Flamingos at Riverbanks Zoo. Flamingos are one of the oldest bird groups. Their fossils date back 30 million years. They get their color from the amount of carotenoids they eat. Carotenoids are a nutrient that also makes carrots orange and tomatoes red. Flamingos favorite foods include shrimp, snails and algae. The bird plunges it's head into the water, twists it upside down and scoops the catch using its upper beak like a shovel. Flamingos lay one egg at a time. The female lays the egg on a mound of mud and then both parents take turns sitting on it to keep it warm until it hatches in about 30 days. Flamingos live 20 to 30 years. The flamingos at Riverbanks Zoo are vibrant-colored and fun to watch.