Forster's Tern (Sterna forsteri), Bodega Harbor, 19 January 2013
At this time of year, note the distinctive black mask, sometimes referred to as an eye patch, other times as an ear patch. You can also see the black bill, orange legs, and long tail. (In the breeding season, the entire cap will be black and the bill will become orange with a black tip.)
Recently I've seen up to five Forster's Terns in the harbor. Last Saturday there were two individuals feeding over shallow water and roosting on the tidal flats.
Forster's Terns are very pale above and below. But when you get a close look, you can see that there's some darker gray in the primaries (at the tips of wings) — see next photo.
Forster's Terns don't nest in Bodega Bay (but some nest in the San Francisco Bay area), and most will depart Bodega Bay by the end of April.
According to the Dictionary of American Bird Names, Thomas Nuttall named Forster's Terns after Johann Reinhold Forster, a naturalist who accompanied Captain Cook on his voyage around the world in 1772.