Pink Blanket Of Flamingos, Rift Valley Lakes, Nakuru Lake National Park, Kenya

Young flamingos hatch with grey plumage, but adults range from light pink to bright red due to aqueous bacteria and beta carotene obtained from their food supply. A well-fed, healthy flamingo is more vibrantly coloured and thus a more desirable mate; a white or pale flamingo, however, is usually unhealthy or malnourished. Captive flamingos are a notable exception; many turn a pale pink as they are not fed carotene at levels comparable to the wild. This is changing as more zoos begin to add prawns and other supplements to the diets of their flamingos.
Feeding
Flamingos filter-feed on brine shrimp and blue-green algae. Their oddly shaped beaks are specially adapted to separate mud and silt from the food they eat, and are uniquely used upside-down. The filtering of food items is assisted by hairy structures called lamellae which line the mandibles, and the large rough-surfaced tongue. The pink or reddish color of flamingos comes from carotenoid proteins in their diet of animal and plant plankton. These proteins are broken down into pigments by liver enzymes. The source of this varies by species, and affects the saturation of color. Flamingos whose sole diet is blue-green algae are darker in color compared to those who get it second hand (e.g. from animals that have digested blue-green aglae). Zoo-fed flamingos, who often lack the color enhancer in their diet, may be given food with the additive canthaxanthin.