The white color of this albino peacock is due to the missing black melanine pigment. The usual rich colors of the peacock are seen because black pigment which absorbs most of the incident light, allowing us to see only the interference colors. In this peacock, the interference is still happening, but the effect is entirely washed out by the abundance of white light. In this albino, you can see that the “eyes” of the tail feathers are clear, not colored.
Via the Evilutionary Biologist, a fun website about the science of color – not just the biology of our eyes, but the physical properties of objects that make them appear colored. Why is water in the sea blue, but water in a glass clear? How is the glow of lightning different than that of a light bulb? What causes the rainbow of color “in” an opal? There’s quite a bit here I didn’t know, or don’t understand as well as I should!
The website is maintained by an organization called IDEA. Some of the pages are under construction, and unfortunately the dates suggest the project may be abandoned, but at least it’s a good start for future reading. IDEA also has a mixed bag of other websites, including color vision and art, pigments, scientific analysis of old masters, and butter. (One of these things is not like the others. . . !)