Im working out the terns myself , some of the plumages seem VERY dubious to me , but , Im thinking this is a younger forsters tern. They can have a carpal bar too but paler. the dark wedge in the primaries on this bird , doesnt extend clearly into the coverts , The bill trends to orange more so than red , and the rump is rather clearly defined as white , rather than the gray on common. yes the breast looks dark but Im thinking its brownish soil, If Im mistaken.. Id like to hear your rebuttal. ( Ive yet to identify a common down here in fla yet and want to be able to discern a difference if I do)
Oh, Very nice pic too