I'm having a lot of trouble identifying one of the seabirds though. I have zero experience with Shearwaters (or any pelagics for that matter), but Manx Shearwaters are a common sighting off Revere Beach right now so Shearwaters are at the forefront of my mind.
Looking at my guidebooks and pictures online Audubon's Shearwater looks like a close match. *UPDATE: Thanks to Steve from Shooting My Universe for the tip that this is likely a Manx. He lives in Gloucester and I consider him an expert on sea birds. Thanks Steve!
I also could be completely off- these might not be Shearwaters at all. Any ideas?