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J Exp Biol. 2013 Dec 1;216(Pt 23):4358-64. doi: 10.1242/jeb.091561. Epub 2013 Sep 12.

Spectral tuning of Amazon parrot feather coloration by psittacofulvin pigments and spongy structures.

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Computational Physics, Zernike Institute for Advanced Materials, University of Groningen, NL-9747 AG Groningen, The Netherlands.


The feathers of Amazon parrots are brightly coloured. They contain a unique class of pigments, the psittacofulvins, deposited in both barbs and barbules, causing yellow or red coloured feathers. In specific feather areas, spongy nanostructured barb cells exist, reflecting either in the blue or blue-green wavelength range. The blue-green spongy structures are partly enveloped by a blue-absorbing, yellow-colouring pigment acting as a spectral filter, thus yielding a green coloured barb. Applying reflection and transmission spectroscopy, we characterized the Amazons' pigments and spongy structures, and investigated how they contribute to the feather coloration. The reflectance spectra of Amazon feathers are presumably tuned to the sensitivity spectra of the visual photoreceptors.


barbs; barbules; melanin; thin films; vision

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