Brown Skua
The brown skua is a large, heavily built seabird of the Southern Ocean, instantly recognizable by its dark brown plumage, broad wings with white flashes, and thick hooked bill. One of the most dominant birds in its range, it earns part of its food through kleptoparasitism, chasing gulls, petrels, and terns until they drop their catch. It also hunts directly, taking the eggs and chicks of penguins and other colonial seabirds, and scavenges seal carcasses. Breeding pairs, and in some places trios, hold fiercely defended territories on coastal ground on the subantarctic islands, the Antarctic Peninsula, the Falklands, the coast of Patagonia and islands off New Zealand. Each pair typically raises one or two chicks per season. Outside the breeding season, brown skuas roam widely over open ocean, reaching the waters off Uruguay, South Africa and Australia. With an estimated 26,000 to 28,000 mature individuals, it is far less numerous than many seabirds, but the IUCN lists it as Least Concern.
Habitat and distribution
Across the Southern Ocean, brown skuas occupy some of the most remote coastlines on Earth. The Falkland skua, one of its three subspecies, breeds in the Falkland Islands and along the coast of Patagonia in Argentina. The subantarctic skua, the most widespread form, nests on South Georgia, the South Sandwich and South Orkney Islands, the South Shetlands and the Antarctic Peninsula, as well as on subantarctic islands such as Marion, Crozet, Kerguelen, Heard and Macquarie, and on New Zealand's Chatham, Auckland, Campbell and Antipodes Islands. The third, the Tristan skua, lives on Tristan da Cunha and Gough Island in the South Atlantic. On the Antarctic Peninsula, pairs nest close to penguin colonies, which provide a reliable source of food, while deeper into the Antarctic continent the brown skua is replaced by its cousin, the south polar skua. They prefer rocky or grassy coastal ground when nesting. Outside the breeding season, brown skuas become truly pelagic, ranging over the open ocean to the waters off Uruguay, southern Brazil, South Africa and southern Australia, though the heart of their range remains the cold, productive waters of the Southern Ocean.
What does the brown skua eat?
Few seabirds match the brown skua's flexibility as a feeder. Kleptoparasitism is one of its most effective strategies: it pursues gulls, terns, petrels, and other seabirds with relentless aerial chases, forcing them to drop or regurgitate their catch. Brown skuas also hunt directly, raiding penguin and petrel colonies to take eggs and small chicks, and on some islands they catch adult petrels at night as the birds return to their burrows. Fish, squid, and krill are caught at the ocean surface when conditions allow. Carrion, including the carcasses of seals and other marine animals, rounds out the diet, particularly outside the breeding season. Near fishing vessels, brown skuas readily scavenge discarded bycatch and offal. This broad diet is one of the keys to its success in such a vast and variable environment.
Size and appearance
Built for power rather than speed, the brown skua is the largest of all the skuas, with a body length of around 52 to 64 centimeters, a wingspan of 126 to 160 centimeters and a weight of about 1.2 to 2.2 kilograms, heavier than most gulls of the same length. On the Chatham Islands, females average almost 2 kilograms, one of the highest averages recorded for any bird of its group. The plumage is dark brown, often with paler streaks and mottling on the head, neck and back. The bill is heavy and strongly hooked at the tip, well suited to tearing food apart. At the base of the primaries, white wing patches flash visibly in flight and are one of the most reliable field marks of all large skuas. The legs and feet are black. Females are usually larger than males, as in other skuas. Compared with the south polar skua, it is bigger, warmer brown and more mottled, without the polar skua's pale grayish head and body. Compared with the great skua of the North Atlantic, it is very similar, but the two never meet: one lives in the Southern Hemisphere and the other breeds in Iceland, Scotland and Norway.
Brown skua, great skua and other skuas
The name skua covers seven species of seabirds, and many people searching for it are thinking of a different one. Four are large, bulky skuas: the brown skua of the Southern Ocean; the great skua of the North Atlantic, the bird known to birdwatchers in Scotland, Iceland and Norway; the south polar skua, which breeds on the Antarctic continent and crosses the equator every year to spend the southern winter in the North Pacific and North Atlantic; and the Chilean skua, which nests along the coasts of southern Chile and Argentina, with cinnamon underparts and a dark cap. The other three are smaller and more slender, with long central tail feathers, and are called jaegers in North America: the pomarine, the parasitic or arctic skua, and the long tailed skua, all of which breed in the Arctic. The large skuas were long grouped in the genus Catharacta, and BirdLife and the IUCN still use that name, so the brown skua appears there as Catharacta antarctica, while most modern lists place all skuas in Stercorarius, as Stercorarius antarcticus. The great skua, Catharacta skua, is probably a descendant of brown skuas that crossed into the Northern Hemisphere. Where their ranges meet, brown skuas sometimes hybridize with south polar and Chilean skuas.
Behavior
Boldness defines the brown skua more than almost any other trait. Breeding pairs are fiercely territorial, launching direct aerial attacks on intruders that venture too close to the nest, including humans, seals, and even larger birds. Each pair defends a clearly defined territory around its nest site, and these boundaries are maintained with great consistency from one season to the next. Away from the breeding colony, brown skuas are less aggressive but remain dominant birds, able to intimidate most other seabirds. Most breed in monogamous pairs that return to the same territory year after year, but in some places, such as the Chatham Islands and South Georgia, a female may share a territory with two or more males in a lasting trio, an unusual system called cooperative polyandry. Outside the breeding season, individuals tend to be solitary at sea. Vocalizations are used mainly to defend territory and reinforce the bond between a pair, and include loud calls and elaborate displays near the nest.
Conservation
The IUCN classifies the brown skua as Least Concern, but it is not an abundant bird: the global population is estimated at only 26,000 to 28,000 mature individuals, spread thinly across many remote islands. Marion and Prince Edward Islands, for example, hold around 1,000 breeding pairs. There is no evidence of a steep overall decline, and on some islands numbers have grown where fishing discards or seal colonies offer extra food. That said, certain local colonies face real pressures. Human activity at research stations in Antarctica can disturb nesting pairs, and introduced predators on some subantarctic islands have historically threatened ground nesting birds; at the same time, the removal of introduced rabbits and rodents from islands such as Macquarie has changed how much prey the skuas find. Shifts in prey availability linked to ocean warming and fishing pressure are also a long term concern, and outbreaks of avian influenza have killed skuas in the Antarctic region since 2023. The species benefits from protections under the Antarctic Treaty and associated agreements, which limit direct human interference across much of its breeding range.
Where it is found
The Brown Skua can be found in places such as:
