[Tweeters] RE: [OBOL] Acorn Woodpeckers all the way to Seattle!

Wayne Weber contopus at telus.net
Fri Oct 1 09:48:03 PDT 2010

Dave and Oregon Birders,

I would agree that birders looking for unusual occurrence trends should look
beyond just the current season, and look for long-term trends. Thanks for
putting together the various NAB comments about Acorn Woodpeckers over the
last few years.

However, one should also look beyond one's own region, as well as beyond the
current year. In British Columbia, which had only two records of Acorn
Woodpecker prior to 2010, there were two more sightings within the same week
in May 2010: one (a single-day sighting) at Manning Provincial Park, and
another present for several days at Princeton. These were unquestionably
different birds, because ACWOs were seen in both places on the same day.

Taken together with extralimital sightings of Acorn Woodpecker in WA, it is
apparent that, even if there is an accelerating trend of extralimital
sightings of Acorn Woodpecker (a species not known for extralimital
occurrences) in recent years, that trend seems to have hit a new high in

This increasing trend of extralimital occurrences may not have anything to
do with acorn crops, but it likely does have a logical explanation (as
opposed to pure chance), and it would be intriguing to know what that
explanation might be.

Without speculation, there can be no advances in science, but speculation
alone can lead to erroneous conclusions. Dennis, thanks for speculating

Wayne C. Weber

Delta, BC

contopus at telus.net

From: obol-bounces at oregonbirds.org [mailto:obol-bounces at oregonbirds.org] On
Behalf Of David Irons
Sent: October-01-10 1:33 AM
To: OBOL obol
Subject: Re: [OBOL] Acorn Woodpeckers all the way to Seattle!

Greetings All,

I will use this thread as an opportunity to shamelessly plug North American
Birds (NAB). As many of you know, I am the senior regional editor (Oregon
and Washington region) for this fine and venerated journal. In this role I
am charged with compiling interesting bird sightings within our region,
summarizing them and, most importantly, providing some sort of longer term
context that helps the reader understand why a particular sighting or group
of sightings is significant. Over time, by following the seasonal reports
that appear in this journal one comes to learn that virtually no individual
sighting or group of sightings exists in a temporal vacuum.

Today's thread about Acorn Woodpeckers is a classic example of folks seeing
a report or two and concluding that something completely different is
happening this season or this year and failing to recognize that these
recent events are part of a long-term phenomenon and not just a one-year
wonder. The extralimital dispersal of Acorn Woodpeckers (particularly in
Fall) has been going on for several years now. Why this is happening is
anyone's guess, although I offer one speculative idea in the "S.A."
published in the 2009 Spring Report (see below). What follows is a sample of
some of the comments about wandering Acorn Woodpeckers that have appeared in
the Oregon and Washington NAB columns in recent years.

Spring 2010 Report:
Coos 25 Apr (TR) was the first in that county in 20 years, while another at
Olympia 16 May (fide CW) was just the 6th for w. Washington. Additional
singles at West Linn, Clackamas 16 Mar (M. Reese, J. Allen) and Sauvie I. 29
May (D. Mandell) were merely short distance strays.

Summer 2009 Report:
Yet another Acorn Woodpecker wandered e. of the Cascades, where formerly
extremely rare; this season's bird inhabited Malheur N.W.R. 1-14 Jun (C.
Chutter et

Spring 2009 Report:

Start S.A.("S.A." -- used to direct special attention to a developing
pattern or unusual combination of events)

Yet another Acorn Woodpecker, this one at Bend 21 May (D. Fagan), wandered
east of the Cascades. This is just the second-ever spring season bird away
from the Region's known colonies; most extralimital reports have come
Sep-Nov. Prior to 2003, there were about 12 records from e. Oregon (Birds of
Oregon: A General Reference 2003) and just one Washington record away from
the isolated outpost at Lyle, Klickitat. Since then, 8 more Acorns have been
detected east of the Cascades, 2 in Washington and 6 in Oregon (includes one
from June 2009) and there have been 3 in w. Washington, where none had
occurred prior to 2005. By most accounts, Acorn Woodpeckers are declining
across much of their range, particularly in California where fungal disease
("Sudden Oak Death") is taking a heavy toll on several oak species and other
mature stands are failing to regenerate (Eric Walters pers. comm.). One must
wonder if these strays are prospectors from local populations, or perhaps
refugees from farther afield.

End S.A.

Fall 2008 Report:

Acorn Woodpeckers occasionally stray just e. of the Cascades, particularly
into Klamath, thus one at Klamath Falls 18 Aug (DH) was only moderately
out-of-place. However, an Acorn at Frenchglen, Harney 23 Sep (G. Grier) was
just the 2nd for se. Oregon; another was at Frenchglen 22 May 2004.

Fall 2007 Report:

An Acorn Woodpecker at Oakville, Grays Harbor 12-16 May was about the 5th
for w. Washington (ph. P&RS); after approximately 15 years of being
restricted to a small portion of Klickitat, Acorn Woodpeckers, since 2005,
have popped up at seemingly random locations statewide.

Fall 2006 Report:
Acorn Woodpeckers continued to wander this fall: one remained at Ft.
Simcoe, Yakima to 13 Aug (DG), while singles appeared near Cheney, Spokane 8
Sep (M&F Stout) and W. Bunch Field, Jefferson 3 Oct (C&G Bartlett); the only
more nw. record comes from near Vancouver, British Columbia 15 Jun 1996. In
Oregon, an Acorn wandered e. to Upper Klamath L. 1 Oct (J. Van Moorhem).

After reading the various commentary above, I hope it is apparent that this
season's reports of stray Acorn Woodpeckers align with an ongoing pattern
and not a one-year anomaly. In addition to the long-distance wanderers,
there have been many local birds showing up in places where they have not
been traditionally present. Although I've not seen an Acorn Woodpecker far
out of range, I had one fly through Amazon Park (in southeast Eugene), while
watching a soccer game my daughter was playing in when she was still in
middle school (at least six years ago). Last spring (2010) I had an Acorn
Woodpecker near the summit of Skinner Butte, a site I had birded many, many
times without previously encountering this species. More recently, the local
Weds. morning group found two Acorns at Skinner Butte.

I would encourage folks to resist viewing this season's sightings from a
short-term perspective. Endeavor to examine such sightings in a longer term
context. If understanding these sorts of trends and looking for ongoing
patterns appeals to your intellectual curiosity about birds, I would
strongly recommend a subscription to North American Birds. I learn something
from every column I write and benefit from the commentary offered by the
other editors, both in our region and in other parts of North America.

Dave Irons
North American Birds Regional Editor (Oregon and Washington Region)
Eugene, OR

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