Its true that flamingos get their color from the food they eat, which is small brine shrimp, plant plankton and blue-green algae (1). The substances are carotenoid proteins found in the food. They are broken down into pigments by the liver and show in the plummage ( which is basically a whitish grey without the pigments from the food ). The colour of the flamingo is determined in large part by the type of food it eats :)

In the wild very pale flamingos are considered 'unhealthy' because they are not getting enough carotenoids in their diet. In zoos flamingos are often given a food additive called Roxanthin Red which keeps their plummage pink even if the diet is lacking in the necessary proteins. Not all zoos colour their flamingos ( one of our zoos has a sign saying why the flamingos are white but I can't remember which one it is )

A variety of colours.....and species. There are lots of different species ( the list is at source 1 )

http://www.allaboutwildlife.com/wp-content/uploads/2009/11/FlamingoAaronLogan.jpg

http://generik.smugmug.com/photos/4771934-M.jpg

http://www.bestroyaltyfreeimages.net/best-royalty-free-images-love-pink-flamingos-Kjunstorm-picture.jpg

Wild flamingos eat algae, small insects, and small crustaceans like shrimp. These foods are rich in beta-carotene. Beta-carotene is the pigment that gives carrots their orange coloring. It also tints flamingos' feathers pink.

What Do Flamingos Eat - http://www.wildlife-animals.com/flamingo/what-do-flamingos-eat.php