[Birdtalk] Re: Red Butte Warbler ID

[Rick Fridell]

Hello Everyone,

This is indeed an intriguing warbler.

I think it clearly is not a Blackpoll or Bay-breasted Warbler, primarily for
all the reasons Craig outlined. In addition, among other important missing
characteristics a fall Blackpoll or Bay-breasted should show more distinctly
white-tipped primaries.

I agree it superficially resembles a first fall Chestnut-sided Warbler, but
there are a couple major problems with this. First and foremost, the warbler
shows significant (blurry) streaking on the chest, sides, and flanks
(particularly evident in photo 4). This streaking is inconsistent with any
Chestnut-sided Warbler plumage.  Also, a fall Chestnut-sided Warbler should
show a marked contrast between the face and crown and a slight contrast
between the face and white throat. This bird appears to show a strong
contrast between the throat and the face but no evident contrast between the
auriculars and crown. I agree the wingbars appear yellowish in a couple of
the photos (good for Chestnut-sided), but I'm not convinced this isn't an
artifact of the lighting in the photos.

I'm a little surprised no one has brought up a first-fall Pine Warbler.
Many characters visible in the photos (particularly photos 4,5, and 6) fit
well for a young Pine Warbler (auricular pattern / throat contrast, breast
smudging / streaking, bill color, tail pattern and length, etc.). However I
think Photo 1 shows indistinct streaking on the back (although it's hard to
tell for sure) and as hard as I try to split the eye-ring, it just looks too
complete at the rear of eye, and unfortunately these characters should
eliminate a Pine Warbler.

So after trying to make it fit a vagrant eastern warbler, I'm actually back
to a more obvious and probable candidate (as Matt and Cliff hinted
towards),...... I believe it is actually a first fall Yellow-rumped Warbler.

I really don't see any features on this bird that would be terribly
inconsistent with a first fall Yellow-rumped Warbler. As Matt pointed out,
the complete or nearly complete eye-ring is fairly common on "some drab fall
female yellow-rumps".  In every photo the eye-ring appears to be slightly
incomplete towards the front of the eye (appropriate for a yellow-rump). The
auricular and throat contrast is appropriate for first-fall yellow-rumps as
well, which often show whitish throats and chins.  Other characteristics are
also consistent with a young Yellow-rump Warbler, including the indistinct
streaking on the breast, sides and flanks; the back pattern (thin indistinct
streaking, in photos 1 and 2); the prominent wingbars, tertial and primary
edging; the overall proportions, etc. Tail length (projection past undertail
coverts) looks a bit short for a yellow-rump, but this is hard to judge in
the photos, and the appearance can be easily influenced by the angle of the
photo. I would also expect a yellow-rump's bill to be darker overall, but
young birds can show a paler area at the base of the lower mandible. Also I
think the tail pattern shown in one of Carol's newly posted photos (#4) is a
better fit for a Yellow-rumped Warbler and shows too much black in the tips
of the outer retrices for a chestnut-sided. Of course all plumages of
Yellow-rumped Warblers should show an obvious yellow rump, and I actually
think a bit of the yellow rump may be visible in Photo 3 (lighter areas),
although it's hard to judge with the shadows in the photos. If that's not a
yellow rump than disregard all of the above, and I don't know what it is.

A special thanks to Carol for sharing the photos and providing the extra
images. It's always fun to puzzle over a good old fashioned "confusing fall
warbler".

Regards,

Rick Fridell
Hurricane, UT


-----Original Message-----
From: birdtalk-bounces at utahbirds.org
[mailto:birdtalk-bounces at utahbirds.org]On Behalf Of Matt Mills
Sent: Friday, October 03, 2008 3:47 PM
To: birdtalk at utahbirds.org
Subject: [Birdtalk] Re: Red Butte Warbler ID


Hey all,

To me the most interesting feature on this bird is the head. It seems to be
clean and greyish with the eye-ring the only prominent feature. Also, the
clean demarcation of the contrasting lighter throat and how all of the
streaking on the breast begins along a straight line. To me these features,
along with the undertail pattern make this bird look a bit like  a
Yellow-rumped Warbler.

I realize other things are missing (and that it's almost certainly NOT a
YRWA, but I'm just chiming in here) - there doesn't appear to be any yellow
on the rump in Photo #3 , the back appears quite green in Photo #2, there is
no eye line in any of the photos and the eyering appears to be complete -
But some drab fall female yellow-rumps show a fairly plain grayish head and
rather complete white eyering.


Anyways, the shape and expression seem to best fit Chestnut-sided Warbler,
as does the colour and pattern of the back, and the fact that the edges of
the secondaries appear yellowish (much more so than the wingbars). It's just
the streaking on the breast that calls it into question.

I still think that Blackpoll and Bay-breasted are possibilities given the
variability that exists in their fall plumages, and the similiarities
between the species.

Hopefully this weekend turns up more warblers.

Cheers

Matt Mills




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