Gene,

Indeed, I treated Seattle as C.b. in my innocence, before my eyes were
opened to the fine nuances of northwest crow identification. As I said,
the presentation itself refers more carefully to geographic differences
in vocalizations. And your observation is also correct in that nothing
that we have demonstrated argues against a simple clinal variation down
the coast... we need recordings from farther south and farther north to
determine whether the changes continue, or whether there is really a
break here in the Puget Sound region (as we originally interpreted the
data). We hope to make those recordings later this summer... any
suggestions for crow roosts in the Portland to Vancouver Island coastal
area, anyone?

Cheers,
Jim

On Fri, 30 Jun 1995, Eugene Hunn wrote:

> James,
>
> Interesting. But why treat Seattle populations a C. bracyrhynchos? Do
> you have data for Issaquah, Enumclaw, Snoqualmie Pass, Ellensburg,
> Portland, Chehalis, and Olympia? My impression is that all Puget Sound
> area birds were presumed (originally) to have been within the range of C.
> caurinus. The figures you cite seem to reflect the same sort of clinal
> variation reported for the mensural characteristics by David Johnson (if
> I recall his name correctly) in 1960.
>
> Gene Hunn.
>
> On Fri, 30 Jun 1995, James Ha wrote:
>
> > Gene,
> >
> > You might be interested in the abstract (reproduced below) of some work
> > that I'm just starting with my dad (a bioacoustician back east). The
> > paper will be presented at the national Animal Behavior Society meeting
> > week after next. If anyone's interested in the details, I can forward the
> > text and numbers. I'm also presenting a paper (with my graduate student,
> > Renee Robinette) on foraging efficiency and tide height in beach-foraging
> > crows.
> >
> > Oh, and this abstract clearly suggests a stronger species distinctness
> > than appears to be the case. Based on info from tweeters, the presentation
> > downplays the species distinction and just talks about "geographic
> > variation in call characteristics."
> >
> > Cheers,
> > Jim
> >
> > James C. Ha
> > Research Assistant Professor
> > Psychology / Regional Primate Center
> > University of Washington
> >
> > ************
> > SIGNIFICANT DIFFERENCES IN CALL STRUCTURE AMONG PACIFIC NORTHWEST
> > CROW POPULATIONS
> >
> > James C. Ha & Samuel J. Ha
> > Psychology Department, University of Washington, Seattle WA 98195
> > Biology Department, Millersville University, Millersville PA 17551
> >
> > ABSTRACT
> > Vocalizations are frequently used in the identification of
> > Pacific Northwest crows (American Crow, Corvus brachyrhynchos, and
> > Northwestern Crow, Corvus caurinus) in the field. No quantitative
> > study has been made of the geographic variation in these
> > vocalizations. In this study, 26-34 crow roosting calls were
> > recorded from each of four locations: Seattle, NE Olympic
> > Peninsula, San Juan Island, and Nanaimo (Vancouver Island, British
> > Columbia). Discriminant function analysis of five call
> > characteristics was used to provide a quantitative method for
> > categorizing calls. One hundred percent of calls from distinct C.
> > brachyrhynchos (Seattle) and C. caurinus (Nanaimo) populations were
> > correctly classified. Eighty one percent and sixty five percent of
> > Olympic and San Juan Island calls, respectively, were classified as
> > C. caurinus calls, indicating an area of geographic overlap. This
> > overlap may be due to genetic hybridization in calls, environmental
> > effects of early exposure to the calls of both species, or simply
> > sympatric overlap in species ranges (mixed species flocks).
> >
> >
> >
> > On Fri, 30 Jun 1995, Eugene Hunn wrote:
> >
> > > The rictal bristle "field mark" was mentioned, I believe, in some bird
> > > banders handbook. We field tested it when we learned of it but found it
> > > to be unreliable. Likewise unreliable on museum skins. An exchange on
> > > this topic was published in WOS Notes by Ian Paulsen et al. As for the
> > > number of transverse muscles across the syrinx. What is the sample
> > > size? Are crow vocalizations so discretely two-valued? They seem to
> > > have quite a range of vocalizations to my ear, including pitch, quality,
> > > and pattern.
> > >
> > > Gene Hunn.
> > >
> > > On Thu, 29 Jun 1995, Michael Price wrote:
> > >
> > > > Hi Tweets,
> > > >
> > > > I heard somewhere (don't remember where) that there are only two significant
> > > > differences between Northwestern Crow (NOCR) and American Crow (AMCR): one
> > > > is anatomical, that NOCR has 4 bands of transverse muscle across its syrinx
> > > > where AMCR has only 3, hence its deeper voice; the other, that rictal
> > > > feathering is species-diagnostically different.
> > > >
> > > > Anyone know yea or nay to these things?
> > > >
> > > > Michael Price
> > > > Vancouver BC Canada
> > > > michael_price at mindlink.bc.ca
> > > >
> > > >
> > >
> >
>