Subject: Re: house finch plumages - was orioles/genetics
Date: May 3 19:54:19 1995
From: Burton Guttman - guttmanb at elwha.evergreen.edu



Teresa Michelsen replied to Jon Anderson with,
>
> That's interesting!! I hadn't imagined that plumage color could be affected
> by dietary deficiencies during individual molts. Of course, I also don't
> know of that many cases where there are different plumage colors in the same
> bird species that are genetically determined, like hair color in humans. i
> probably didn't make it clear enough that I was just proposing an example of
> how genetics could result in that kind of outcome. There may be a lot of
> alternative explanations for individual cases that are plausible. I have a
> small flock of house finches in my yard - two of the males are red and one
> is orange. I wonder why one of them isn't getting the same diet as the
> other two? competition for food?? - Teresa

Jon had written,

> Teresa,
>
> My reading and understanding of male house finch plumage is that the
> yellow, gold, orange plumages are a result of a deficiency of beta-
> carotene in the individual bird's diet when the colored plumage is
> developing during each molt, and are *not* dependent upon genetics.


There was a whole long thread about this on Birdchat, and I can send the
whole thing to anyone who's interested. The most informative message was
the following:


Date: Mon, 1 May 1995 22:43:42 -0700 (PDT)
From: Joe Morlan <jmorlan at slip.net>
To: Burton Guttman <guttmanb at ELWHA.EVERGREEN.EDU>
Cc: Multiple recipients of list BIRDCHAT <BIRDCHAT at LISTSERV.ARIZONA.EDU>
Subject: Re: Info on yellow/orange variant of House Finch

I found the following on pg. 88 in "Ornithology" by Frank Gill (2nd
edition):

"Male House Finches vary in plumage color from bright to pale red
or even yellow-orange. With a series of elegant experiments, Geoffrey
Hill (1990, 1991, 1992, 1993) has demonstrated not only that plumage
color of male House Finches reflects their diet but also that females
prefer brightly colored males over dull-colored males.

"High-quality males apparently have intrinsically superior
foraging ability and better access to carotenoid-rich foods that brighten
their colored badges. Both the intensity and extent of red carotenoid
pigmentation in the plumage reflect the carotenoid pigments they eat
while they are replacing their feathers during the annual molt; these
finches cannot use carotenoids stored in advance of the molt to achieve a
brighter plumage.

"Because bright red pigmentation serves as an accurate badge of
male quality, female House Finches use the red color badge to pair
preferentially with the best males. Brightly colored males are better
providers for their families -- they bring more food to their females
during incubation and to their nestlings. Females paired with dull
colored males more often abandon the breeding effort, apparently because
of inadequate provisioning by their mates. Bright red males also survive
the winter better than dull males and thus are available for more than
one breeding season."

----------
Joe Morlan
Albany, CA
jmorlan at slip.net