Great Shearwater

Identification

The Great Shearwater is a large, powerfully built seabird measuring 43–51 cm in length with an impressive wingspan of 105–122 cm. Its plumage is distinctive and relatively easy to identify: dark upper parts contrast sharply with white underparts, though a diagnostic brown belly patch and dark shoulder markings break up the white below. Look for a black cap, black bill, and a striking white "horseshoe" marking at the base of the tail. The bird's stiff, direct flight style—with wings held straight and few wingbeats, skimming low over the water—is characteristic of shearwaters and helps distinguish it from other seabirds.

Within its range, the Great Shearwater may be confused with Cory's Shearwater or the all-dark Sooty Shearwater, but its size, white underparts, and distinctive markings separate it from these species. The flight pattern, reminiscent of a large Manx Shearwater, is also a useful identification feature for observers watching from ships or coastal vantage points.

Range & Habitat

The Great Shearwater follows a remarkable circular migration route spanning the Atlantic Ocean. It breeds colonially on rocky islands in the South Atlantic, including Nightingale Island, Inaccessible Island, Tristan da Cunha, and Gough Island. After breeding, these birds undertake an extraordinary transhemispheric migration, moving north along the eastern seaboards of South and North America before crossing the Atlantic in August.

During this northward passage, Great Shearwaters can be quite common off the southwestern coasts of Great Britain and Ireland. They then return south along the eastern Atlantic littoral, completing their circular route. This migration pattern is unusual among birds, as most species migrate from north to south rather than from Southern to Northern Hemisphere breeding grounds.

Behaviour & Diet

The Great Shearwater is highly gregarious and exhibits the characteristic "shearing" flight of its genus, dipping from side to side on stiff wings with wingtips nearly touching the water surface. Its flight is powerful and direct, covering vast oceanic distances with remarkable efficiency. These social birds gather in large numbers, often visible from ships or coastal headlands, and produce a distinctive piercing "eeyah" cry when resting in groups on the water.

This species feeds primarily on fish and squid, which it captures from the surface or through plunge-diving. It opportunistically consumes crustaceans, fish entrails, and other discards from fishing vessels, readily following boats and engaging in noisy feeding competitions. Great Shearwaters breed in large colonies, nesting in small burrows or open grass on their island breeding grounds, with breeding birds visiting nests only at night to avoid predation by large gulls. Notably, this species shows among the highest incidence of plastic ingestion among seabirds.

Best Time & Places to See It

August is the optimal month to observe Great Shearwaters, as this is when they cross the Atlantic during their northward migration. The southwestern coasts of Great Britain and Ireland offer excellent opportunities to see these birds in good numbers during this period. Seabird enthusiasts should position themselves on appropriate headlands or take boat trips offshore, where Great Shearwaters can be seen in large, sometimes spectacular gatherings.

The species is most reliably encountered during migration periods from ships or coastal observation points. Its gregarious nature means that when Great Shearwaters are present, multiple individuals are often visible together, creating rewarding viewing opportunities for patient observers.

Photography Tips

Photographing Great Shearwaters requires patience and positioning. Seabird photographers should focus on headlands or take boat trips during the August migration peak when birds are most numerous. The birds' low, skimming flight over water makes them challenging subjects, but their powerful, direct flight pattern offers dynamic photographic opportunities if you anticipate their movement.

Key identifying features to capture include the white "horseshoe" tail marking, the brown belly patch, dark shoulder markings, and the distinctive black cap and bill. Photographing birds while they're resting on the water allows for clearer detail shots showing plumage patterns. Early morning light on coastal headlands often provides the best conditions for capturing these striking seabirds against the Atlantic backdrop.