James,

It's about time someone look at this issue systematically. I'm open to
whatever conclusion the data indicates, though I'll feel silly if we've
missed a "good species" all these years.

Gene.

On Mon, 3 Jul 1995, James Ha wrote:

> 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
> > > > >
> > > > >
> > > >
> > >
> >
>