Skua maggiore

Identificazione

Great skuas measure 50–58 cm (20–23 in) long and have a 125–140 cm (49–55 in) wingspan. One study found that 112 males weighed an average of 1.27 kg (2 lb 13 oz) and that 125 females weighed an average of 1.41 kg (3 lb 2 oz). Adults are a streaked greyish brown, with a black cap, while juveniles are a warmer brown and unstreaked below. They have a short, blunt tail, and a powerful flight. The great skua's call is a harsh hah-hah-hah-hah; quacking and croaking noises have also been heard. Distinguishing this skua from the other North Atlantic skuas (parasitic jaeger, pomarine jaeger and long-tailed jaeger) is relatively straightforward. The herring gull size, massive barrel chest and white wing flashes of this bird are distinctive even at a distance. It is sometimes said to give the impression of a common buzzard. Identification of this skua is only complicated when it is necessary to distinguish it from the closely related large southern-hemisphere skuas. Despite its name, the great skua is marginally smaller on average than the other 3 large southern-hemisphere skuas, although not by enough to distinguish them by size in the field. Some authorities still regard the great skua as conspecific with some of these southern skuas, and as a group they have sometimes been separated in the genus Catharacta, although currently this taxonomy is not commonly followed.

Tassonomia

The great skua was described from the Faroe Islands and Iceland by the Danish zoologist Morten Thrane Brünnich in 1764 under the binomial name Catharacta skua. It is now placed in the genus Stercorarius that was introduced by the French zoologist Mathurin Jacques Brisson in 1760. The English name and species name "skua" is believed to originate from the Faroese skúvur or skúgvur [ˈskɪkvʊər] and is the only known bird name to originate from the Faroes that has come into regular use elsewhere. In Britain, it is sometimes known by the name bonxie, a Shetland name of Norse origin. The genus name Stercorarius is Latin and means "of dung"; the food disgorged by other birds when pursued by skuas was once thought to be excrement. The species is monotypic: no subspecies are recognised.

Nome scientifico

Stercorarius skua

Autorità

(Brünnich, 1764)

Ordine

Caradriformi

Famiglia

Stercoraridi

Genere

Stercorarius

Areale e habitat

Areale riproduttivo

PAL : Iceland, Faroe Is., Ireland, Scotland, Norway, Svalbard (n of Norway), and nw Russia to Novaya Zemlya

Areale non riproduttivo

North Atlantic Ocean offshore waters to c Gulf Stream of New England to North Carolina, ne Brazil, North Sea to Iberian Pen., Macaronesia (w of nw Africa), w Africa and w Mediterranean

Migrazione

Complete migrants

Conservazione

Tendenza della popolazione

stable