Bob,
I really appreciated your synopsis of the large gull thread that has been
going on. Without more concrete research, none of these questions can
truely be answered and even then we ultimately just create more questions.
To answer your questions regarding the Glaucous-winged Herring hybrids,
the birds cover the entire range from appearing almost pure in both
directions. Often it is just a case of having the wrong colored iris or
some other small trait that doesn't fit. As for the wintering location of
these birds, band recoveries of winter birds were found the length of the
Pacific coast with the bulk of the sightings in the San Francisco Bay
area. We could all benefit from more closely examining concentrations of
gulls in good light. Good Luck.

Todd Eskelin
astde at uaa.alaska.edu