In many birds, red, orange and yellow feathers are coloured by carotenoid pigments, but parrots are an exception. For over a century, biochemists have
known that parrots use an unusual set of pigments to produce their rainbow of plumage colours, but their biochemical identity has remained elusive
until recently. Here, we use high-performance liquid chromatography to survey the pigments present in the red feathers of 44 species of parrots
representing each of the three psittaciform families. We found that all species used the same suite of five polyenal lipochromes (or psittacofulvins)
to colour their plumage red, indicating that this unique system of pigmentation is remarkably conserved evolutionarily in parrots. Species with redder
feathers had higher concentrations of psittacofulvins in their plumage.
Scientists believe that the brilliant parrot colors arise from either supramolecular or covalent interactions of the psittacofulvins with structural
proteins in feathers, with shorter chain psittacofulvins producing yellow colors and longer chains producing red. Green feathers arise from a
combination of a psittacofulvin and melanin, and blue and black feathers come from melanin alone.
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