Guide to North American Birds

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Photo: Adrian & Jane Binns/Vireo

Great Skua

Stercorarius skua

A big, broad-shouldered, predatory seabird of the North Atlantic. Usually solitary at sea, although concentrations may occur where food is abundant. Breeds mainly in Iceland and on islands north of Great Britain; in North America, very seldom seen from shore, although it may be common far offshore during the winter. Closely related forms are common in the Southern Hemisphere, mostly in subantarctic regions.

Conservation status	Population increasing in northern British Isles, possibly declining in Faeroes, stable in Iceland. Few direct threats to survival other than disturbance at nesting sites.
Family	Skuas and Jaegers
Habitat	Open ocean. Except during breeding season, usually far offshore, out of sight of land. With wide range at sea, occurs over cold and warm waters, from subarctic to equatorial regions. Nests mainly on treeless northern islands with low vegetation, close to colonies of other seabirds.

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Feeding Behavior

Forages in flight by dipping to surface of water, or by picking up items while swimming; scavenges on land, and catches smaller birds in the air. Often harasses other birds, forcing them to drop their food.

Eggs

2, rarely one. Brownish to olive or pale blue, usually with dark brown spots around larger end. Incubation is by both sexes, 26-32 days. Young: May leave nest shortly after hatching, but remain in vicinity. Female stays with young most of time, while male brings back food to feed them by regurgitation. Young capable of flight about 40-50 days after hatching; may become independent soon thereafter, or not for almost 3 weeks.

Young

May leave nest shortly after hatching, but remain in vicinity. Female stays with young most of time, while male brings back food to feed them by regurgitation. Young capable of flight about 40-50 days after hatching; may become independent soon thereafter, or not for almost 3 weeks.

Diet

Mainly fish, birds, carrion. At sea eats mostly fish, particularly species like sand lance which gather in dense schools. Around breeding colonies often preys heavily on smaller seabirds, including kittiwakes and puffins, and eats eggs and chicks of many species. Also eats carrion, insects, and small mammals up to size of rabbits.

Nesting

Usually first breeds at age of 7-8 years. Nests in loose colonies. Pair formation occurs in neutral social areas within or near colony, with much posturing and calling. Nest site is on ground, in open area. Nest (built by both sexes) is shallow depression lined with bits of plant material. In aggressive display near nest, both wings are raised together over back, head extended forward while bird gives harsh calls.

Illustration © David Allen Sibley.
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Text © Kenn Kaufman, adapted from
Lives of North American Birds

Migration

Disperses widely at sea, south to West Africa and Brazil. In North American waters, most common off eastern Canada and New England from October through February. A few non-breeders may be present off North America at any season.