Re: Sunset bird question...

Alvaro Jaramillo
 

Folks



I have a real interest in yellowthroats. For an as of yet unfinished San
Francisco Bay Bird Observatory project I measured and analyzed hundreds of
specimens of our local breeding (Salt-marsh, or San Francisco Bay)
yellowthroats, and various other western subspecies (the migrants we see
here). The local breeders are an endemic, not regularly found outside of the
Bay Area other than a few which may disperse to the south in winter. The
locals, sinuosa, are rather small and petite birds with little bills, short
wings and relatively short tails. They are one of the smallest local
warblers, while the migrants seem heftier, longer-winged and don’t look
particularly small in the field. The locals are very olive, particularly on
the crown, and the flanks can look olive-brown. The white diadem is not
super well developed in the spring, although it gets larger and more
noticeable through wear and fading in summer. The yellow coloration of our
locals is not as bright as that of the migrants, it is just kicked down a
notch in brightness. The migrants on the other hand often have a greyish
tone to the crown, and much less of an olive look altogether. The flanks are
paler, and often greyish, not olive-brown. Furthermore they show more lemon
yellow underparts, and often more extensive yellow on the underparts. Some
migrants which will sing while they are moving through have a more complex
song, sort of like a mix of Common Yellowthroat and McGillvray’s Warbler. It
is all finicky little differences, but with some attention to the details,
the two groups can be identified in the field.



Cheers



Alvaro



Alvaro Jaramillo

HYPERLINK "mailto:chucao@..."chucao@...

Half Moon Bay, California



Field Guides - Birding Tours Worldwide

HYPERLINK "http://www.fieldguides.com"www.fieldguides.com

_____

From: SFBirds@... [mailto:SFBirds@...] On Behalf Of
Dan Singer
Sent: Friday, May 30, 2008 10:51 AM
To: SFBirds@...
Subject: Re: [SFBirds] Sunset bird question...



Another possibility is that your bird was simply a straggling migrant. Given
that your yard is probably not a good breeding site, this might explain its
presence in your neighborhood.

Dan Singer

----- Original Message ----
From: Dan Murphy <HYPERLINK "mailto:murphsf%40yahoo.com"murphsf@...>
To: HYPERLINK "mailto:SFBirds%40yahoogroups.com"SFBirds@...;
Siobhan Ruck <HYPERLINK
"mailto:siobhanruck%40mindspring.com"siobhanruck@-mindspring.-com>
Sent: Friday, May 30, 2008 9:52:33 AM
Subject: Re: [SFBirds] Sunset bird question...

Siobhan,
The only place that's likely to have adult yellowthroats in SF right now is
Lake Merced.&nbsp; Pine Lake is very unlikely because it hasn't recovered
from the restoration project yet.&nbsp; Almost all GGP records are for non
breeding birds.&nbsp; The breeding bird atlas confirmed nesting at LM, but
nowhere else in SF.&nbsp; Since this species establishes breeding
territories as early as February, it is quite possible you got a male that's
moved on from LM.&nbsp; I had one on top of the mesa by the Sunset Circle a
week ago.&nbsp; It was singing, but moving so much it apparently wasn't on a
territory.&nbsp; On the other hand you might have picked up a migrant headed
north.&nbsp; That's a very cool yard bird for the mid Sunset District.

Best,
Dan Murphy

--- On Fri, 5/30/08, Siobhan Ruck <siobhanruck@ mindspring. com>
wrote:
From: Siobhan Ruck <siobhanruck@ mindspring. com>
Subject: [SFBirds] Sunset bird question...
To: SFBirds@yahoogroups .com
Date: Friday, May 30, 2008, 7:22 AM

Thinking at first that my neighborhood mockingbird had learned a new

song, I was surprised to see a male Common Yellowthroat in my yard this

morning. I'm at 28th and Pacheco, and can't figure out where he might

have come from - the closest appropriate spot for him would seem to be

GGPark or Pine Lake Park. Does anyone know of any other nearby

locations that might be home to a COYE?

It was certainly a nice surprise to start the day.

Siobhan Ruck, SF

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