Ring-billed Gull, Larus delawarensis

Breeding adult, with the bright red gape and orbital ring. Ring-billed Gulls do not breed in the San Francisco Bay area; this is presumably a young adult that did not go to the nesting grounds.

Above and left are adult winter, the most common form of this gull seen in the Bay Area.

Second winter -- like adult, but a little brown feathering still on the back, and black feathers showing in the tail.

First winter, left and the two below.

A Juvenile, photographed in Stratford, Ontario -- we don't tend to see Ring-bills in juvenal plumage in the Bay Area. This bird has begun to grow in some adult gray feathers.

FLIGHT PICTURES from here down: The first one is in breeding plumage, with red orbital ring and gape. It's presumably a young adult that stayed where it winters, rather than going to the breeding grounds.

The two above are second-winter, both showing some black in the tail; the one below has an adult all-white tail, but the absence of white spots in the black wingtips shows it to be a second-winter bird.

First-winter birds playing musical chairs on the piers at Palo Alto Baylands, where this species is always present in abundance.

A juvenile -- like the sitting one in the top part of the page, photographed not in the Bay Area, where young winter visitors tend to be molted into first winter plumage,  but in August in Stratford, Ontario.