#1. Noble Proctor's and Patrick Lynch's 2005 book, "A Field Guide to North Atlantic Wildlife"
Amazon.com: A Field Guide to North Atlantic Wildlife: Marine Mammals, Seabirds, Fish, and Other Sea Life (9780300106589): Noble S. Proctor, Mr. Patrick J. Lynch: Books
which focuses on the North Atlantic, including the area of our trip.
Directly useful for this trip, especially since it covers whales, seals, rays, fish, turtles, sharks, invertebrates, microorganisms, and seabirds. A highly recommended purchase, at a low cost. Essential reading for every seabirder and naturalist in this marine area. Get it!
#2. Peter Harrison's 1983 book, "Seabirds: an Identification Guide"
Amazon.com: Seabirds: An Identification Guide (9780395602911): Peter Harrison: Books
which covers the whole world, including all the 312 species of "seabirds".
A great classic book, but overkill for this trip, and he has some more recent books on seabirds of the world..
#3. Steven Howell's book which was just published (2012) and will probably become the current Bible for sea birders in North America... "Petrels, Albatrosses & Storm-Petrels of North America"
Amazon.com: Petrels, Albatrosses, and Storm-Petrels of North America: A Photographic Guide (9780691142111): Steve N. G. Howell: Books
complementing another current favorite (2007) book by Derek Onley....
Amazon.com: Albatrosses, Petrels and Shearwaters of the World (Princeton Field Guides) (9780691131320): Derek Onley, Paul Scofield: Books
#4. Blair Nikula's (editor) 2005 book, "Birding Cape Cod"
Amazon.com: Birding Cape Cod (9780975850220): Cape Cod Bird Club, Massachusetts Audubon Society: Books
Probably the best single guide to the best birding locations on the Cape. Only 182 pages, it does not include every location, but it comes close.... thanks to the Dean of Cape Cod birding!
#5. The new "Seabird ID CheatSheet" is now available at this link...
Cape Cod 9/29 seabirds cribsheet (under construction)
including some of the personal ID tips from named contributors.
#6. Relevant websites will be added here....
Here is Keith Mueller's photographic companion site for this 9/29 trip....
New England Coastal Birds: "Provincetown Seabirding Whale Watch"- Searching for the Sabine's Gull (Part 3)