Age: This appears to be a large four-year gull, with pointed primary tips, and with what appear to be 1st generation wing coverts and tertials. It is a rather straight-forward 1st cycle type.
Identification: The overall pallid upperparts here may be due entirely to fading, on what may have been a pale bird to begin with. However, the dark tail, dark primaries and tertials do not appear to have suffered much bleaching or wear. There aren't many four-year gulls in the East that we can confuse this taxon with. Lesser Black-backed is ruled out by virtue of the pale regions throughout the wing panel and the light-gray second generation scaps. The proportions are entirely wrong for Great Black-backed, which also almost never shows an all dark uppertail like this. The most obvious answer is most times the correct answer, and indeed, our May quiz bird is a 1st cycle Herring Gull.
I was surprised by the number of people who replied with "Thayer's Iceland Gull" this month. Although the bill is somewhat slim and the head appears small and refined, this can all be found in a smaller, female type Herring. The paler upperparts are also well within range for a slightly bleached Herring. In fact, there are many 1st cycle Herrings that are much more bleached than this in April (including the flight feathers). Also, Thayer's is generally not expected here and eliminating Herring would be step one.