Ring-billed Gull - Larus delawarnsis

Once thought to be the most common gull in North America, Audubon called it "the great American gull."  However today for sheer breadth of distribution that appellation is now claimed by the Herring Gull, having become so ubiquitous that it is what most people mean when they mention a 'sea gull',
The black ring around the bill is definitive in identifying this Ring-bill.   He flew right up almost within an arms-length of me, landed on the piling and then gave me a saucy once-over as I laughingly took his photograph.  I was actually more interested in the upstream mergansers but they were wary as always, swimming away even though at a good distance as I was walking toward them - and in fact suddenly taking wing and became gone.