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South Polar Skua | Stercorarius maccormicki
Zuidpooljager | Págalo Polar
The South Polar Skua is the smaller, slimmer relative of the Brown Skua. It breeds on the Antarctic continent and then undertakes one of the longest migrations of any bird, as far as the northern Pacific and Atlantic. In southern Africa it is a scarce but regular passage visitor well offshore.
Voice
Virtually silent at sea. At breeding sites a hoarse, nasal gaa-gaa-gaa and a long call given with raised wings.
Recording: steve — CC BY-SA 4.0 · converted to mono · xeno-canto
Identification
About 53 cm, a bulky, compact skua with broad wings and a short, blunt tail. There are pale and dark morphs with intermediates. Pale birds have a strikingly pale greyish-buff head, neck and underparts that contrast sharply with the uniformly dark, virtually unmarked upperparts and underwing; often a fine pale collar of straw-coloured hackles. Dark birds are uniformly cold brown, lacking the warm tones and rufous blotching of the Brown Skua. The bill is black and proportionately slimmer than in the Brown Skua. All morphs show a white flash at the base of the primaries, above and below. Juveniles are greyer and plainer, with a blue-grey base to the bill.
Confusion species
The Brown Skua (Stercorarius antarcticus) is larger and more heavily built, with a stouter bill and warm brown, blotched and streaked plumage; the South Polar Skua shows either a pale head and body against dark wings or a cold, uniform brown plumage. Dark-morph Pomarine Jaeger (Stercorarius pomarinus) is slimmer, with long, spoon-shaped central tail feathers in adults and barred underwing coverts in juveniles. Young Kelp Gulls (Larus dominicanus) lack the white primary flash and have a paler, barred tail base.
Habitat
Open ocean, especially over the continental shelf and shelf edge. It follows fishing vessels and chases gulls, terns and shearwaters until they drop their prey. Small numbers rest on the water among other seabirds.
Where the bird is most at home, classified by the vegetation units of southern Africa.
Range and movements
In the region a scarce passage visitor off the west coast of South Africa and Namibia and off the south coast, probably often overlooked among the more numerous Brown Skuas; a few reports farther north, off Angola and Mozambique. It breeds along the coast of Antarctica and migrates in the austral winter to the northern Pacific, Atlantic and Indian Oceans.
- Passage (Mar–Apr, Oct–Nov)
- dark = core range, pale = thinly spread
How and when to look
Best on pelagic trips out of Cape Town or Simon's Town, around trawlers on the continental shelf. Look among the Brown Skuas for a smaller bird with a pale head and underparts, or a uniformly cold brown individual without blotching. Good photographs of bill, head and underwing are needed for a record to be accepted.
Conservation status
Not threatened. The world population numbers a few thousand pairs and appears stable. At breeding sites the species is sensitive to disturbance and to changes in the Antarctic food web; at sea, fishing gear and oil pollution pose risks.
Scientific name
Stercorarius maccormicki | Saunders, 1893
Saunders described the species in 1893 and placed it straight away in the genus where it still stands. The genus Stercorarius was introduced in 1760 by Brisson. Stercorarius is Latin for 'of dung', from stercus 'dung': the food disgorged by seabirds when pursued by skuas was once taken for excrement. maccormicki honours the British naval surgeon and naturalist Robert McCormick (1800–1890), who sailed to Antarctica with James Clark Ross. The specimen the first description was based on came from Possession Island, Victoria Land, Antarctica.