The Black Turnstone (Arenaria melanocephala) is a species of small wading bird. It is one of two species of turnstone in the genus Arenaria, the Ruddy Turnstone (A. interpres) being the other. It is now classified in the sandpiper family Scolopacidae but was formerly sometimes placed in the plover family Charadriidae. It is native to the west coast of North America and breeds only in Alaska.
San Francisco Bay
two turnstones squabbling with each other