MA - puzzling adult gull at Turner's - 11/17

Looking through the gloom of a wet, dank Sunday afternoon I wasn't really expecting to find much on the power canal at Turner's Falls. The light was beginning to go andI contemplated my options for the final thirty minutes of daylight. I was just about to leave when four female Goldeneyes flew in, one of which was a first-winter female Barrow's - my first of the season.

A small gull flock contained a handful of Great Black-backed and Herring Gulls, but with no Lesser Black-backed or Kumlien's Gulls present I focused on trying to get an image of the Barrow's Goldeneye. When I looked at the gulls again the numbers had swollen slightly. With them came the beauty featured below - but what is it? Before giving a few more details from notes taken at the scene, I want to circulate the images first. Just to be clear, distance and gloom prevented me from establishing two important characters;

1) I could not define the color of the orbital ring with any clarity.

2) Because the bird was swimming during the whole observation, I could not establish the leg color with certainty but from what I saw of the tibia (during preening) the upper legs may have been pale yellowish-green.

Here's a few digiscoped images taken in the fading light;

 

 

unidentified gull (left) - with Great Black-backed (rear) and American Herring Gulls (right).

Turner's Falls power canal, Franklin Co., MA. November 17th, 2013.