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Black Guillemot Identification

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The Four Keys to ID

  • Size & Shape

    A medium-sized seabird with a heavy body and fairly short, pointed wings. It has a small head and relatively short neck. The bill is straight and sharply pointed.

    Relative Size

    Larger than a Pied-billed Grebe, smaller than a Surf Scoter.

    Relative Sizecrow sizedcrow-sized
    Measurements
    • Both Sexes
      • Length: 11.8-12.6 in (30-32 cm)
      • Weight: 11.3-17.1 oz (320-485 g)
      • Wingspan: 20.5-22.8 in (52-58 cm)

Regional Differences

Ornithologists have described up to 7 subspecies, 2 or 3 of which nest in North America. In Maine and southeastern Canada, arcticus is the nesting subspecies, while in Alaska, mandtii is the nesting subspecies. Some ornithologists also recognize ultimus as a distinct subspecies in the High Arctic of eastern Canada and Greenland; others combine it with mandtii. In adult nonbreeding plumage, mandtii and ultimus have snowy white body plumage; juvenile mandtii/ultimus have white-tipped secondary feathers, forming a white trailing edge to the wing. Some Black Guillemots that nest in western Greenland are mostly black in breeding plumage7, with little or no white on the wings. Such “dark-morph” birds are also much darker in nonbreeding plumage than others in this population, which acquire mostly snow-white plumage in winter.

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