[CT Birds] Hummingbird Awareness, Part 2

David F Provencher david.f.provencher at dom.com
Tue Jul 12 13:03:22 EDT 2011


Frank, as you probably know, iridescent colors in the gorgets of Hummingbirds are created structurally by minute feather structures that refract incident light, as opposed to being cause by pigments. Perhaps with these individuals, the structures are slightly different than the normal population, and the refraction of the incident light is slightly different. Not being very knowledgeable about structural colors and refracted light, I wonder if it also might be possibly caused by the incident light being already somewhat altered through atmospheric refraction. An empirical answer to that would be to see the ruby color on one bird and the orange/yellow on another at the same moment. My gut tells me however that the variant structure seems far more likely, but I would love someone with a deeper understanding of structural color anomalies to chime in here.

Dave


-----Original Message-----
From: ctbirds-bounces at lists.ctbirding.org [mailto:ctbirds-bounces at lists.ctbirding.org] On Behalf Of Frank Mantlik
Sent: Tuesday, July 12, 2011 5:28 AM
To: Mark Szantyr; ctbirds at lists.ctbirding.org; Louis Bevier; Steven Mlodinow; Greg Hanisek; Nick Bonomo; Bob Sargent
Subject: Re: [CT Birds] Hummingbird Awareness, Part 2

Mark,
That's interesting.  I'd forgotten about it, but I too have seen, once or twice, 
 male Ruby-throateds with that orange-yellow iridescence.  I assumed it was just 
an odd variation.

Frank Mantlik




________________________________
From: Mark Szantyr <birddog55 at charter.net>
To: ctbirds at lists.ctbirding.org; Louis Bevier <lrbevier at colby.edu>; Steven 
Mlodinow <SGMlod at AOL.COM>; Greg Hanisek <ghanisek at rep-am.com>; Nick Bonomo 
<nbonomo at gmail.com>; Bob Sargent <RubyThroat at aol.com>
Sent: Mon, July 11, 2011 11:38:17 PM
Subject: [CT Birds] Hummingbird Awareness, Part 2

Well, I learned something today.  Last week I observed an apparent male
Ruby-throated Hummingbird at a local feeder but rather than showing the rich
ruby red iridescence in the gorget, this bird was orange to orange-yellow,
similar in color to the orange of an adult male Baltimore Oriole.  In every
other way it appeared to be a typical Ruby-throated male.   I contacted Bob
Sargent, the guru of hummingbird banders and Ruby-throat aficionado,
described the bird and he mentioned that he has seen birds in molt show this
type of coloring.  Today, I was able to get some images of the bird.  I used
a very high ISO as I wanted to use natural light and not flash in order to
keep the colors close to what I was seeing in the field.  Though the images
are far from stellar, lo and behold, this bird WAS in molt.  Perhaps some
aspect of this process somehow altered the reflective properties of the
gorget and the typical rich red was now reflected as orange.  Again, a
lesson in not putting all of your eggs in the "one field-mark" basket. The
gallery is below andI include an image of a more typical ruby-throated
Ruby=throat for comparison.

http://birddog55.zenfolio.com/p145646176

Mark

Mark S. Szantyr
80 Bicknell Road #9
Ashford, Connecticut 06278
USA

1-860-487-9766
Birddog55 at charter.net



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