© Copyright: Images: Jari Peltomäki, M., W. & F. von Wright: Pohjolan linnut värikuvin. Recording: Jan-Erik Bruun. All rights reserved.
- Name also: Arctic Jaeger, Parasitic Jaeger, Parasitic Skua
- Family: Skuas – Stercorariidae
- Appearance: A long-winged, slender seabird, about the size of a Common Gull. Plumage colouring and patterning vary greatly between individuals. Most birds have a distinct pale patch beneath their wings near the tip. Flight powerful and agile. Often steals food from other seabirds by attacking them in flight persistently until they drop or regurgitate their food.
- Size: Length 37–44 cm, wingspan 100–115 cm, weight 385–600 g.
- Nest: A shallow depression on the ground.
- Breeding: 1–2 eggs laid May–June, incubated by both parents for 24–28 days. Fledglings learn to fly within about 30 days.
- Distribution: Nests on the arctic tundra and remote rocky islands in the outer archipelago. Finnish breeding population estimated at 500–550 pairs.
- Migration: Birds breeding in Finland fly south July–September, returning April–May. Birds breeding in other arctic regions pass through Finland later in the spring and autumn. Arctic Skuas winter around tropical seas in Africa, Asia and the Americas. Birds ringed in Finland have been found as far away as Brazil.
- Diet: Fish, insects, young birds. Steals food from other seabirds, and may also prey on small migrating birds, catching them as they fly over the sea.
- Calls: An elongated mewing “giah”.
The Arctic Skua is slightly smaller and more slender than the similar Pomarine Skua. Individuals have very different plumage, partly depending on their age. There are also two main colour phases: paler birds and more uniformly dark brown birds. Birds of the paler phase have dark brown upper parts and pale underparts. Arctic Skuas have black caps and yellowish cheeks. They often also have an indistinct chest band. Birds of all phases have a pale patch on their primary wing feathers near the wingtip.
Juveniles and dark phase adults are more uniformly dark brown. Adults of the dark phase can be recognised by their elongated central tail feathers, which may be 10 cm longer than their outer tail feathers. These feathers are only slightly elongated on juvenile birds.
Arctic Skuas have dark legs with black-webbed feet. Their bills may be dark brown with blackish tip (mature birds) or bluish grey with a dark tip (juveniles). Their irises are dark brown.