| Shimmering in the Sun A male rubythroat's gorget may not always look bright red. Sunlight is the key to seeing the color. The brilliant, iridescent colors are caused by the refraction of light by the structures of certain feathers. Like a prism, feather structures split light into its component colors. Only certain frequencies are refracted back to viewers' eyes. The apparent color of any part of a feather depends upon the distance between the microscopic ridges in its gridlike structure. The resulting colors are more vivid and iridescent than those of birds with only pigmented feathers. Not all hummer colors are due to feather structure; the duller, rusty browns of Allen's and Rufous Hummingbirds are the result of pigmentation. Iridescent hummingbird colors actually result from a combination of refraction and pigmentation, since the diffraction structures themselves are made of a pigment called melanin. |
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