Shimmering iridescent colors such as those found in hummingbirds and peacocks are caused by special structures, air bubbles, or films on feather surfaces. These modifications interfere with the bending and scattering of light to strengthen some wavelengths and cancel out others. A flamingo's pink coloring comes from the bird's diet of small crustaceans and algae, which are full of carotenoid pigments. Captive flamingos may lose their bright colors without special dietary supplements. Unlike many animals, birds can distinguish colors.
Birds use colors and patterns to communicate with each other.
These may send messages of aggression, attraction, or alarm. Birds can recognize members of their own species by their color patterns, just like uniforms identify sports teams. Many species attract mates or defend territories with the help of flamboyant advertising plumage.