Rare in the Pribilofs, Common Mergansers are recorded in roughly one out of every four years. The North American subspecies, Mergus merganser Americana, breeds in south and south-central Alaska and is rare throughout the Bering Sea. The Goosander, or old-world subspecies (Mergus mergaser merganser) has been found to be a rare spring migrant through the western Aleutians and has likely reached the Pribilof Islands. To separate Common from Red-breasted Merganser (regular in the Prib’s) look for the male’s all green rounded head and immaculate white flanks, and the females bright white throat patch and pale gray flanks. To separate the two subspecies from one another it is best to see the birds in flight. The North American birds should show a thin black bar across the white secondaries. This bar is lacking in the old-world form.