We a birding trip to Cuba in 2013. Among the many birds we saw was the American Flamingo. They were close to the road, so we were able to get excellent looks at them and all of their color variations.
Flamingos are born a dull gray. Their bright color develops over time depending on what they eat. Their diet consists of algae and brine shrimp, both are rich in beta-carotene (carotenoids). The naturally red, yellow or orange pigments from their food are absorbed and deposited in their feathers, giving them their vibrant appearance.