Great Shearwater

Overview

The Great Shearwater is a robust, wide-ranging seabird recognized by its dark cap contrasting with a pale hindneck collar, along with a scaly-looking pattern across the upperparts created by pale-fringed feathers. A dark smudge on the belly is another useful field mark.

It breeds on a small number of remote South Atlantic islands but disperses across enormous stretches of the Atlantic Ocean outside the breeding season, making it a familiar sight to observers on both sides of the ocean.

Great Shearwater feathers show more visible patterning than many other shearwaters.

• Head and neck: Dark brown cap feathers contrast with a paler, whitish hindneck collar, a key distinguishing pattern.
• Upperparts: Feathers have pale fringes creating a scaly or scalloped look across the back and upperwing coverts, distinct from the more uniform tones of Sooty or Cory's Shearwater feathers.
• Underparts: Mostly white, with a dark, smudgy patch of feathers on the belly area.
• Compared to Cory's Shearwater: Great Shearwater has a more clearly defined dark cap and pale collar, while Cory's shows a more uniformly brownish head without strong contrast.

Adults show a blackish-brown cap sharply set off from a whitish collar around the hindneck, scaly-patterned brown upperparts from pale feather fringes, and white underparts marked with a dark belly patch. Sexes look alike. Juveniles resemble adults closely. The complete molt occurs largely away from the breeding season, timed with the bird's extensive transatlantic movements.

Great Shearwaters breed on a handful of remote South Atlantic islands, then range widely across the entire Atlantic Ocean outside the breeding season, reaching well into the North Atlantic during the boreal summer. They are highly pelagic and favor productive offshore waters, rarely approaching land except at their limited breeding sites.

This shearwater feeds on small fish and squid using pursuit-diving and surface-seizing techniques, often gathering in large mixed-species feeding flocks over abundant prey and readily following fishing vessels. Flight consists of stiff-winged glides interspersed with steady wingbeats, well suited to long-distance travel across the Atlantic. Nesting occurs in burrows on remote islands, with a single egg laid per season. Calls are harsh, cackling notes given mainly at nesting colonies after dark.