Hydroprogne caspia
Order Charadriiformes
Family Laridae
Subfamily Sterninae
Adult.— Top of head black; back and wings pearl-gray; tail and under parts white; bill bright red.
When a student has learned readily to distinguish a tern from a gull he may hope to identify the Caspian Tern, which is a rare migrant off the coast in August and September. The black cap, the forked tail, and the red bill mark it as a tern; its size separates it from the other species found on our coast.
Hoffmann – A Guide to the Birds of New England and Eastern New York (1904)