Originally Posted by njlarsen
It can possibly be a least tern, but not a first cy: there is way to much black on the cap. Compare to the one in this thread
No, it is a 1cy Lest Tern. Note how the primaries (and primary coverts) become gradually whiter inwards, which is a certain sign of a 1cy tern. Older terns show a clear moult limit between worn and dark outer primaries and fresher inner primaries. The bird has a white crown, which can be seen if the photo is lightened.