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Why are flamingos pink?

Male blackbirds are a dark colored species, but have a distinctive beak color all year long.
Thomas de Padova

Male blackbirds have a dark plumage. The species is characterized by its distinctive beak color. The coloring substances, carotenoids, are an essential component of their food. If they are well fed and healthy, its beak shines deeply orange. By this, the males attract the females and stand out from its yellow-beaked rivals. 

Carotenoids are available in hundreds of different varieties; the color range goes from yellow to pink flamingo to purple. Only plants produce carotenoids, as they are important for photosynthesis. For instance, apricots and oranges obviously are rich in beta-carotene, and even more of it can be found in carrots or pumpkins – but also in broccoli the color pigments are covered by the dominating green chlorophyll.

Beta-carotene is very healthy. It absorbs free oxygen radicals and makes cancer-causing substances harmless. “Skin with a high amount of beta-carotene is better protected from sunlight,” says Bernhard Watzl, nutritionist at the Max Rubner Institute in Karlsruhe. The skin does not turn red so easily. “When toddlers regularly eat carrot mash and drink carrot juice, they get noticeably colored cheeks,” says Watzl. The skin of adults can also contain beta-carotene, coloring their palms and face.  

Nevertheless, anyone feeding flamingos with carrots – it was actually trialed in zoos – waits in vain for a pink plumage. The Caribbean pink flamingo and its related species shine in vibrant colors since they consume a specific type of highly concentrated carotenoid, for example through crabs, which in turn live on algae. Algae of the Dunaliella genus are extremely colorful. If this food is not available, the birds will lose their bright colorful plumage with the next molt and thus, are no longer well protected against infectious diseases.

Flamingo’s beautiful coloring, however, only commences at a more mature age. Initially young birds have a grey down. The flamingo parents feed their littles with milk rich in carotenoids. It takes years before the grey plumage turns pink or orange. Like blackbirds, the flamingo’s appearance is crucial for survival: Without the proper feather color, they will not attract potential partners and hence have no offspring. Thomas de Padova

Translation of article: Warum sind Flamingos rosa? (https://www.tagesspiegel.de/wissen/aha-warum-sind-flamingos-rosa/1315170.html), Der Tagesspiegel, 03.09.2008