Best guess is that this is a Gull-billed Tern (Gelochelidon nilotica). The Wikipedia entry for this bird says that the typical black cap on its head disappears in winter and mentions that there is a dark patch through the eye. This sort of fits the bill.
This is pretty much a clean shot. There's a nice "golden hour" glow to the plumage, as I had just arrived early to take sunset photos at the jetty in Venice, Florida.