Flashing slender, silvery wings and an elegantly forked tail, Forster's Terns cruise above the shallow waters of marshes and coastlines looking for fish. These medium-sized white terns are often confused with the similar Common Tern, but Forster’s Terns have a longer tail and, in nonbreeding plumage, a distinctive black eye patch.
Where Common breeds on outer beaches and barrier islands, Forster’s nests farther inland, on edges of freshwater marshes and saltmarshes. It is the only medium-sized tern species found in the United States mainland in winter. Cornell All About Birds
