Birds
Great Skua
Stercorarius skua · also called bonxie
The great skua does not fish much if it can help it. It waits for a gannet or a gull to catch something, then chases the bird down and shakes it in mid-air until it lets go. Walk near its nest and it will do much the same to you, striking your head from behind again and again.
Overview
Stercorarius skua is a heavy, brown, hook-billed seabird of the North Atlantic, most of the world population breeding in Scotland, Iceland, and the Faroe Islands. It is a kleptoparasite and a predator, robbing other seabirds of their catch and killing their eggs, chicks, and adults.
Piracy and predation
It harries gannets, gulls, terns, and auks in flight until they drop their fish, and it patrols seabird colonies to take eggs and to knock down and kill adult puffins and kittiwakes. It also dive-bombs people who come near its ground nest, striking the head from behind.
The bonxie
In Shetland, its stronghold, it is called the bonxie. It is nearly identical to the large skuas of the Southern Ocean, one of which has been seen closer to the South Pole than any other bird.
Status
Least Concern but declining, with a small world population hit hard by avian influenza since 2021 and by falling fish stocks and fewer fishing discards.
Great Skua: common questions
Why does the great skua attack people?
It is defending its nest and chicks, which sit on open ground with no cover. Great skuas nest in loose colonies on moorland, and a pair will treat any large animal that walks into their territory, sheep, dogs, hikers, researchers, as a threat to the young. The defence is a fast, low strike from behind and above, aimed at the head, delivered with the feet or the body rather than the bill, and repeated on every pass until the intruder leaves. It is startling and can knock a person over or draw blood, but it is not an attempt to hurt anyone for its own sake; walking through a skua colony with a stick or an arm raised overhead usually deflects the strikes.
How does a skua steal food from other birds?
By making flying while carrying a fish more trouble than it is worth. A great skua singles out a gannet, gull, or auk returning to a colony with food, chases it, and then grabs it, often by a wingtip or the tail, and drags or shakes it in the air until the harassed bird either vomits up its stomach contents or drops the fish it is carrying. The skua then breaks off and swoops to catch the falling food, frequently before it reaches the sea. This is called kleptoparasitism, and for a powerful, fast, manoeuvrable bird like the great skua it can be a more reliable way to eat than fishing.
Is the great skua a type of gull?
It is a close relative of the gulls, in the same broad group of shorebirds, but skuas are placed in their own family, the Stercorariidae. They look gull-like, being brown or grey-brown, heavy-bodied, and hook-billed, but they are more powerfully built, more predatory, and more piratical than any true gull. There are about seven skua species. In North America the smaller ones are usually called jaegers, from a German word for hunter, while the large ones like the great skua keep the name skua.
Why are great skuas in trouble now?
Several pressures have converged. The species has a small world population concentrated in a few North Atlantic countries, which makes it vulnerable to any one shock. From 2021, highly pathogenic avian influenza tore through North Atlantic seabird colonies, and great skuas, which scavenge dead and dying birds, were among the hardest hit, with some Scottish colonies losing a large share of their adults in a single season. On top of that, the fish stocks skuas depend on have declined, and changes to fishing rules have cut the amount of discarded fish they scavenge, so the birds were already under strain before the disease arrived.