Great Shearwater Identification

The Four Keys to ID

• Size & Shape

  Great Shearwaters are large shearwaters but are considerably smaller than Herring Gulls. They have long, straight, medium-width wings, and their head and tail project about equally from the body. The bill is thin, and the tail tapers slightly.

  Relative Size

  Larger than a Laughing Gull, smaller than a Herring Gull.

  crow-sized

  Measurements

  • Both Sexes
  • • Length: 16.9-20.1 in (43-51 cm)
    • Weight: 23.6-35.1 oz (670-995 g)
    • Wingspan: 39.4-46.5 in (100-118 cm)

• Color Pattern

  Adult Great Shearwaters have a dark cap and dark brownish-gray upperparts that contrast strongly with a white neck collar and white band at the base of the tail. Seen from below, they are mostly white, with brown smudges on the belly and underwings. The wings have dark edges.

• Behavior

  Great Shearwaters have a stiff flight style, keeping their wings straighter than similar Cory’s Shearwaters. In light winds, they fly low over the water, following short flapping series with longer glides. In stronger winds, they arc higher and sometimes wheel steeply into the wind. Great Shearwaters often occur in large groups at sea. They forage by diving for prey or picking it from the ocean surface. Great Shearwaters are attracted to fishing boats, where they are vocal and aggressive.

• Habitat

  Outside of their breeding season, Great Shearwaters are most common in the cooler waters over the North Atlantic continental shelf. They breed on four small islands in the South Atlantic from September to May.