MA - a new 'white-winged' gull at Turner's Falls

At the risk of sounding like a broken record, there was yet another gull of interest at Turner's Falls two evenings ago. It was an adult, initially quite difficult to pick out from the surrounding Herring Gulls. Overall, it looked pale, slightly frosty but with distinctly white undersides to the primaries and as such, quite the contrast to the surrounding adult Herring Gulls it was resting with. Pale-winged species came to mind and I initially considered it likely an adult Nelson's Gull (American HerringxGlaucous Gull hybrid) but struggled to find any particularly noteworthy hybrid traits. Nor did it look especially like the one adult Nelson's Gull that I saw previously back in 2009 at the Windsor Landfill. It admittedly looked large, bulky and relatively short-winged but I settled on an adult Kumlien's Iceland Gull, perhaps influenced by Eric Huston sighting of an adult Kumlien's from the same site the previous day. Even so, I wasn't especially comfortable with an identification of Kumlien's for no other reason than it just didn't 'feel' right. In haste, I made a decision to post the images on the North American Gulls Facebook page and immediately received responses informing me that bird was clearly not a Kumlien's but much more likely a 'white-winged' Herring Gull or a Nelson's Gull. Peter Adriaens offered a candid, sharp-eyed summary on why it's a Nelson's;

"your bird shows extremely limited black on p6 (restricted to outer web only), which I would consider outside of the variation in smithsonianus. I've certainly never seen this in colonies of argenteus (which generally shows a bit less black on primaries than American Herring). Could well be a hybrid or backcross (with Glaucous Gull).

Some additional shots taken on February 22nd, 2016 at Unity Park, Turner's Falls, Franklin Co., MA.

Here some images of the bird, all taken on February 17th, 2016 at Unity Park, Turner's Falls, Franklin Co., MA.

This last shot is the only other adult Nelson's Gull that I've seen relatively locally. 

It was at the Windsor/Bloomfield Landfill, CT on March 4th, 2009.