South Polar Skua
South Polar Skua
Stercorarius maccormicki
At a Glance
The South Polar Skua occurs regularly off both our coasts, but this predatory seabird nests only far to the south of us, around the edges of the Antarctic continent. When it reaches North American waters, it remains far offshore, pirating food from other seabirds or catching its own fish.
All bird guide text and rangemaps adapted from Lives of North American Birds by Kenn Kaufman© 1996, used by permission of Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Category
Gull-like Birds
IUCN Status
Least Concern
Habitat
Open Ocean
Region
California, Mid Atlantic, New England, Northwest, Southeast, Western Canada
Behavior
Direct Flight, Swimming
Population
11.000
Range & Identification
Migration & Range Maps
From Antarctic nesting grounds, moves far to the north in both Atlantic and Pacific. Perhaps most common off southern California in late spring, off northern California in early fall, and off New England in early summer, but details still poorly known.
Description
Sexes similar — Length: 20–23 in (51–58 cm); wingspan: 4 ft 4 in–4 ft 10 in (1.3–1.5 m); weight: 2 lb–3 lb 8 oz (900 g–1.6 kg). The South Polar Skua is bulky, powerful, with wide wings and a thick neck. Brown with white wing flash (more obvious than in jaegers). Dark back contrasts with pale nape; head and underparts are often paler also. Compare to the Great Skua. Young Pomarine Jaeger can also resemble a skua.
Size
About the size of a Mallard or Herring Gull
Color
Black, Brown, Gray, Tan, White
Wing Shape
Broad, Tapered
Tail Shape
Short, Wedge-shaped
Songs and Calls
Usually silent in American waters.
Call Type
Chatter
Habitat
Open ocean. Ranges widely at sea, over both warm and very cold waters. Appears far off North American coast where there are concentrations of other birds from which to steal food. Almost never seen from shore on this continent. Nests in Antarctica, on islands and mainland, on barren ground.
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Behavior
Eggs
Two, sometimes one. Olive to brown, blotched with darker brown. Incubation is by both sexes, but female does more. Incubation period 24-34 days, usually 28-29.
Young
Both parents feed young, by regurgitation. Young may leave nest soon after hatching, wander in immediate vicinity. Although both eggs usually hatch, usually only one young survives to fledging. Age at first flight 49-59 days.
Feeding Behavior
The South Polar Skua forages at sea by plunging into water from flight, or by seizing items while sitting on the surface. Often steals food from other seabirds: may grab a shearwater or gull with its bill and shake the other bird violently to make it disgorge its catch.
Diet
Mainly fish. Diet in North American waters not well known, but feeds mostly on fish while at sea. On breeding grounds, some feed mainly on the eggs and young of penguins, and on carrion around penguin colonies.
Nesting
In Antarctica, some South Polar Skuas nest close to penguin colonies, feeding on eggs and chicks. Where this species overlaps with the larger Brown Skua, the Brown Skuas effectively "control" the penguin colonies, and the South Polars must forage at sea. Courtship involves much posturing and calling; the male feeds the female. Usually first breeds at 5-6 years; birds usually mate with the same partners and nest in the same sites every year thereafter. In an aggressive display near the nest, both wings are raised together over the back, the head extended forward, while the bird gives harsh calls. The nest site is on the ground. Nest is a simple scrape in soil or moss; often begun by the male and completed by the female.
Conservation
Conservation Status
Numbers apparently stable. Except near a few Antarctic research stations, the haunts of South Polar Skua are usually remote from the impacts of human activities.
