[EBB Sightings] Steller's Jay Oddity - color blue

With the exception of a few birds in the old world, no birds have blue
pigmentation in their feathers.  A pigment is a chemical that absorbs light
of colors that it is not (red pigment absorbs green & blue light, so it
looks red).  If you put clear oil on water, you see all the colors of the
rainbow being reflected.  So the colors you see are not from any pigment,
but from light interference pattern on the thin oil film.  There are
microscopic structures in the feather that produce the blue reflected light.
So for the blue head of the Jay, the microscopic structures were missing, or
the angle of the light was such that you did not see the blue.  The dark
blue color comes from brown pigment and the blue refecting microscopic
structures.  I have seen bluebirds appear brown because of the lighting.
After it moved into sunlight, it appeared blue.

Ralf Stinson

-----Original Message-----
From: sightings-bounces at diabloaudubon.com
[mailto:sightings-bounces at diabloaudubon.com] On Behalf Of Donald Lewis
Sent: Sunday, July 05, 2009 22:40
To: MDAS Sightings
Subject: [EBB Sightings] Steller's Jay Oddity

Sunday morning,  a Steller's Jay with a totally brown head was feeding a
fledgling on our deck. I've never seen a Jay like that. I guess a form of
less-than-normal pigmentation but I'm curious if others have seen a similar
bird.

Don Lewis
Lafayette, CA
donlewis at comcast.net