Scopoli's shearwater

Voice

Silent at sea; noisy at the colony after dark. The call is a nasal, wailing two-part aa-oo, rougher and shorter than the three-part call of Cory's Shearwater and often finished with a hiccup. Males call higher and more nasally, females lower and hoarser. Over an occupied colony on Cabrera or Zembra this becomes a continuous crying chorus from April to August that keeps going all night.

Identification

A large, long-winged seabird with a greyish-brown head and back grading into white underparts without a sharp border, so no cap and no collar. The bill is yellow with a dark band before the tip, but slimmer and shallower than in Cory's Shearwater. The decisive feature is on the underwing: a pale wedge runs from the secondaries through the bases of the outer primaries into the wingtip, so the hand looks two-toned from below rather than evenly dark. The dark trailing edge is also narrower. Flight is sailing with long arcs, but a little lighter and with slightly faster beats than in the heavier Atlantic bird.

Confusion species

Cory's Shearwater is bulkier, has a thicker bill and a wholly dark hand from below with no pale wedge; the two overlap around Gibraltar and off Morocco, where many birds are best left unnamed. Great Shearwater has a black cap, white collar, black bill and a dark belly patch. Yelkouan and Balearic Shearwaters are clearly smaller and darker, with fast shallow beats and much shorter glides. Sooty Shearwater is wholly dark with a silvery stripe on the underwing.

Habitat

Outside the breeding season a bird of open water, favouring the shelf edge, seamounts and the fronts where warm and cool water meet. It forages in low shearing flight, picking small fish and squid from the surface and making shallow plunges; it follows sardine and anchovy shoals driven up by tuna and dolphins and gathers in numbers behind trawlers. It breeds in crevices and burrows on rocky islets and steep cliffs, coming ashore only in darkness.

Range and movements

A breeding bird of almost the whole Mediterranean, from the Chafarinas Islands and the Columbretes in the west to Crete and the Dodecanese in the east, with the largest colony on Zembra off Tunisia. After breeding nearly the entire population leaves through the Strait of Gibraltar in October and November for the central and South Atlantic. In north-west Europe it is a real rarity: large shearwaters passing British, Irish or Dutch headlands are seldom identified to species, and the number of accepted records is tiny. To see one, go to the Mediterranean.

• Breeding (summer)
• Passage
• Migration direction
• dark = core range, pale = thinly spread

Where and when to look

The easiest option in Europe is an evening boat trip off Cabrera, the Columbretes or the Menorcan coast in June or July: birds then gather in rafts of tens to hundreds on the water before going in to the colony after dark, and at that range the pale wedge in the wingtip is easy to check. From land the Strait of Gibraltar works best in October, with an offshore wind and a view over deep water from Punta Carnero.

Conservation status

Not globally threatened (IUCN: Least Concern), but the Mediterranean population is getting smaller. The main causes are bycatch on longlines and in gillnets, rats and feral cats in the colonies, and disturbance by recreation on the breeding islands. Because the birds mature late and lay a single egg a year, adult mortality weighs heavily; clearing rats from breeding islands and modifying longline gear have already produced results in several places.