If you're interested in the western Washington crow situation you should
read D. W. Johnston's The Biosystematics of American Crows (Seattle,
University of Washington Press, 1961). He concludes based on measurements of
all breeding season crow specimens in NA collections that they increase
clinally in all measurements as one moves south from Vancouver Island to the
Columbia River, and thus recommends that they be treated as subspecies of
the American Crow. For some reason, the AOU committee has discounted
Johnston's research.

I, too, have seen flocks of crows on the beaches that looks small, but I've
never been able to convince myself that they sounded any different than any
of the thousands of crows that inhabit Western Washington from the foothills
to the coast and from Canada to Oregon. Crow vocalizations are highly
varied, and the alleged lower pitch of the Northwestern crows would have to
be judged by comparing the same type of vocalizations, and would probably
require hundreds of carefully documented tape recordings during the breeding
season to establish a consistent difference. I've seen no evidence that
there are two distinct populations of crows in Western Washington (and there
are crows now all along I-5, up and over to Ellensburg), much less any
reason why there should be one species confined to the outer coast of the
Olympic peninsula and the shores of the Straits of Juan de Fuca and Puget
Sounds that is magically replaced by another species at Ocean Shores and
Issaquah. One crow I picked up dead in my neighborhood near Green Lake in
Seattle measured precisely intermediate. If someone comes up with a
convincing, controlled DNA analysis that proves there are two genetically
distinct populations cohabiting here, I'll believe it, but not until. I
believe the two crows were originally split on the analogy of the Fish Crows
of the Atlantic coast, but the geological context here is quite different,
and I have little trouble picking out Fish Crows by call.

Gene Hunn, Seattle, hunnhome at accessone.com