Chilean Flamingos (P. chilensis) gregarious wading birds in the genus Phoenicopterus and family Phoenicopteridae. They are found in both the Western Hemisphere and in the Eastern Hemisphere, but are more numerous in the latter. There are four species in the Americas and two species in the Old World. Two species, the Andean and the James's Flamingo, are often placed in the genus Phoenicoparrus instead of Phoenicopterus. Flamingos filter-feed on brine shrimp. 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 flamingo's characteristic pink colouring is caused by the Beta carotene in their diet. The source of this varies by species, but shrimp and blue-green algae are common sources; zoo-fed flamingos may be given food with the additive canthaxanthin, which is often also given to farmed salmon. Flamingos produce a "milk" like pigeon milk due to the action of a hormone called prolactin (see Columbidae). It contains more fat and less protein than the latter does, and it is produced in glands lining the whole of the upper digestive tract, not just the crop. Both parents nurse their chick, and young flamingos feed on this milk, which also contains red and white blood cells, for about two months until their bills are developed enough to filter feed. Flamingos frequently stand on one leg. The reason for this behavior is not fully known. One common theory is that tucking one leg beneath the body may conserve body heat,[4] but this has not been proven. It is often suggested that this is done in part to keep the legs from getting wet, in addition to conserving energy. As well as standing in the water, flamingos may stamp their webbed feet in the mud to stir up food from the bottom. Young flamingos hatch with grey plumage, but adults range from light pink to