Subject: [Tweeters] Northwestern Crows
Date: Jun 19 14:33:32 2012
From: Eugene Hunn - enhunn323 at comcast.net
Tweets,
On what I sometime ago called the "Myth of Two Crows," it takes more than
one or two apparent distinctions to justify a species distinction. Though
DNA and splitting are now the in-thing, there have been overzealous splits,
e.g., Western Flycatcher, that would not have been made had the lead
scholars been more casreful in documenting the full range and pattern of
variation between the extremes. I understand that the "Western Flycatchers"
have been shown to constitute a single geographical variable species, linked
clinally across a 400 miles zone.
In the case of the "Northwestern Crow," while crows from the Kenai Peninsula
to the outer Olympic Peninsula may vary little, there is no clear boundary
between those crows and the mass of crows throughout western Washington. The
ecological preference for beach foraging could simply be due to where the
available crow foods are to be found along the densely forested outer
coasts. If there are really two crow species in western Washington there
should (or perhaps "must") be a zone of contact, of sympatry, where one
could demonstrate the coexistence of two distinct species populations.
A few mitochondrial DNA differences proves nothing about how the crows
throughout western Washington interact, with each other and with the
environment. Has anyone done a comprehensive study of vocal patterns (of
breeding birds) throughout the region. If so, can they demonstrate that
there are two sympatric vocal systems in play? Or, would such a study show a
clinal pattern of variation linking the extreme outer coastal call types
with the calls further south along the coast and/or inland, as with the
"Western Flycatchers"?
I remain highly skeptical of the "Myth of Two Crows," lacking some more
definitive data.
Gene Hunn
Petaluma, CA
From: tweeters-bounces at mailman1.u.washington.edu
[mailto:tweeters-bounces at mailman1.u.washington.edu] On Behalf Of Louise
Rutter
Sent: Monday, June 18, 2012 8:14 PM
To: tweeters at u.washington.edu
Subject: RE: [Tweeters] Northwestern Crows
Voice has a lot to do with it. I spent a lot of time listening to the small
crows on the beaches of the northwestern Olympic peninsula before I called
them north-western. There is a very distinctive sound to the crows in that
area.
Louise Rutter
Kirkland
From: tweeters-bounces at mailman1.u.washington.edu
[mailto:tweeters-bounces at mailman1.u.washington.edu] On Behalf Of Nigel Ball
Sent: Monday, June 18, 2012 2:00 PM
To: TWEETERS
Subject: [Tweeters] Northwestern Crows
Hi,
What exact criteria do TWEETERS birders use for distinguishing Northwestern
Crows in Washington state? It's a problem that's been bothering me for some
time, and I'd love to know what others think...
Also, are there ebird/ ebird reviewer rules on this?
Cheers,
Nigel
Bainbridge Island
Nigel.ball at gmail.com