Lesser Black-backs have been showing up about this time the last few years, though this bird pushes my early date up about a week. Herring Gulls are here in number as well, as well as the 1st young Ring-billed of the season.
This is pretty distant for me, but the yellow legs bright yellow bill and dark back stand out pretty well. This bird has yet to acquire much of its basic plumage head-streaking.