In nature, the flamingo gets the red feather color from the microscopic crustaceans and algae it eats. In zoos one cannot feed the flamingos with the small crustaceans and algae and therefore have to offer the flamingo dye in a different way. In the beginning, the flamingos in the zoos got plenty of paprika, but it didn't stain enough. Today, they have switched to giving the flamingos canthaxanthin - a dye that is closely related to the dye beta-carotene, which is found in carrots, for example. Flamingos in captivity that are not offered dye such as canthaxanthin, will lose the red color after the shift.