A tern of the head

A rare tropical seabird has spent weeks charming its way around Scituate Harbor, perching on cars, deck railings, and even the heads of beachgoers and their dogs. Bridled Terns almost never show up in Massachusetts outside of hurricanes, let alone linger all summer acting like a friendly parrot. This week we dig into the sighting history, compare it to a more standoffish bird that's been working…