[obol] Re: Union County, OR :' a very black-backed male' LESSER GOLDFINCH

  • From: Mark Nikas <elepaio@xxxxxxxxx>
  • Date: Thu, 26 Jun 2014 17:03:15 -0700

Trent,

This topic came up on OBOL several years ago and a number of birders
reported encounters over the years with black or very dark backed Lesser
Goldfinches from various areas around the state. Dan Gleason wrote a good
post on the topic that I squirreled away. It's pasted below.

Concerning Lesser Goldfinches with black backs:



I think that we need to keep in mind that this a a species which has not
been well studied in comparison to many other species. Dark-backed males
apparently do occasionally appear in males of the race of Lesser Goldfinch
found in western Oregon. In most instances, these individuals will still
show a green tinge around the nape and not be so solidly glossy black as
the birds found in Mexico and southern Texas. Both forms occur with greater
frequency in the race found in the eastern portion of this species range
(Colorado to Texas). More black-backed forms occurr as one proceeds from
north to south. This has led some authors to assume that this is a
polymorphic species with both color phases occurring in the population, but
not everyone goes along with this idea. I don't believe that the genetics
of this species has been closely examined so it is hard to know if we are
seeing individuals that differ based strictly on genetics or if the
variability is caused by other factors.





In any event, I would suspect that the birds being seen and reported here,
fall with the range of known variability for our race of Lesser Goldfinch
(Carduelis pasltria herperophilus). It seems unlikely that southern birds
have wandered into Oregon, especially at this time of year. Consider also,
that this species is not considered migratory. Some individuals do wander,
more so in northern birds than southern populations, and there is some
altitudinal movements known that are associated with the seasons. But no
long distance movements have been traced. This remains a species about
which we still have much to learn.



Dan Gleason     7/26/07




On Thu, Jun 26, 2014 at 3:00 PM, Redacted sender AVITOURS@xxxxxxx for DMARC
<dmarc-noreply@xxxxxxxxxxxxx> wrote:

> Birders -
> Yesterday (6/25, 4:30 PM), I  received a call from La Grande birder,
> Michael Wiens.  He had phoned to ask  if the black backed subspecies of
> LESSER
> GOLDFINCH has occurred in Oregon  before, and that he had a very
> dark-backed
> LESSER GOLDFINCH coming to his  Thistle Feeder .  I did not know.
>  Marshall,
> D.B., M.G. Hunter,  and A.L. Contreras, Eds. 2003. Birds of Oregon: A
> General
> Reference. Oregon  State University Press, Corvallis, OR. pg 608, states
> that "Birds reported as  'black-backed' in se. Oregon could be C.p.
> psaltria
> (Texas) or a variation in  hesperophila (PNW & SW), specimens would be
> necessary for  confirmation.  Sibley mentions that the back color of Lesser
> Goldfinch  varies geographically, with virtually all adult males in
> southern Texas
> having  black backs and virtually all adult males west of Colorado and New
> Mexico are  gree-backed.  Beadle & Rising's Tanagers, Cardinals & Finches
> of
>  the US & Canada talk about the substantial differences between the molts
> of  the two subspecies and thumbing through Pyle's Identification Guide to
> North  American Birds is a bit difficult for me to follow being that I am
> not
> a bander  and I am currently trying to gain a better understanding of molt.
>
> I ran over to Michael's house and together we took a few photos.  The  best
> photos can be viewed  here:
> http://ebird.org/ebird/view/checklist?subID=S18918274
> In one of my  other photos, white shows clearly in the tail, which may
> eliminate the  black-backed subspecies.  This is definitely the darkest
> back/auricular  colored LESSER GOLDFINCH I have ever seen in Oregon.
>  Anyone have
> any  experience with dark-backed LESSER GOLDFINCHES outside of Texas?
> Good  birding,
> - Trent Bray
> The Bobolink - Linking Birders & Birds
> 1707  5th Street
> La Grande, OR  97850
> (541) 963 - 2888
> avitours@xxxxxxx
>
>
>
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