[Tweeters] Fwd: Townsend's Warbler fine print

Robert O'Brien baro at pdx.edu
Wed Dec 15 17:28:59 PST 2021

---------- Forwarded message ---------
From: Robert O'Brien <baro at pdx.edu>
Date: Wed, Dec 15, 2021 at 5:28 PM
Subject: Townsend's Warbler fine print
To: Robert O'Brien <baro at pdx.edu>

Here is the entire discussion on ID Fronters

Robert O'Brien <baro at pdx.edu>
Sat, Apr 3, 12:59 PM
to BIRDWG01, bcc: obol, bcc: Matthew, bcc: Chris, bcc: patrick, bcc: me

To: ID Frontiers

I'm curious about the 'crown stripe' on this Townsend's Warbler
photographed 03/21/2021 in Newport OR.

Must be a wintering bird as likely too early for a migrant.

Some years ago Townsends wintering in Oregon were assigned as breeders from
the Queen Charlotte Islands, BC
I also wonder about the current acceptance of this distribution.

A detailed discussion of ageing of Townsend's and Hermit Warblers is here
If I am reading Table 2 correctly, no stage of Townsend's plumage should
show yellow in the crown (Score = 8 in Table 2), but maybe I misinterpret.
I find few if any such birds in the Macaulay Library, but I did not check

Would this make it a Hermit Warbler intergrade? There doesn't seem to be
much else to indicate Hermit Warbler? Is it a transitional molt stage?
Hopefully Mr. Pyle might comment? Thanks to all for any assistance.

Bob OBrien Portland OR

Andy Thomas <adt0611 at yahoo.com>
Sat, Apr 3, 2:07 PM
to birdwg01 at listserv.ksu.edu, me

I see a similar pattern in some of the wintering Townsend's Warblers that
come to my feeders; greenish crown with black borders. My assumption has
been that they are juvenile males molting into adult plumage.

Andrew Thomas
West Linn (Clackamas)

Allen Chartier <amazilia3 at gmail.com>
Sat, Apr 3, 3:26 PM

I have no expertise with that hybrid, but I don't see any yellow in the
crown. I see green.

Archives: https://listserv.ksu.edu/birdwg01.html

Wayne Hoffman <whoffman at peak.org>
Sat, Apr 3, 8:26 PM
to me, BIRDWG01

Hi -

The throat pattern indicates that this bird has not completed molt into
definitive alternate plumage. Therefore it is likely that the greenish
center to the crown is not-yet-replaced basic feathering, and likely
within a week or two will be replaced with black feathers.

Wayne Hoffman

From: "baro at pdx.edu" <baro at pdx.edu>
To: "BIRDWG01" <BIRDWG01 at listserv.ksu.edu>
Sent: Saturday, April 3, 2021 3:59:49 PM
Subject: [obol] Townsend Warbler 'crown stripe' ?

Robert O'Brien <baro at pdx.edu>
Tue, Apr 6, 1:16 AM
to Wayne, BIRDWG01, bcc: Matthew, bcc: Chris, bcc: Roy, bcc: Darrel, bcc:

Thanks to all for their comments that are very helpful. Especially to the
located-nearby AndyThomas who has seen similar plumage at his feeders.. I
don't claim to know anything about plumage or molt sequence, or very much
else. Just a lifelong interest in birds.
I've always had an odd color perception. I would interpret the crown
center as yellow-green but will yield to green as unanimously noted.
And the warbler is clearly in molt which is why I included the throat photo.
But maybe there is more to this than my amateurish perception. Or not.
Does this imply a molt sequence in which the crown feathering proceeds
systematically inward from the extremities towards the center, rather than
simply replacing the crown feathering 'randomly'. Does such orderly
procession occur in other species? If at all?
Note that the throat feathering on this individual DOES seem to be replaced
Further, there is the question of molt sequence seasonality. Do the
wintering Townsend's in Oregon actually come from the Queen Charlotte
Islands as suggested here? https://www.jstor.org/stable/1367976?seq=1
If so, do these shorter distance migrants(?) have a different molt sequence
than the others?
Now these birds were separated by shorter wing chord length which could be
interpreted in simplicity as being due to selection for shorter migratory
flights as opposed to other pressures. And if this 'race' is indeed a
'race', e.g. subspecies, then might it have a different molt sequence? So
far as I know, these birds were not ever given subspecies status, which was
NOT even suggested (yet) by the authors of the above paper, pending further
Lingering questions, As this particular warbler has sucked me in.
Bob OBrien Portland OR
PS I'm still trying to understand all this but it seems that all
passerines have NOT 2-year plumages, as I had naively assumed, but some
have 3-year. Is this correct, at least for Townsend's/Hermit Warblers?
P.P.S. I still haven't studied Macaulay rigorously but below are a few
additional photos.. Note the first entry in October. Too early for molt?.
And the 7th entry which is 'too cool' and may be significant in this
P.P.P.S. Growing up on the San Francisco Peninsula I have always cringed
at the designation of San Francisco et al. as 'Northern' California. I
would call it Central California with Northern California being, e.g. Del
Norte County etc. But I conform more or less below.
P.P.P.P.S. I designated 'Immature' in my eBird search and those appear
below. BUT eBird volunteer reviewers cannot review every single photo so
some discretion must surely be applied to interpreting these photos' age
class. The last entry below is especially interesting as to age class. But
as an extreme vagrant may not be 'typical'

Month Locale Crown Photo/Checklist url
Oct S. CA 'crown stripe'
Oct S. CA mostly all dark
Oct S. CA All dark
Aug BC all very dark
Oct S. CA All dark
Dec S. CA All dark
Aug WA all very dark YOU _MUST_ CLICK ON THIS
Mar S. CA All dark crown mostly molted throat?
Mar S. CA All very dark crown all yellow throat! WOW!
Jan MA !? first winter?

mitch at utopianature.com
Sun, Apr 11, 8:11 PM
to me, BIRDWG01

Hi Bob, and all,

I had a thought on this that might be of value. An example of this
'by the feather tracts' molt progession in crown is visible in first
spring White-crowned Sparrow (at least some, sometimes). In what little
I have paid attention, it seems like when first spring White-crowns
molt their brown crown stripes out, and the black stripes replace
them, you might be able to see this.

In the last two I saw, one today, one last year or year before (which I
have a pic of), both had the two lateral crown stripes pitch jet black,
the two dorsal crown stripes were still brown as typical first winters.
The black lateral stripes (eye to nape) were 'stem to stern' completely
devoid of any trace of any brown feather. The dorsal brown stripes
were equally devoid of any trace of black. Right now is the time to
see this, and of course viewing it is over in a couple or few weeks.
For me, by time it starts showing, I have run out of White-crown time
for the year and am distracted with colorful little objects zipping
around up in trees with zippy songs.

Might be something you could look for right now as they pass by
going north. I am way far south and we generally lose them early,
mostly before we see this. I would have to look and see if the
buff stripes had gone white on the one I photo'd.

How do White-throats progress?

Things with stripey heads would be where to look for this.

Mitch Heindel
Utopia, Texas

On 2021-04-06 01:16, Robert O'Brien wrote:

> Does this imply a molt sequence in which the crown feathering proceeds

> systematically inward from the extremities towards the center, rather

> than

> simply replacing the crown feathering 'randomly'. Does such orderly

> procession occur in other species? If at all?


>> Bob OBrien Portland OR


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