Tweets,

There was a careful study done in the late 1950's which concluded that all
measurements (of specimens of adult crows collected during the breeding
season) increased clinally from the Victoria, BC area as you move south
through Puget Sound to the Columbia River (David W. Johnston, The
Biosystematics of American Crows_, University of Washington Press, 1961).
Johnston, however, did not analyze vocalizations systematically and his
research was done before modern DNA analysis was possible. For whatever
reason, the powers that be (the AOU checklist committee) have chosen to
disregard the results of that study, maintaining the Northwestern Crow at
the species level. For historical interest, it hasn't always been recognized
as a distinct species. In fact, W.L. Dawson in his classic _The Birds of
Washington_ (1910) heaped scorn on those (East Coassters) who jumped to the
conclusion that the Northwestern Crow was a species on the analogy of the
Fish Crow. The evolutionary histories of the two cases are quite
differerent, in large part because the geological/glaciological histories of
the Pacific Northwest are very different from that of the Atlantic coast
(the Fish Corw apparently evolving in the Caribbean; the Northwestern Crow
most likely isolated for a much shorter time in an ice-age refugium). The
fact that the great majority of local birders and ornithologists have given
up trying to distinguish two sympatric crow species in the Pacific Northwest
while the experts on the AOU committee, who have much less experience in
this area, affirm its species status may explain why the two have not yet
been lumped. I remain open to being convinced otherwise if and when I see
some evidence to support the idea that there are two species of crows here.

Gene Hunn.



----- Original Message -----
From: "Michael Hobbs" <Hummer at isomedia.com>
To: "Tweeters (E-mail)" <TWEETERS at u.washington.edu>
Sent: Tuesday, June 12, 2001 1:26 PM
Subject: Re: "Northwestern Crows" (from Burt Guttman)


> Denny - I think the real question here is "How can you tell?" On what
basis
> should we write down "American Crow" versus "Northwestern Crow", even if
we
> *do* believe there are more than one species?
>
> What field marks do we need to observe? Or what habitat is essential? Or
what
> geographic boundaries need to be crossed?
>
> I think it's pretty clear that the vast majority of urban Seattle crows
are
> American and not Northwestern. If I recall correctly, the original
reference
> was to crows slightly north of Seattle (correct me if I'm wrong). Given
that
> there *may* be some Northwestern Crows along the beaches north of Seattle,
it
> is appropriate to question an identification to species of the crows
involved.
>
> I personally *think* I've seen and heard a difference between the crows in
Neah
> Bay and the crows in Redmond, and I call the former "Northwestern Crow".
But
> if one of those showed up in my yard in Kirkland, I doubt I could tell.
>
> I guess we ought to be calling them "Crow sp." unless there is reason to
> believe otherwise, and if there IS reason to believe otherwise, we ought
to be
> prepared to explain.
>
> == Michael Hobbs
> == Kirkland WA
> == hummer at isomedia.com
>
> ----- Original Message -----
> From: <osprey at nwinfo.net>
> To: <TWEETERS at u.washington.edu>
> Sent: Tuesday, June 12, 2001 12:34 PM
> Subject: Re: "Northwestern Crows" (from Burt Guttman)
>
>
> > We can't go through life making our own rules. We have to follow some
sort
> > of order in our activities. As far as the activity of birds and
birding,
> > the AOU is the (or "a") governing body. Until someone provides them
with
> > scientific documentation that shows for certain that American and
> > Northwestern Crows are the same species, and they make that change in
the
> > list, it seems to me that we should follow their list as it stands.
> >
> > The fact that "most ornithologists in this area" might believe the crows
are
> > of the same species doesn't matter unless they are proving it with
> > scientific research. There used to be a lot of experts who thought the
> > world was flat until "research" proved them wrong. Lets let the
research
> > prove this case. I understand that several studies are underway and
> > hopefully we won't have to wait much longer for the results.
> >
> > It does seem odd, though, that many of the birders who don't list the
> > Northwestern Crow will include it on a Big Day or Birdathon list for
enhance
> > the numbers.
> >
> > Denny Granstrand
> > Yakima, WA
> > * * * * * * * * * * *
> >
> >
> >
>