Size is the key here, isn't it? As I understand the grouping in the
guides, the CA gull is the "smallest" of the large gulls, while the
ring-billed is about the largest of the small gulls. We're talking about
L=17" vs L=16" on these two species. My "mystery" juveniles seemed a tad
smaller than the obviously older CA gulls nearby, but not much. I'm going
to take another look at these if enough light this evening after work.
This is keeper info to print out for certain. Thank you very much.

Whew, Maureen E2 me2 at u.washington.edu and Des Moines WA
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On Tue, 3 Sep 1996, Dennis Paulson wrote:

> >The long dark brown to blackish brown wings did appear to be "heavy" as
> >these birds walked around. I got very close (3 meters) and very long
> >(30-45min) gawkings at the Des Moines Marina gulls. Dennis thinks maybe
> >these are 1st year ring-billeds; and Jack below suggests 2nd year CA's.
> >This decision should be simpler, but according to combined info, these are
> >California/ring-billed hybrids! They are not glaucous-winged, mew,
> >western, Bonaparte"s, Heermann's or Herring's. As of late afternoon,
> >09-03...........
>
> Maureen, only first-winter CAGUs and RBGUs have bubblegum-pink legs and
> bill base, but CAGUs are entirely brown, while RBGUs are quite pale, gray
> above and white below. Second-winter CAGUs already have greenish legs and
> duller bills, as well as an entirely gray mantle with no scalloping. RBGUs
> have wings just as long as those of CAGUs; they're similarly shaped. It
> sounds as if you thought they were closer in size to Californias; I don't
> know what to make of that.
>
> 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
>
>
>