[obol] Re: id help needed!
- From: David Irons <llsdirons@xxxxxxx>
- To: linda Fink <linda@xxxxxxxx>, OBOL Oregon Birders Online <obol@xxxxxxxxxxxxx>
- Date: Thu, 23 Oct 2014 06:17:26 +0000
Linda,
There are several clues here that I think help answer your warbler ID question.
Here's what I see.
1. Vegetation -- The deciduous tree in the photo is just starting to bud and
leaf out. In the Willamette Valley that typically happens from late March to
mid-April with bigger trees. You say this photo was taken in April, but don't
give us the exact date. I think that if this image had been taken in the latter
days of April the leaf out would be further along. This alone likely takes
Yellow Warbler out of the equation. The first northbound Yellow Warblers
normally arrive in the Willamette Valley about 25 April or later and they are
generally scarce before the 1st of May.
2. Undertail coverts -- Another strike against Yellow Warbler is the length of
the undertail coverts (along with the lack of yellow going out to the end of
the tail, which you mention). Yellow Warblers have long undertail coverts,
which tend to make the tail look short from below, which is clearly not the
case with this bird.
3. Bill shape -- Looking at the bill of this bird, the tip seems somewhat
blunt. Orange-crowned Warblers and other species in the genus Oreothlypis
(formerlyVermivora) have thin bills that come to a very sharp point. On bill
shape alone I think we can eliminate Orange-crowned Warbler, which leaves us
with only Wilson's Warbler as a likely candidate (the only other all-yellow
warbler that one would expect in Oregon during April).
4. Bill color -- This is the clincher. The underside of the bill is very pale
and looks quite yellowish. After hatch-year Orange-crowned Warblers have
all-dark bills with no yellow whatsoever. Conversely, Wilson's Warblers show
yellow mandibles (the lower half of the bill). In spring, Yellow Warblers also
have dark bills.
5. Tertial edges -- On the top photo I think that we can see enough of the
upper wing to determine that edges of the tertials (the inner most folded
feathers on the wings) do not contrast with the rest of those feathers. In all
plumages, Yellow Warblers have darker duskier tertials with noticeably pale
edges. This is a great field mark if you are ever struggling to sort out dull
immature Yellows and Orange-crowneds.
Given the presumed date (based on condition of the vegetation), the mostly
yellow coloration, the somewhat blunt-tipped bill that is pale below, and the
lack of contrast in the tertials, I think it is pretty safe to conclude that
this bird is a Wilson's Warbler. Wilson's typically return to Oregon by the
second week of April, not long after the arrival of the first Orange-crowneds.
When I first started paying attention to such things (late 1970's), the average
arrival dates for Wilson's fell around the 17th of April and Wilson's were
exceptionally rare in Oregon during winter. Over recent decades the mean
arrival date for Wilson's seems to have moved forward by about a week and this
species is now found in Oregon in most winters.
Dave Irons
Portland, OR
> Date: Wed, 22 Oct 2014 18:45:00 -0700
> From: linda@xxxxxxxx
> To: OBOL@xxxxxxxxxxxxx
> Subject: [obol] id help needed!
>
> I had the brainwave to put the list of all 148 birds seen on our farm
> since 1977 on my Birds blog with photos. So I am going through old
> photos and came across this one from April 2012 of a warbler, or two
> warblers. My brain seems to be off duty as I cannot tell if this is a
> Yellow Warbler or an Orange-crowned Warbler or something else I'm not
> thinking of. Help, please!
>
> http://lindafink-birdnotes.blogspot.com/2014/10/yellow-warbler-orange-crowned-warbler.html
> --
> http://lindafink.blogspot.com/
> http://lindafink-birdnotes.blogspot.com/
> http://fffwildflowers.blogspot.com/
> http://finkfamilyfarmtrees.blogspot.com/
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