The Great Skua (Stercorarius skua), is a large seabird. In Britain, it is sometimes known by the name Bonxie, a Shetland name of unknown origin.
This is a large skua 50–58cm in length with a 125–140cm wingspan. Adults are streaked greyish brown, with a black cap, juveniles are a warmer brown and unstreaked below. Their tail is short and blunt. The flight is direct and powerful. This Skua's call is a harsh hah-hah-hah-hah; quacking and croaking noises have also been heard. Distinguishing this skua from the other North Atlantic skuas (Arctic Skua, Pomarine Skuaand Long-tailed Skua) is relatively straightforward. The Herring Gull size, massive barrel chest and white wing flashes of this bird are distinctive even at a distance. It is sometimes said to give the impression of a Common Buzzard. Identification of this skua is only complicated when it is necessary to distinguish it from the closely related large southern-hemisphere skuas. Some authorities still regard the
The Great Skua breeds in Iceland, Norway, the Faroe Islands and the Scottish islands, with a few on mainland Scotland. It breeds on coastal moorland and rocky islands, usually laying two spotted olive-brown eggs in grass-lined nests. Like other skuas, it will fly at the head of a human or other intruder approaching its nest. Although it cannot inflict serious damage, such an experience with a bird of this size is frightening. It is a migrant, wintering at sea in the Atlantic Ocean and regularly reaching North American waters. Vagrant to Mediterranean countries.
This bird eats mainly fish, which it often obtains by robbing gulls, terns and even Northern Gannets of their catches. It will also directly attack and kill other seabirds, up to the size ofGreat Black-backed Gulls. Like most other skua species, it continues this piratical behaviour throughout the year, showing less agility and more brute force than the smaller skuas when it harasses its victims. A common technique is to fly up to a gannet in mid-air and grab it by the wing, so that it stalls and falls into the sea, where the Great Skua then physically attacks it until it surrenders its catch. It also eats small mammals, eggs, berries and carrion. Due to its size, aggressive nature and fierce defence of its nest, the Great Skua has hardly anything to fear from other predators. While fledglings can fall prey to rats, cats or the Arctic Fox, healthy adults are only threatened by the Golden Eagle and the White-tailed Eagle.