Lack of the proper pigment in the diet is a frequent cause of orange to yellow
in House Finches, but very often, illness also plays a significant role. If the
diet is good and the bird is not ill at its next molt, coloration will likelhy
be normal. Unfortunately, with Mycoplasma conjunctifitis, the birds seldom, if
ever, recover.
Carotenoid pigments are also taken up by the immune system, especially when the
birds are ill. So if this bird had the disease at the time the feathers were
developing, there may not have been enough pigment available, even if the diet
is food, to incorporate into the feathers after the immune system took what it
needed.
Mycoplasma, (several species) are a common, worldwide poultry disease. This
disease was unknown in western House Finches. The House Finch is not native to
the east, but was introduced on Long Island in 1939 and spread quickly. In
1994, this disease was discovered in House Finches in the Washington DC area
and rapidly spread throughout the eastern population. It wasn't until 2006 that
any western birds were were seen with this disease. This was soon after the
eastern population had spread westward to encounter western finches in the
region of the Rockies, bringing with it this disease.
Dan Gleason
Dan Gleason
Owner, Wild Birds Unlimited of Eugene
Ornithology Instructor, University of Oregon
dan-gleason@xxxxxxxxxxx
On Mar 20, 2017, at 7:39 PM, Range Bayer <range.bayer@xxxxxxxxx> wrote:
Hi,
A yellowish male House Finch came to Chuck Philo's Toledo feeder on
March 18. It had "House Finch Eye Disease" (Mycoplasmal
conjunctivitis) in both eyes
(http://feederwatch.org/learn/house-finch-eye-disease/ that includes
photos of it and of House Finches with avian pox). But it had not
progressed to where the eyes were swollen shut. It seemed sick and
acted sluggish and allowed closer approach than normal. It did not
show up on March 19.
Yellow House Finches develop when certain carotenoid pigments are
deficient in the diet during molt (see "Yellow House Finches" at
http://feederwatch.org/learn/unusual-birds/#color-variants).
Could a dietary deficiency made this House Finch more susceptible to
this eye disease?
Range Bayer, Newport, Oregon.
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