Uccello delle tempeste di Wilson

Identificazione

Wilson's storm petrel is a small bird, 16–18.5 cm (6.3–7.3 in) in length with a 38–42 cm (15–16.5 in) wingspan. It is slightly larger than the European storm petrel and is essentially dark brown in all plumages, except for the white rump and flanks. The feet extend just beyond the square ended tail in flight. The European storm petrel has a very distinct whitish lining to the underwing and a nearly all dark upperwing. Wilson's storm petrel has a diffuse pale band along the upper wing coverts and lacks the distinctive white underwing lining. The webbing between the toes is yellow with black spots in pre-breeding age individuals.

Tassonomia

Originally described in the genus Procellaria it has been placed under the genus Oceanites. Two or three subspecies are recognized and one population maorianus from New Zealand may be extinct. The nominate population breeds from Cape Horn to the Kerguelen Islands while exasperatus breeds along the Antarctic coast in the South Shetland and other islands. The population from Tierra del Fuego was described as chilensis (=wollastoni, magellanicus) but this is considered a nomen nudum although some authors have reinstated it, noting that it can be distinguished by white mottling on the belly.<p>The name Mother Carey's chicken was used in early literature and often applied to several petrel species while the generic name of stormy petrel referred to the idea that their appearance foretold stormy weather. F. M. Littler and others called it the yellow-webbed storm-petrel.

Nome scientifico

Oceanites oceanicus

Autorità

(Kuhl, 1820)

Ordine

Procellariformi

Famiglia

Oceanitidae

Genere

Oceanites

Areale e habitat

This species breeds on the Antarctic coastlines and nearby islands such as the South Shetland Islands during the summer of the southern hemisphere. It spends the rest of the year at sea, and moves into the northern oceans in the southern hemisphere's winter. It is much more common in the north Atlantic than the Pacific. Wilson's storm petrel is common off eastern North America in the northern summer and the seasonal abundance of this bird in suitable European waters has been revealed through pelagic boat trips, most notably in the area of the Isles of Scilly and Great Britain.<p>It is strictly pelagic outside the breeding season, and this, together with its remote breeding sites, makes Wilson's petrel a difficult bird to see from land. Only in severe storms might this species be pushed into headlands.

Areale riproduttivo

SO : islets in s Chilean fjords and Cape Horn Arch.; many is., coasts and inland sites in Antarctica; Falklands, South Georgia, Crozet, Heard, Kerguelen (sw to se Indian Ocean) and Macquarie is. (far se of Australia)

Areale non riproduttivo

throughout world oceans except tropical and North Pacific

Migrazione

Migratori completi

Comportamento

Comportamento migratorio: Migratori completi.

Conservazione

Tendenza della popolazione: stabile.

Tendenza della popolazione

stabile