Sooty shearwater

Voice

Entirely silent in the North Sea and off the Spanish coast; this species does not call in Europe. At the southern-hemisphere colonies it is deafening at night: a hoarse, two-part inhaling and exhaling groan, koo-oo-oo-ah, rising from thousands of burrows at once. That sound belongs only to November to April on islands off New Zealand, Chile and the Falklands.

Identification

Large, uniformly dark and very fast. The silhouette is a long narrow cigar with fairly long, pointed, scythe-shaped wings set well back, and a tapering tail. The flight is its signature: a few powerful stiff beats followed by a long glide in which the bird banks steeply over the crests, towering up and diving down again — in a strong wind it shoots through the field of view in high arcs, far quicker and more direct than any gull. From above and at range uniformly dark brown to black. The clinching mark is underneath: an elongated silvery-white panel across the primary coverts that flashes like a mirror as the bird banks, so it alternately looks black and silver. The bill is long, thin and dark.

Confusion species

Yelkouan Shearwater is smaller and more compact, with a dirty white belly and pale axillaries, and is never uniformly dark below. Manx Shearwater is sharply black and white and much smaller. The dark morph of Northern Fulmar is the hardest: it has a thick neck, blunt head, short yellow bill and much stiffer, straighter wings without the silvery underwing panel, and it does not tower so high above the swell. Great Skua is bulkier and broader-winged, with white flashes at the base of the primaries on both wings and a slower, raptor-like beat. Arctic Skua is slimmer with pale underparts and elongated central tail feathers.

Habitat

Wholly pelagic outside the breeding season, over the continental shelf and shelf edges, pursuing small fish, squid and krill by diving; it can reach depths of tens of metres. Breeds in self-dug burrows on grassy and wooded island slopes in the southern Pacific and Atlantic. In European waters purely a visitor, always at sea and never ashore.

Range and movements

Does not breed in Europe. From July to November it moves clockwise through the North Atlantic; the main route runs along the western coasts of Britain and Ireland and across the Bay of Biscay, with a smaller share entering the North Sea. Along the Dutch coast it is a scarce but annual migrant, with tens to a few hundred birds in a good autumn, almost always on north-westerly winds. In Spain it is numerous off Galicia and in the Bay of Biscay, with thousands on peak days in September and October, and scarcer in the Strait of Gibraltar.

• Winter
• Passage
• dark = core range, pale = thinly spread

Where and when to look

Dutch seawatches in a firm north-westerly in September and October offer the best chance; Westkapelle, the Brouwersdam, IJmuiden and Camperduin sit on the flight line. Do not look for colour but for flight style: a dark bird arcing far higher and faster than the gulls around it. Galicia is incomparably better: Estaca de Bares or Cabo Vilán in September on a north-westerly produces hundreds to thousands in a morning, often close under the headland. The ferry to Santander or Bilbao is a good alternative in the same period.

Conservation status

Near Threatened. The world population still runs to many millions, but numbers have been falling for decades. Historical and still-permitted harvest of chicks on New Zealand islands, bycatch in longline and trawl fisheries, and shifts in food supply driven by ocean warming are the main causes. In European waters bycatch is the principal issue; the migration route through the Bay of Biscay overlaps with intensive fishing.