Great Shearwater

The Great Shearwater is a medium-large shearwater notable for its crisp, well-defined plumage pattern: a dark blackish-brown cap sharply set off from a white collar around the neck, dark grey-brown upperparts often showing a pale, scaly-looking pattern, and white underparts with a distinctive dark smudgy patch on the belly.

This species undertakes one of the more remarkable migrations among shearwaters, breeding almost entirely on a handful of remote islands in the Tristan da Cunha group in the South Atlantic, then migrating across the entire Atlantic Ocean to spend the non-breeding season in the productive waters off eastern North America and Europe.

Great Shearwaters are often seen in large, mixed feeding flocks with other shearwaters, gulls, and marine mammals, drawn to concentrations of small fish near the surface.

Key field marks

• Sharply defined dark cap contrasting with a white collar
• Dark grey-brown upperparts with a scaly pattern, often a pale U on the uppertail coverts
• White underparts with a dark smudge on the belly

Similar species

• Cory's Shearwater has a more uniformly grey-brown head without the sharp cap-and-collar contrast, and a pale bill rather than dark.
• Sooty Shearwater is much darker overall, lacking the white collar and pale underparts of the Great Shearwater.

Great Shearwaters breed almost exclusively on islands of the Tristan da Cunha group and nearby Gough Island in the remote South Atlantic. Nests are dug as burrows in soft soil on grassy or tussock-covered slopes.

After breeding, the species undertakes a long trans-equatorial migration northward across the Atlantic, spending the non-breeding season in productive waters off the eastern coasts of North America and, in smaller numbers, Europe, before returning south to breed.

Voice

Great Shearwaters are largely silent at sea but give harsh, cackling calls at night around breeding burrows during the courtship and nesting period.

Feeding

They feed on fish, squid, and crustaceans, often gathering in large, active flocks alongside other seabirds and marine mammals over schools of small fish, using surface-seizing and shallow diving to catch prey.

Nesting and breeding

Pairs nest in burrows dug into soft soil, visiting the colony mainly at night to avoid predators. A single egg is laid, and both parents share incubation duties before the long return migration north.