Maureen 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...........


then Dennis wrote -

>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 is right, of course, a California Gull is quite brownish in
1st-summer plumage and remains distinct through moult into 2nd-winter.
I glossed over this point when reading your first post. The overall
grayness does favour Ring-billed over California or even Mew
which is also browner in tone. 1st-summer Californias often even have a
few golden hints to the mantle in their first plumage, while
freshly-plumaged juv. Mews have a purplish-brown sheen to the head which
is really quite lovely. This wears off rather quickly, though. The
difference in carriage I wrote of the first time is noticeable with
practice, with Californias carrying the "head high-tail low" much
more so than Ring-billed. You already have eliminated Mew based on bill
size. Another couple of points to differentiate Ring-billeds and Mews: a
bird-of-the-year Ring-billed will have a neat, crisp blackish subterminal
band on the tail while a Mew Gull of the same age will have a tail band
which is more diffuse and wider. The most consistent "killer field mark"
for 1st-summer Ring-billed versus Mew is that the brownish inner markings
on the wing coverts extend downward toward the ends of the feather in a
sharp point, versus the softer scalloped U-shaped markings of Mew Gull on
the same feathers. These coverts are easily visible when the bird is on the
ground walking around. Good luck!

- Jack Bowling
Prince George, BC
jcbowling at mindlink.bc.ca