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
> >
> >
>