Commentaire : The bright ruby-red cap golden-topaz throat/upper chest of this bird is not due to constitutional pigment but is a consequence of the physical structure of the feathers in these areas. These feathers act as refractors diffraction gratings -the refractive elements split white light into its constituent colours (like rain in sunlight creating a rainbow) -most of the colours are then filtered out by the diffractive elements leaving a pure bright irridescent colour. But all this depends on sunlight hitting at just the right angle!
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Mis à jour le 19/11/2008 05:05:56 - © 1996-2008 Oiseaux.net