Flamingos Are Born Gray and Make Their Own Pink Dye

Flamingo chicks hatch covered in white or pale gray down. The pink that defines the adult bird — and every flamingo in every zoo poster — is not genetic. It comes entirely from carotenoid pigments absorbed through food: primarily cyanobacteria, diatoms, and brine shrimp (Artemia) that inhabit the alkaline and saline lakes where flamingos feed.

Carotenoids are the same class of pigments that make carrots orange and tomatoes red. Flamingos can't synthesize them and can't store reserves for long. A flamingo given a carotenoid-free diet fades within months, and captive flocks need carefully managed diets — or carotenoid supplements added to their feed — to maintain color. Some zoos have used paprika or dried shrimp; others add synthesized canthaxanthin.

During breeding season, the biology gets stranger. Parent flamingos of both sexes secrete a crop milk to feed their chicks, and this milk is pink — tinted by carotenoids the parent diverts from its own feathers into the secretion. Breeding adults visibly pale during nesting as the pigment migrates from plumage to milk. Researchers at the Wildfowl & Wetlands Trust documented the color shift in 2015, showing that the most attentive parents were also the most faded.

The pigment reaches the feathers via oil from the uropygial gland. Flamingos preen extensively, and the carotenoid-tinged oil coats each feather shaft, deepening the color over time.