Great Skua
Least ConcernCatharacta skua
Visual Identification
Great Skua
Appearance
The Great Skua is a robust seabird with dark brown plumage, often mottled with lighter streaks. It has a distinctive stocky build, with a large head, powerful hooked bill, and broad wings that give it a gull-like silhouette in flight.
Adults display white wing patches visible during flight, while juveniles are more uniformly dark. There is little seasonal variation in plumage, and sexes are similar in appearance.
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.
Size
Length
50cm to 58cm
Wingspan
125cm to 140cm
Weight
1.2kg to 1.8kg
Colours
Males and females have similar plumage
Primary Colour
Brown
Secondary Colour
White
Beak Colour
Black
Leg Colour
Black
Habitat and Distribution
Habitats
Woodland
Garden
Wetland
Coastal
Urban
Farmland
Grassland
Desert
Tundra
Rainforest
Mountain
Savanna
Distribution
Great Skuas primarily inhabit coastal areas and open seas in the North Atlantic. They breed on coastal moorlands and grassy islands in northern Europe, with significant populations in Iceland, Norway, and the British Isles, particularly Scotland.
During non-breeding seasons, they disperse widely across the North Atlantic, reaching as far as North America and West Africa. In the UK, they are most commonly seen around the northern isles of Scotland.
Elevation Range
Sea level to 100 meters
Climate zones
Subarctic, Temperate
Distribution Map
Distribution by Region
Behaviour and Ecology
Bird Attributes
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Diet
Great Skuas are opportunistic feeders with a varied diet. They primarily consume fish, often stolen from other seabirds, but also hunt small birds, eggs, and chicks.
They often scavenge carrion around fishing vessels or intimidate Gannets and other seabirds into surrendering their prey. They also hunt other seabirds like Kittiwakes and Puffins.
Their adaptable feeding habits allow them to exploit various food sources in their marine environment.
Behaviour
Great Skuas are known for their aggressive behaviour, often chasing and harassing other seabirds to steal their food, a practice called kleptoparasitism. They are strong flyers, capable of swift aerial manoeuvres when pursuing prey or defending their territory. During the breeding season, they become fiercely territorial, dive-bombing intruders who approach their nests.
Vocalisation
The Great Skua's call is a harsh, guttural 'gah-gah-gah' or 'skua-skua', often heard during territorial disputes or when defending nests. During courtship, they produce a softer, mewing call. Their vocalisations are generally loud and distinctive, fitting their bold and aggressive nature.
Nesting & Breeding
Great Skuas form monogamous pairs and breed in loose colonies. The breeding season typically begins in May, with pairs performing elaborate aerial displays during courtship.
Nests are simple scrapes on the ground, often lined with grass or moss. Females usually lay two eggs, olive-brown in colour with dark blotches. Both parents take turns incubating the eggs.
Incubation lasts about 29 days, and chicks fledge after 40-50 days. Parents continue to feed and protect their young for several weeks after they have fledged.
Lifespan
years
The Great Skua typically lives for 20 to 30 years.
Like all birds, lifespan can be affected by factors including predation, habitat quality, disease, and access to food sources.
Conservation and Status
Global Conservation Status
While currently listed as Least Concern, Great Skuas face threats from climate change affecting their breeding habitats and food availability. Overfishing can reduce their prey species, and they are vulnerable to marine pollution, particularly oil spills.
Conservation efforts focus on protecting their breeding sites and maintaining healthy marine ecosystems.
Birdwatching Tips
- Look for Great Skuas near seabird colonies, especially in the North Atlantic.
- Observe their distinctive flight pattern: powerful and direct with deep wing beats.
- Listen for their harsh, gull-like calls, especially when defending territory.
- In the UK, visit Shetland or Orkney Islands during summer for the best chances of spotting them.
Additional Information
Quick Facts
Other names:
Bonxie
Family:
StercorariidaePredators
Adult Great Skuas have few natural predators due to their size and aggressive nature. However, eggs and chicks may fall prey to gulls, ravens, and Arctic foxes in some areas.
Did You Know?
- Great Skuas can live for over 30 years in the wild.
- They are known as 'pirates of the sea' due to their habit of stealing food from other birds.
- Great Skuas are one of the few bird species known to attack humans who approach their nests.
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FAQs
Why is a Great Skua called a Bonxie?
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’, a fitting description for these solidly built seabirds.
References
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website: BirdLife International. 2018. Catharacta skua. The IUCN Red List of Threatened Species 2018: e.T22694160A132532556.
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