[EBB Sightings] Yellow Variant House Finch? + Robins

	
	

Hi all,

The first thing that comes to mind with ripe berries is a very common
intoxicant: ethanol.  I'd guess the robins are drunk.  Or at least buzzed.

As far as I know, research on House Finch coloration has been all in the
lab.  Geoff Hill of Auburn University is the main guy on this.  He had
captive house finches that were fed diets that varied in the amount of
added carotenoid pigment.  When fed a diet rich in a red pigment (I forget
the names), the birds all acquired red feathers during their next molt. 
With a carotenoid-poor diet, they became yellow in the next molt, and with
another pigment they became orange.  I believe they were fed apple pieces
that had the added pigment.  It should be (and has been) noted that these
conditions do not necessarily correlate to the wild.  When pumped full of
pigments, they turned red, and this may have over-ridden any genetic
variability between the birds.  So the research is considered sound, but
might not be entirely applicable to wild birds.

It is certainly possible that in the wild, the amount of available
pigments (or precursors) in the diet are insufficient to overwhelm
variation the birds' genetic ability to process and store the pigments. 
At the same time, the color the birds would be due to conditions prior to
the last molt, so Mr Yellow might have had a different diet then and may
have been located somewhere else entirely then his red friends.

Jaan Lepson
Livermore, ALA

On Mon, June 15, 2009 10:49 am, Robert Dailey wrote:

> all,
> yesterday my wife and i did castle rock and saw one of the yellow hf
> variant males in a flock of bright red ones.  the diet as sole
> explanation seems too simple.  all these finches are presumably eating
> the same diet, so why one yellow in their midst???  my guess is that
> there is something else going on, for instance a genetic variation in the
> yellow variant which processes the dietary colorants differently.  i know
> nothing of the scientific evidence that diet determines color in the hfs
> [i presume it's sound], so maybe i'm all wet, but all ideas would be
> welcome.
> while on the subject of "explanations".......why the crazy behavior of
> robins eating ripe pyrocantha berries?  i forget the explanations that
> i've heard proposed, but i have my own theory [again, wet?].  the
> behavior of the robins is totally out of character.  they are
> hyperactive, fly about erratically and "flightily" [pardon], squawking
> continuously.  in short, they act as tho they're on crack cocaine or
> meth.  could there be some sort of stimulant in the berries?  has anyone
> ever checked the berries for same?  IDEAS?  Erudition?  thanks.
> bob dailey
> Date: Fri, 12 Jun 2009 09:45:23 -0700
> Subject: Re: [EBB Sightings] Yellow Variant House Finch?
> From: calw at mac.com
> To: de.lombardi at gmail.com; rhislop at astound.net
> CC: sightings at diabloaudubon.com
> We?ve had one (assuming it is the same each year) at our feeder in
> Piedmont.  In the same flock we see from Yellow to orange to dark red.
> Calvin Walters
> 1-510-717-5500
> calw at cowalters.com
> From: Dave Lombardi 
> Date: Wed, 10 Jun 2009 12:18:04 -0700
> To: Bob Hislop 
> Cc: East Bay Birds 
> Subject: Re: [EBB Sightings] Yellow Variant House Finch?
> Yes, we had one yellow variant house finch visit our backyard in
> Rockridge this week (100% positive).
> Dave Lombardi
> Oakland.
> On Wed, Jun 10, 2009 at 11:13 AM, Bob Hislop  wrote:
> Just observing our daily mix of backyard birds and I noticed what looked
> like a yellow male House Finch foraging among its red cousins.  I'm not
> 100% positive on this so I was wondering if anyone else has recorded this
> variant in the east bay?  (I didn't get a very long observation time as
> the neighborhood feral cat came wandering through on its daily rounds.)
> Bob Hislop
> Walnut Creek
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-- 
Jaan Lepson

University of California
Space Sciences Laboratory
7 Gauss Way
Berkeley, CA 94720-7451