.
Looking like an Emerald in the sun, this female Ruby-throated Humming bird pauses during her feeding run.
Male Ruby-throated Hummingbird with head turned slightly.