Bird feather colors come from two main sources: pigments and structural colors. Pigments like melanin create blacks, browns, and reds, while carotenoids produce yellows, oranges, and some reds. Structural colors are created when light interacts with the microscopic structure of feathers, producing blues, greens, and iridescent effects.
The most common pigment is melanin, which also strengthens feathers. Carotenoids must be obtained through diet, which is why flamingos turn pink from eating shrimp. Some of the most spectacular bird colors, like the blue of a Blue Jay or the iridescent throat of a hummingbird, come from structural coloration rather than pigments.