South Polar Skua
Stercorarius maccormicki
Bulky cold-brown seabird with white wing flashes. Usually seen singly in strong and direct flight, sometimes resting on the ocean with rafts of shearwaters. Chases gulls, large shearwaters, and even boobies, forcing them to regurgitate their food. Plumage overall rather plain, dark gray-brown, suggesting a muscular immature gull but with big white wing flashes, like the smaller, more lightly built jaegers. Often shows a pale blaze across the nape. Some birds have very pale blonde head and body. Breeds in Antarctica, further south than almost any other species of bird. Ranges across all oceans, mainly from March to October, typically staying offshore and very rarely seen from land. Compare with other skua species. In North Atlantic, Great Skua is warmer-toned, has a more capped or hooded appearance, and adults have golden spangles on upperparts. Separation from Brown Skua in Southern Hemisphere is more problematic; there are multiple populations of Brown Skuas and hybrids with South Polar are quite frequent! South Polar averages smaller-billed and slightly less bulky than Brown, and never has bold streaks or spangles on upperparts, but many birds are best left unidentified.
Identification
The south polar skua is a large bird (though small compared to other skuas sometimes placed in Catharacta) that measures around 53 cm (21 in) in length. Adults are greyish brown above, and have a whitish (pale morph) or straw-brown (intermediate morph) head and underparts, and the contrast between head and body makes it easy to separate from similar species with good views. Juveniles and adult dark morphs are harder to distinguish from their relatives, and more subjective or difficult-to-observe criteria, such as the colder brown plumage and blue bill base, must be used.<p>Distinguishing this skua from the Northern Hemisphere Arctic, pomarine, and long-tailed skuas is relatively straightforward. The large size, massive barrel chest, and white wing flashes of this bird are distinctive even at a distance. The flight is direct and powerful. Identification of this skua is more complicated when it is necessary to distinguish it from the closely related great skua of the North Atlantic, and the other large Southern Hemisphere skuas. Identification problems make claims of any Southern Hemisphere skua in the eastern North Atlantic problematic, and few records of south polar skua have been accepted in Western Europe. Similar problems occur, of course, with extralimital claims of great skua.
Taxonomy
- Scientific name
- Stercorarius maccormicki
- Authority
- Saunders, H, 1893
- Order
- Charadriiformes
- Family
- Stercorariidae
- Genus
- Stercorarius
Range and habitat
It breeds on Antarctic coasts, usually laying two eggs in November and December. It is a migrant, wintering at sea in the Pacific, Indian, and Atlantic Oceans. In the eastern North Atlantic, it is replaced by the great skua. South polar skuas have been seen at the actual Geographic South Pole. Megalestris Hill, on Petermann Island in the Wilhelm Archipelago of Antarctica, is named after an obsolete generic name for the south polar skua.
- Breeding range
- AN : coastal Antarctica, especially Ross Sea; also South Shetland and South Orkney is. (off Antarctic Pen.)
- Non-breeding range
- to n offshore waters and North Indian Ocean: mostly clockwise to Japanese and Korean waters (w North Pacific) and Gulf Stream of e USA (w North Atlantic), then sw Canada to n Baja California (nw Mexico; e North Pacific) and nw Africa (e North Atlantic)
- Migration
- Complete migrants
Behavior
Like other skuas, it flies at the head of a human or other intruder approaching its nest.[citation needed]<p>The south polar skua eats mainly fish, often obtained by robbing gulls, terns and even gannets of their catches. It also eats other birds, rabbits, and carrion. Like most other skua species, it continues this piratical behavior throughout the year, showing less agility and more brute force than the smaller skuas (jaegers) when it harasses its victims.
Conservation
- Population trend
- stable
Photos
Distribution
Bird Calls
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