Herring Gull – Larus argentatus – also known as Сребристата чайка (Bulgarian), Sølvmågen (Danish), Silbermöwe (German), gaviota argéntea (Spanish), Harmaalokki (Suomi / Finnish), Goéland argenté (French), ezüstsirály (Magyar / Hungarian), gabbiano reale nordico (Italian), zilvermeeuw (Dutch), Mewa srebrzysta (Polish), gaivota-prateada, gaivota-argêntea (Portuguese), Gråtrut (Swedish).
Ring-Billed Gull – Larus delawarensis – also known as Goéland à bec cerclé (French), Ringsnavelmeeuw (Dutch), Ringschnabelmöwe (German), Gavina americana (Italian), Gaviota de Delaware (Spanish), and Ringnäbbad mås (Swedish).
The first two pictures show the much darker 1st Winter Herring Gull set against a backdrop of Ring-Billed Gulls. Adult Herring Gulls have the gray back and black wing-tips like the adult Ring-Billed, but unlike the Ring-Billed Gulls, who have a black ring around their bill, adult Herring Gulls have a red spot on the bottom bill (bottom picture is all adult Ring-Billed Gulls, except the top right bird, which is an adult Herring Gull).
Young Herring Gulls and young Ring-Billed Gulls, however, differ in appearance – Herring Gulls are much darker. As for distinguishing between a 1st Winter Herring Gull and a 2nd Winter Herring Gull, well, the 1st winter has a more uniformly dark bill, especially at the tip, while the 2nd winter has more of a “ring” similar to the ring billed gull. Other than the bill, 1st and 2nd winter gulls can look relatively similarly.
Candid camera: in the first picture a Ring-Billed is squawking at me.
Photos taken with the Canon Digital Rebel XT / 350D and a Sigma 70-300mm Lens on February 2, 2008 at Leach Park in Bettendorf, Iowa.