A couple weeks ago I was at the marina on Lake Monroe looking for (and not finding) a Royal Tern that had been seen there earlier. So I occupied my time photographing other terns. I shared photos of Caspian Terns in another post, but there were also Forster's Terns patrolling the marina area. Most of them still had light heads and dark eye patches, but this one has progressed pretty far toward breeding plumage. So I concentrated on this particular individual, with a nearly all black cap and a deeply forked tail (at least on one side).
If you're not familiar with Forster's Terns, here's one in it's basic/winter plumage. As you can see, their looks change a bit this time of year.
By the way, the Royal Tern did show up there a few days later, though it did not cooperate very well for photos. It spent it's time on the seawall east of the marina, too distant (and too cluttered) for good photos. But here's the photo I used to document the sighting on eBird.
Royal Tern (right of center) with Forster's Terns (small ones), Caspian Tern (left)
and Ring-billed Gull