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Brown Booby Identification

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The Four Keys to ID

  • Size & Shape

    A large seabird with a fairly long neck, heavy pointed bill, long wings, and a rather long, pointed tail. It has stout, short legs with large webbed feet.

    Relative Size

    Larger than a Caspian Tern, smaller than a Northern Gannet.

    Relative Sizegoose or largergoose-sized or larger

    Measurements
    • Both Sexes
      • Length: 25.2-33.5 in (64-85 cm)
      • Weight: 33.5-60.0 oz (950-1700 g)
      • Wingspan: 52.0-61.0 in (132-155 cm)

    Shape of the Brown Booby© Bill Adams / Macaulay Library

Regional Differences

Ornithologists recognize four subspecies, of which two occur in North America: brewsteri, which nests in western Mexico, and leucogaster, which nests in the Caribbean and tropical Atlantic. These are similar except in the head and neck color of adult males, which is pale gray in brewsteri and dark brown in leucogaster. The other subspecies are plotus of the Pacific and Indian Oceans (the largest of all subspecies) and etesiaca of the Pacific in Central America and Colombia (the smallest).