叉尾鷗 Xema sabini

Small oceanic gull with stunning wing pattern. All ages show distinctive black outer wing, white inner wing, and dark back. Breeding adults have a dark gray head and black bill with yellow tip. Nonbreeding adults have similar distinctive bill but with a mostly white face. Young birds are browner above than adults, with a crisp scaly pattern on the back. Breeds on Arctic tundra. Often seen in flocks during migration and winter, generally far offshore. Rarely seen from shore, but occasionally shows up at large inland bodies of water.