Scientific name: Stercorarius longicaudus Vieillot, 1819
Bird group: Skuas
Field characters. 48-53 cm (tail streamers 13-20 cm). A slender Skua, about the size of a Black-headed Gull. Dark morph extremely rare. Light morph as in light morph Arctic Skua, but never with a breast band. Head with black cap. Throat, breast and upper belly creamy white to yellowish. Lower belly down to undertail coverts dark grey. Light neck separates black head from dark upperparts. Whole upperparts slate-grey, paler than in Arctic and Pomarine Skua. Underwings look black in flight. All flight feathers and tail feathers black. Upperwing coverts have same greyish colour as back and are thus lighter than flight feathers. Unlike other skuas, almost no white in wings. Central tail feathers are very elongated, but may be broken off. Bill black, legs in adult with blue to grey spots, with only the webs completely black. Adult in flight looks more slender than other skuas, due to relatively narrower wings. Juvenile is 'cold' brownish grey, heavily barred; difficult to distinguish from Arctic and Pomarine Skua, but has short and round-tipped central tail feathers (shorter and pointed in Arctic Skua and very short and blunt in Pomarine Skua); colours greyish, 'cold', without warmer rusty tones; whitish fringes on upperparts narrow and of uniform width (more contrasting than Arctic Skua, which has more buff-reddish fringes); breast uniform and paler individuals have white belly (Arctic Skua never has white belly).
Voice. Outside breeding season usually silent. On breeding places it utters calls like 'kreck', 'queek', 'cree-cree-cree', etc.
Distribution. Occurrence in breeding areas varies according to food supply; might be abundant in one year and completely absent in the next. In summer found in northern hemisphere tundra's, but winters in southern oceans.
Habitat. Breeds in Arctic tundra, both inland and coastal. Outside breeding season only found offshore, but can migrate over land.
Food. Often depends on lemmings in breeding season, but also eats other small rodents, fish, invertebrates and berries. Outside breeding season mainly fish, but also offal. Less prone to food-piracy than other skuas.