Susan, I think your description ruled out both accipiters and harrier, and
all I can say is that there ain't no such bird--so calling it "Susan's
Hawk" is appropriate.

If you start from first principles, your bird could only have been a heron,
hawk, or owl, from the large size, rounded wings, and slow, steady flight.
Banded tail would seem to rule out heron. Daytime flight makes owl less
likely but not impossible. Two white bands at tail base rules out
everything that's native here. No way you'd describe the wingspread of a
Sharp-shinned Hawk as 3', and I doubt if you'd even use that figure for a
Cooper's. From the description I can't see it as any of the buteos that
might normally occur here. The tail narrowing sharply doesn't seem to work
for any of them, which should be flying with sides of tail more or less
parallel.

I wonder if it might have been an escaped raptor of some kind. Anything
gone from the zoo lately, Mike?

Alternatively, any chance of any of your descriptors being wrong, Susan?
Maybe wings not buff underneath? Maybe tail banded otherwise? How big did
it look in comparison with a crow? So much of this sort of thing depends
on exact (read: absolutely accurate) observation of specific field marks,
just as I wrote last week, that "a miss is as good as a mile" applies here.

Dennis Paulson, Director phone: (206) 756-3798
Slater Museum of Natural History fax: (206) 756-3352
University of Puget Sound e-mail: dpaulson at ups.edu
Tacoma, WA 98416