Pigeon Guillemot Cepphus columba
Common as winter visitor at off the east region of Hokkaido.
There is a few record of these at off Hokkaido (except the east region of Hokkaido) and the north of Honsyu. They are rarely seen at off the east of Hokkaido in the summer.
Most individuals seen around the Japan are uniformly black (resembling Spectacled Guillemot as winter plumage) and there are few whitish individuals. The individuals seen in Japan have many variations of their coverts (from entirely black to quite white with black line). The whitish individuals considered as subspecies snowi. However I think it is difficult to identify the subspecies by only the color of the body because the whitish individuals ( referred to as subspecies snowi) also have many variations of their coverts.