Sabine's Gulls are not commonly seen from land, so are unfamiliar to most people unless they've spent time on boats offshore. These images are from a pelagic trip to Bodega Canyon and Cordell Bank on 30 August 2013.
Sabine's Gulls are small gulls, with dark gray hoods in breeding plumage. At this time of year, as they transition to nonbreeding plumage, the dark hoods are replaced by paler feathers, as seen in some of the individuals in these photos. Also note the distinctive bill coloration — black with a yellow tip. [Click on the photos to see larger versions.]
In flight, Sabine's Gulls display a dramatic wing pattern — bold triangles of black, white, and gray.
I like this next picture because you can also see the notched tail.
Sabine's Gulls migrate through California from about late July through October. They've nested on arctic and subarctic tundra and will spend the winter in the Southern Hemisphere, primarily off Peru. Wish them luck on their journey south!