Originally thought to be a 2nd winter Mew Gull - Duxbury Beach, MA - September 10 & 11, 2016... Subsequently, two expert birders concluded that this was an atypical Ring-billed Gull

After the passage of Tropical Storm "Hermine" south of Cape Cod, I found what I thought was a 2nd winter Mew Gull about 2:30 pm (9/10) and re-found 9/11 about 10 am on Duxbury Beach, MA. The location of the “loafing area” where I found it both days is (42.008299, –70.603807).

The bird was hanging out with a group of 5-6 Ring-billed Gulls (RBGU) with a few Herring Gulls and Great Black-backed Gulls in the immediate area.

It’s pretty easy to pick out with a careful look. Somewhat smaller than the RBGUs with the typical differentiating field marks including head shape and bill, but most obvious even from a distance were distinct dark patches above the base of the tail (tertials) on both wings (very clear in some of these photos) which are unique, I believe, to a second year Mew Gull (It turns out that this is not a distinctive mark)_.

Unlike other transients that show up out on Duxbury Beach, this bird doesn’t seem particularly nervous or skittish. A couple of times beach-walkers came close to it. Once it just scuttled out of the away with the RBGUs, and the other time the whole group went up and settled out on the water 50 yards or so offshore. It seemed relatively content; however, my guess is that when the RBGUs decided to move on, it probably moved with them. I could not relocate it on 9/12 9/13 or 9/14 and the groups of RBGUs were also gone. [All this fits with its actually being a RBGU!]