At this time of year you may notice Terns offshore being chased by larger birds which resemble young Gulls but are darker brown with pale wing patches, more powerful and more hawk-like in their appearance and actions.
These are Skuas - seabird pirates that chase other seabird (especially Terns), not to catch them but to harry them until they drop the fish they are carrying. Americans call Skuas “Jaegers”, which means “hunters”. This feeding strategy is known as ectoparasiticism.
A Skua harrying a Tern like this is a marvellous display of aerial skill which, in comparison, makes a fighter jet or helicopter look clumsy.
Both birds try to out-manoeuvre the other, twisting and turning often for several minutes. Sometimes the Skua gives up and drifts away with lazy but powerful wingbeats low over the sea. Sometimes it is the Tern that gives up and drops its fish: immediately the Skua, making an incredibly swift somersaulting dive, dramatically catches the fish before it reaches the water.
Skuas do not nest locally - they breed in Orkney and Shetland and further north - but they do pass south along our coast in late summer and autumn on their way to spend the winter off the coast of Africa.
The most usual species is the Arctic Skua followed in order of abundance, by the Great, the Pomarine and the Long-tailed. All have the centre tail feathers projecting beyond the rest. The Arctic Skua (and the rarer Pomarine) come in three colour phases, or ‘morphs’ to use the the ornithological term: all dark, pale (dark above and pale below) or intermediate (dusky all over). Birds of the year are more gingery or rusty brown and more mottled than the adults.
These spectacular avian pirates are well worth looking out for!