Re: Orange-crowned Warblers

Peter Pyle

A bit of caution on presuming that juvenile Orange-crowneds equate to
local breeding: they are a "molt-migrant" species. For our local
coastal-breeding lutescens many juveniles and adults leave breeding
grounds soon after the fledge date and fly up into the high Sierra to
molt. On the Farallones we have recorded juvenile OCWAs (reverse migrant?)
as early as June 6th (Western Birds 22:80). Dominik's Bercut juvenile was
probably a molt migrant and the Mt. Davidson juveniles could have been as
well, not to say that they may not have been locals as well. If they were
still be attended by the adults it would be better evidence for local

Some further information on Orange-crowned Warbler juvs. with wing bars

The CCSF web server suffered a power failure and has been sporadic today,
but seems to be working now.

On Thu, 6 Jun 2013 13:41:35 -0700 (PDT), Dominik Mosur
<polskatata@...> wrote:

Just to add to Paul's notes, my experience on Mt. Davidson has been
similar to his in the past three springs (2011-13): consistently singing
on territory from mid/late March through early May, then nothing until
late May/early June when two of the three years a "wing-barred" juv would
suddenly appear.. I did observe a singing male copulating w/a female in
mid/late April in either 2011 or 2012 but that's the closest to a
confirmation. To add to the confusion, Orange-crowns fledge and begin
dispersing early; I had one at Bercut on Tuesday for example in what
doesn't even remotely resemble nesting habitat after not seeing a single
one on the BBS the day before.

Also to clarify Cedric's paraphrasing of what I told him this morning: I
told him that his sighting was probable confirmation of a species rarely
confirmed nesting in the City. I had an Orange-crowned Warbler carrying
food to a nest in the West Wash/For Miley last year and I believe Josiah
confirmed nesting during his surveys of Mt. Sutro (not by coincidence in
the Rotary Meadow where native plants have been restored might I add,
then only place on the mountain not CHOKED OFF by eucalyptus and ivy)

Additional food for thought RE nesting Orange-crowned Warblers from DAVID
SUDDJIAN in Santa Cruz County:

"A family of ORANGE-CROWNED WARBLERS with fledglings at Peery Park along
Soquel Creek was unexpected. Here's why; the past three springs I have
had the species singing there regularly from their early spring arrival
until late April, then usually no further detections until after the
nesting season. That pattern seemed to hold this season with regular
detections of (usually) one singing bird from March 18 to April 8, and
then a singing bird on May 2, but none detected after.Until May 24 when I
was surprised to have an agitated pair acting as if a nest with young was
nearby, right at the spot where I begin every visit to Peery Park. And
then on May 30 there was a family group in the same spot. So assuming
they nested right at that spot, which seems reasonable, I conclude the
species went nearly completely undetected during the nesting effort! "

Dominik Mosur
San Francisco
Joseph Morlan, Pacifica, CA
"It turns out we're very good at not seeing things" - Jack Hitt

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