Here's an immature Heermann's Gull (Larus heermanni) that I photographed in La Jolla this morning. Another photographer ID'ed it first and when I passed the knowledge on, one lady replied "Oh! That's a lifer for me!" — the Audubon Society's Bird Festival is in town! :D
These two are Royal Terns (Thalasseus maximus) — the bird in focus is in non-breeding plumage, with a white forehead; the bird in the background has the black breeding plumage on the head.
These are a bunch of royal terns (Thalasseus maximus), Forester's terns (Sterna forsteri), and ring billed gulls (Larus delawarensis). The focus is on the Forester's terns closer to the bottom of the frame. This was at Holly Beach, Louisiana.
"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." - allaboutbirds.org
This tern was far away, so the photo doesn't have the detail I would like. It does capture how sleek and streamlined the bird looks in the air.
" large tern, slender and long winged. The head is fairly large and often has a ragged crest at the back. Royal Terns have a substantial body, a long, forked tail, and short legs. The bill is long and daggerlike." - allaboutbirds.org