Sky pirates!
With their aggressive behaviour, piratical feeding habits and taste for their neighbours, the skuas may well be Britain’s rudest birds
Why skuas may well be the country’s rudest birds!
Now, no one likes bad behaviour, but you’ve got to admit it’s fun to watch. If you hear two people arguing in a supermarket, you know you’re going to sneak a look; hear a fight breaking out outside the pub, you’ll see everyone running for the nearest window. And when you watch a wildlife documentary with a shot of grazing deer or antelope, you know you’re secretly waiting for the predator to turn up.
In the kingdom of birds, there is one family that is perhaps the worst behaved and thus among the most entertaining to watch: welcome to the world of skuas.
This family of seabirds were also known as the ‘robber gulls’, a name which comes from their way of gathering food. Basically, they steal it. Skuas will chase down gulls, Gannets, terns and just about anything else carrying food, then harass and harry the birds until they drop their catch, before taking it and eating it themselves.
This behaviour is known as ‘kleptoparasitism’. It’s fairly common in the animal kingdom, but it’s actually quite uncommon in birds, at least as a primary food source. Certainly, crows, gulls and birds of prey will steal opportunistically, but none of them rely on it as their main way of obtaining a meal. The skuas and the frigatebirds (large tropical seabirds) seem to be the only two families that are pre-dominantly kleptoparasites. Skuas will mix it up from time to time, although their other ways of gaining food are even less likely to endear them to their neighbours: if a skua sees half a chance it will take eggs and even chicks off unguarded nests, and has even been known to predate smaller adult seabirds, including Puffins.
Basically, if you’re a non-skua seabird, skuas are your worst nightmare.
I mean, imagine you’re a Gannet and you’ve just performed one of the bird world’s great hunting feats – divebombing into the water at 60mph, swimming down to depths of 30m to catch a fish – and then when you’re flying your hard-won prey back to your nest,
a skua chases you until you drop it, then takes it for itself.
Annoying for the Gannet, though thrilling for the birdwatcher. Skuas are spectacular on the wing. Watching them chase down terns, small gulls or even Gannets is the birdwatching equivalent of a World War II dogfight, or the kind of acrobatic aerial battle that seems to occur with perfect regularity towards the end of every Star Wars movie.
Unfortunately, this fast-paced flight, along with the very subtle differences between some members of the family, makes the skuas quite hard to identify, especially if only seen on the move.
Skuas in the UK
There are seven species of skua worldwide, but only four are seen in the northern hemisphere, with the others living around the southern tip of South America or around Antarctica. All four of the northern hemisphere varieties can be seen from the UK, with two species nesting regularly.
The most common is the Great Skua, a large brown bird that looks a little bit like a juvenile Herring Gull, only perhaps a little darker. About 10,000 pairs nest in the UK each year, mostly in the Western
Isles, Orkney and Shetland. Because of their feeding habits, they’re most likely to be found wherever there are large colonies of gulls, and your first indication that they’re around may well be from other birds’ alarm calls or defensive flight patterns.
You get the feeling that Great Skuas are desperate to burst out of their ‘category’ and become birds of prey. As if their aggression and ferocity were not enough, each toe on their webbed feet is tipped with a vicious-looking claw, its beak is hooked downwards like a bird of prey, and the brown plumage looks more like a buzzard than any other seabird.
The second most common skua, and only other breeding species, is the Arctic Skua. It’s smaller than the Great Skua, and can be much lighter in colour, with a whitish breast and a dark black cap. Its distinguishing feature from the Great Skua is its long-tipped tail, though all the other three types have tails of this kind. About 2,000 pairs of Arctic Skuas nest in the UK, so if you’re in the right place (Highlands and islands) in breeding season, you’ve got a decent chance of seeing them, though identifying them against the rarer varieties can be a
Long-tailed and Pomarine
The two species that do not breed in the UK, but that can still occasionally be seen on passage, are the Long-tailed Skua and the Pomarine Skua.
As far as appearances go, the Longtailed Skua is the most impressive. It has a white/yellow underside and a dark black cap, not unlike the Arctic Skua, but its most impressive feature is the long forked central tail streamers which are at least the length of the body.
Unfortunately, it’s a pretty scarce visitor. If you want to add this to your list,
you’ll want to be in the far north of Scotland in May or September and will need more than a little luck.
The Pomarine Skua is seen in spring and autumn on the south and east coast of the UK. It’s a little like a chunky Arctic or Long-tailed Skua, but has a distinct dark band around its chest and instead of a forked or streaming tail, the Pomarine Skua has a tail that is almost spoon shaped, with a round tip.
The name could be a little misleading. Pomerania is the region that straddles the border between Germany and Poland (it’s where the fluffy breed of dog comes from), but neither place nor dog have anything to do with ‘pomarine’. Nor, indeed, does the element ‘marine’ relate to anything remotely maritime.
Pomarine actually comes from the Latin meaning something like ‘lid’ or ‘nostrils’, and refers to the cere, a waxy feature that some birds have that link the top of the beak to the face (think of the beak of a Peregrine, for example, which is mostly dark, but is yellow around where the beak meets the bird’s face – the yellow bit is the cere). The curious thing is that the cere on the Pomarine Skua isn’t especially pronounced, unless you’re seeing the bird at extremely close range.
Sometimes it’s a slightly lighter creamy colour, and sometimes it blends in entirely. It would have been much more helpful had they named it after a feature that was a little easier to spot (Spoon-tailed Skua, anyone? Banded Skua, perhaps?).
At the very best of times, separating Arctic Skua from Pomarine Skua is a challenge, especially since the birds are most often seen far out at sea, usually flying at breakneck speeds in pursuit of some poor other seabird.
Even if you do see one, you might struggle to find what to call it. Skuas, it seems, are birds of many names. In North America, they’re known as jaegers ( particularly the three smaller species), which comes from the German word for hunter. In Shetland, the Great Skua is known as the Bonxie, a name that is said to derive from the Old Norse word bunki, which means something like dumpy, and refers to the bird’s sturdy build. The name has, in recent years, gained more widespread use in the UK.
Pomarine Skuas may also be called pomatorhine skuas, and I’ve even got one antique bird book that refers to it as the ‘twist-tailed skua’ though I can’t find that anywhere else.
The same book refers to the Arctic Skua as Richardson’s Skua, and I know that this bird is also very commonly referred to as the parasitic skua or parasitic jaeger, despite the fact that all skuas are parasitic.
Not wanting to be left out of the identity crisis, I’ve seen the Long-tailed Skua also called Buffon’s Skua. See what I mean about birds of many names?
Despite the variety of names and features, one thing that all skuas have in common is long-distance migration. All of these birds cover some serious ground, or I suppose that should actually be, cover some serious sea.
Great and Pomarine Skuas winter in southern Europe or along the west coast of Africa, while the few Long-tailed Skuas that make it to the UK are known to have travelled from Brazil and Argentina.
There’s a little more mystery around the Arctic Skua, which like most skuas spends much of its life at sea and so is difficult to track.
To address problems in the data and to determine the causes of a rather worrying population decline, the BTO is currently running a project to track the migrations of Arctic Skuas (details on their website, bto.org).
Swirling and fighting
I can’t wait for the return of the breeding seabirds this year. After a fairly long and stationary winter, I’m looking forward immensely to standing on some rugged patch of coastline looking out over hundreds of swirling, calling, fighting birds. If you make it up to the Highlands this year, keep your eyes open for the aggressive, bullying and combative skuas. You may not approve of their behaviour, but you’ll have to admit, they’re pretty fun to watch!
AT THE VERY BEST OF TIMES, SEPARATING ARCTIC SKUA FROM POMARINE SKUA IS A CHALLENGE