Iceland gulls breed in the North Atlantic (Greenland and northeastern Arctic Canada), and some visit more southerly parts of North America, especially in winter.   They rarely make it to the west coast and this very white bird -- a second-cycle immature -- is the first recorded in Riverside County, California (and one of very few from all of southern California).   It was roosting with numerous ring-billed, herring, and California gulls in a dairy pond near the small town of Lakeview, and stayed far away (hence these not-so-good images are highly cropped).   Young gulls are notoriously variable and hard to identify (for me, at least), but this bird shows the short pinkish legs, long wings with white primaries, small bill and round head characteristic of Iceland gulls.   Several experts also agreed on that ID.
          Getting good shots of this gull was mostly a matter of luck (being in the right place at the right time), and several other birders had better luck than I did.

• Canon 1D4; 800 mm IS lens plus 2X converter (2013)