[obol] Re: id help needed!
- From: David Irons <llsdirons@xxxxxxx>
- To: "linda@xxxxxxxx" <linda@xxxxxxxx>
- Date: Thu, 23 Oct 2014 09:51:02 -0700
Linda et al.,
The usefulness of specific date and location are often unestimated clues when
identifying mystery birds. Like Lars, as soon as I saw the budding tree
foliage I knew it probably wasn't a Yellow Warbler.
For those that own it, the Peterson "Warblers" guide by Jon Dunn and Kimball
Garrett has wonderful plates that show only the undertail and undertail coverts
of all the North American warblers. I can't remember who said it, but someone
is quoted as saying these are the most useful plates found in any North
American field guide. I can't disagree.
Dave Irons
Portland, OR
Sent from my iPhone
On Oct 23, 2014, at 9:39 AM, "Linda Fink" <linda@xxxxxxxx> wrote:
> Wow!! Thanks so much, Dave, for the detailed analysis. I have learned that
> crummy photos are a good way to teach me to look at more than the obvious
> field marks. As for the date of the photo, it was taken April 23. We are
> about 2 weeks later than Salem here in the Coast Range. We can watch the
> seasons changing in the spring as we drive from Grand Ronde to Salem. Yellow
> warblers, do, now that you mention it, show up much later here than do
> Wilson's.
>
> We have many Wilson's Warblers here on our farm, seasonally, so that makes a
> great deal of sense. I confess that I mostly identify "yellow" warblers by
> voice and have not paid that much attention to obscure (to me) field marks.
> You have educated me greatly and I appreciate it!
>
> Linda
>
> On 10/22/2014 11:17 PM, David Irons wrote:
>> 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/ (formerly/Vermivora/) 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
>
> --
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> http://lindafink-birdnotes.blogspot.com/
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> http://finkfamilyfarmtrees.blogspot.com/
>
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