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For more than a century, biochemists have known that parrots use an unusual set of pigments to produce their rainbow of plumage colors, but their biochemical identity has remained elusive. Now, an Arizona State University researcher has uncovered the chemistry behind the colors of parrots, describing on a molecular level what is responsible for their bright red feathers.

The work casts a new light on what is chemically responsible for the colors of birds, and defies previous assumptions and explanations for color variations in parrots, said Kevin McGraw, an assistant professor in ASU's School of Life Sciences.

"Evolutionary biologists have not really thought hard about parrot coloration," said McGraw. "This research is exposing a whole new world of color communication in parrots and the potential physiological and biochemical roles of the new molecules we found in our work."

Details of the work are in a paper, "Distribution of unique red feather pigments in parrots," by McGraw and Mary Nogare, a parrot fancier from Snoqualmie, Wash., published in the Feb. 16, 2005 issue of the journal Biology Letters.

Animals, like birds and fishes, commonly use biochromes like carotenoids to acquire red, orange or yellow coloration, but McGraw and Nogare found that these compounds are not responsible for the red colors found in the parrot species they sampled.

The researchers used a chemical analysis technique called high-performance liquid chromatography to survey the pigments present in red parrot feathers. McGraw and Nogare collected and analyzed samples from 44 parrot species that have red feathers. Overall, there are some 350 species of parrots, 80 percent of which have red in their plumage.

They found a suite of five molecules, called polyenal lipochromes (or psi
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Source: Netherlands Organization For Scientific Research