Great skua

Appearance

This is a large skua, measuring 50–58 cm long with a 125–140 cm wingspan. One study found that 112 males weighed an average of 1.27 kg and that 125 females weighed an average of 1.41 kg . The adult is streaked greyish brown, with a black cap, while the juvenile is a warmer brown and unstreaked below. Its tail is short and blunt. The flight is direct and powerful. The brown 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 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. Despite its name, the great skua is marginally smaller on average than the other 3 large southern-hemisphere skuas, although not by enough to distinguish them by size in the field. Some authorities still regard the great skua as conspecific with some of these southern skuas, and as a group they have sometimes been separated in the genus ''Catharacta'', although currently this is not commonly followed.

Reproduction

The great skua breeds in Iceland, Norway, the Faroe Islands, and the Scottish islands, with a few on mainland Scotland and in the northwest of Ireland. 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 .

Food

This bird eats mainly fish, birds, eggs, carrion, offal, rodents, rabbits, and occasionally berries.
It will often obtains fish by robbing gulls, terns, and even northern gannets of their catches. It will also directly attack and kill other seabirds, up to the size of great 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. Due to its size, aggressive nature and fierce defence of its nest, the great skua has little to fear from other predators. While fledglings can fall prey to rats, cats or the Arctic fox, healthy adults are threatened only by greater raptors such as the golden eagle, the white-tailed eagle, and more rarely by the orca.