Subject: interior WA crows (fwd)
Date: Feb 25 15:48:11 1994
From: Dennis Paulson - dpaulson at ups.edu

I'm startled that Jerry Tangren can so easily tell breeding from wintering
crows by size. According to Johnston's monograph, in adult males north of
King Co. vs. those from the interior, wing length differs by 20 mm, tail
length by 8 mm, tarsus length by 6 mm, and bill length by <1 mm. In all
cases, the measurements overlap, and these are of course average
differences. First, I don't think I could distinguish birds by size with
differences of that magnitude (Johnston recorded average weight differences
of 8%, with huge overlap), and second, this implies that "Northwestern"
crows have moved all the way across the Cascades and displaced "American"
crows as breeders in the Wenatchee area, but that somewhere nearby there is
a population of "American" crows that move in in the winter. This is really
interesting news but I think needs documenting. I would love to be shown to
be wrong and in fact find out that the situation is more interesting than
we thought. Get people to save road-killed crows, Jerry, and let's measure
them! Record the voices of the breeding and wintering birds--Gene Hunn
would be quite interested in examining the recordings, I imagine.