Stercorarius skua
The Great Skua is a large and intimidating seabird with a reputation for terrorising other marine birds. They nest in Scotland and elsewhere in northern Europe but disperse widely in the Atlantic and Mediterranean each winter.
Great Skua
Great Skua chick
Great Skua in-flight
Great Skua portrait
The Great Skua is a large, stocky, gull-like seabird with dark plumage and a black bill and legs. They appear almost black at a distance, but a closer view reveals dark brown plumage with black, white and yellowish streaks. Flying birds show distinct white wing bars at the base of the primaries.
Females and males look alike, but juveniles are darker than adults and have more uniform plumage without obvious streaking.
Great Skuas could be confused with other Skua species, although they are the largest and heaviest species likely to be encountered in the Northern Hemisphere. They also resemble the dark juvenile plumage of Larus gulls like Glaucous, Lesser black-backed, and Herring Gulls.
Great Skua standing in its natural habitat
Great Skuas are large but stocky and compact seabirds with a total length of 53 to 58 centimetres or about 21 to 23 inches.
Their body weight varies between approximately 1.1 and 2 kilograms or two and a half to four and a half pounds.
Great Skuas are powerful in flight, with wingspans of 125 to 140 centimetres or 49 to 55 inches. This is fairly short relative to similar-sized gulls.
Great Skua standing in a meadow getting ready to take-off
Great Skuas make a variety of harsh, gull-like calls, including a barking ‘Uk-uk-uk.’ They also produce low-pitched croaking calls and cries when attacking intruders at the nest. They are generally silent out at sea in the non-breeding season.
Great Skua calling to warn off an intruder
Great Skuas are fierce predators, aggressive thieves, and opportunistic scavengers. They can catch their own fish, although they often scavenge around fishing vessels or intimidate Gannets and other seabirds into surrendering their prey. They also hunt other seabirds like Kittiwakes and Puffins.
The Great Skua diet includes:
Great Skua chicks are fed by regurgitation. Fish and the flesh and organs of other seabirds and their eggs are the most important components of their diet.
Great Skua in-flight hunting
Great Skuas are pelagic seabirds that spend the winter over offshore waters or nearer the coast along the continental shelf. They come to shore to nest in spring on treeless coastal islands and open moorlands.
Great Skuas are restricted mainly to the Atlantic Ocean, north of the equator. They may be seen off the coasts of Svalbard, Northern Europe, the United Kingdom, Iceland, Greenland, Canada, the United States, and North Africa.
Great Skuas live in marine environments of the North Atlantic Ocean, often far from the nearest land, although they must come to shore each spring to breed. These faithful migrants return to the same place to nest each year and visit the same regions each winter. They are comfortable in the air, on water, and on land.
Great Skuas are scarce birds with a world population of just 30,000 to 34,999 individuals. Their entire population breeds in Europe, where they may be locally common in the nesting season.
Great Skua can be seen in late spring and summer around their breeding grounds on the Shetland and Orkney Islands and around the northern and western coasts of Scotland. They may be seen almost anywhere off the coast of the UK during their spring and autumn migrations, although they are rare in winter.
The best place to see Great Skuas in Canada is around the Grand Banks off Newfoundland, particularly in winter when non-breeding birds migrate from Iceland.
Great Skuas can be seen offshore of the United States’ northeast coast in winter. They may be seen as far south as North Carolina, although sightings are more likely off the coasts of Maine and Massachusetts in New England.
Great Skua resting on the edge of the cliff
Great Skuas are long-lived birds with a maximum recorded lifespan of 38 years and an average life expectancy of about 15 years.
Adult Great Skuas are apex predators among seabirds with few natural enemies. Large birds of prey, like the Golden Eagle and White-tailed Eagle, are potential predators at nest sites.
Great Skuas in the United Kingdom are protected by the Wildlife and Countryside Act 1981.
Great Skuas are not endangered, although they do have an amber conservation status in the United Kingdom. These seabirds are listed as ‘Least Concern’ on the IUCN Red List and are believed to have a stable population trend.
Pair of Great Skuas displaying
Great Skuas nest on coastal moorland and islands where human disturbance is low. They nest in groups, ranging from a few scattered pairs to loose colonies of several thousand. The nest is a grass-lined scrape on the ground on flat terrain with low vegetation cover.
Most of the population breeds in the following areas:
Great Skuas nest from early May to late June. These long-lived seabirds first breed when they are seven or eight years old.
Great Skuas lay two olive-coloured eggs with darker spots. Their eggs are large, measuring approximately 70 millimetres long and 50 millimetres wide.
Great Skuas are thought to mate for life. These territorial birds return year after year to nest within about a kilometre of where they hatched.
Nest of a Great Skua with two eggs
Great Skuas are highly aggressive toward other birds, earning them the nickname ‘pirate of the seas’. They will intimidate other birds into giving up their food or kill and eat other seabirds small enough to overpower. These birds are quite fearless when defending their nests and will not hesitate to divebomb intruders, including humans.
Great Skua acting aggressively
Adult Great Skuas migrate between spring and summer breeding grounds in northern Europe and overwintering grounds as far afield as North America. Individuals that nest in the United Kingdom generally migrate south to the Mediterranean and off the shore of Northwest Africa, while Icelandic breeders head west to overwinter off Canada and the Northeast of the United States.
Great Skuas migrate between ideal nesting grounds in the summer and rich feeding grounds in the winter. Their breeding territory in northern Europe provides safe nesting sites and an abundance of other nesting seabirds to feed their chicks. Each of their various overwintering areas in the Atlantic and Mediterranean offers healthy prey fish populations and numerous fishing boats to scavenge from.
Great Skua in-flight over the blue sea
Great Skuas are traditionally known as Bonxies in Scotland, although the derivation of this quaint Norse word is unclear. Some sources suggest it may mean ‘dumpy’, which is a fitting description for these solidly-built seabirds.
The Arctic Skua (Stercorarius parasiticus) and Great Skua (S. skua) are the two most common Skua species off the UK coast, although they are easily separated by size. The elegant and agile Arctic Skuas (also known as Parasitic Jaegers) are much smaller birds with long, pointed wings and tails.
Scientific name:
Stercorarius skua
Other names:
Bonxie
Family:
SkuasConservation status:
Amber
Length:
53cm to 58cm
Wingspan:
125cm to 140cm
Weight:
1.1kg to 2kg
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