British Wildlife of the Week

Capercaillie

A male capercaillie displaying
Image Source: David Palmer

If you happen to be in the ancient Caledonian pinewoods of the Scottish Highlands during April or May, you may hear a very unusual sound. It is often likened to a champagne cork popping and the liquid being poured, but in reverse – starting with the liquid gurgle and ending with the ‘pop’ (listen to it here). These bizarre noises are the spring display calls of the male capercaillie, one of our most impressive and dramatic birds. The male ‘caper’ is certainly very handsome indeed, with glossy, dark grey plumage, reddish-brown wings, and a long tail that is held upright and fanned out during displays.

In the breeding season, several cocks will gather in the same prearranged place, often a forest clearing, to establish dominance. An aggregation of males engaging in competitive displays such as this is known as ‘lekking’, and we discussed this in more detail in the last British Wildlife of the Week post. Each male occupies his own small arena in the courting ground, and it is from there that he displays: strutting, fanning his tail, stretching his neck upwards, and issuing a steady stream of strange guttural calls. In fact, the name ‘capercaillie’ is derived from the Scottish Gaelic capull coille, which means ‘horse of the woods’, a reference to the cantering sound that is the start of this bird’s mating performance.

A male, or cock, capercaillie displaying in the snow, with his tail fanned out
The capercaillie is the largest grouse in the world, weighing up to 5 kg. With his tail fanned in display, the male looks a bit like a turkey crossed with a peacock.
Image Source: Stelvioparc

The best arenas are vigorously contested over, and the largest and strongest cocks in the area invariably gain control of these patches. The males tolerate one another’s presence so long as they remain within their own small territories. However, if arenas overlap, or if a subordinate cock tries to claim a more central territory from a dominant one, physical fights can break out. Birds may be seriously injured or even killed during these violent tussles, but they take this risk because the reward can be very great.

Three-quarters of the caper breeding season consists simply of territorial competition between males on the courting ground as they all attempt to intimidate one another. Only towards the end do the hens actually arrive and select their preferred male. The females greatly benefit from having all the males perform in a confined space because they can compare potential mates quickly and without having to travel far. Soon they will have all made their choice – almost always the strongest and most powerful male who has set up camp in the very middle of the lek – and they flock to his arena to be mated with.

Capercaillie mating is brief. It is also the last point of contact a male bird will have with a particular female. The hen will lay her clutch nearby and be solely responsible for incubating the eggs and raising the chicks. Her brown and russet plumage acts as camouflage and makes her less noticeable to predators, especially when she is sat on the nest.

There are very few winners in this contest, and many losers. Most males on the periphery are universally rejected and will not get a chance to mate during this particular breeding season. Though they have a slim chance of intercepting a female as she moves through the various arenas, males are unlikely to be successful until they win a favoured spot towards the centre of the lek – and that may take several seasons. Until that time, the sexually charged losers become so crazed with lust that, occasionally, they display at and try to chase off anything that comes too close to them, including horses, cars, and even natural history film crews.

A female capercaillie
The female capercaillie is only half the size of the male and lacks his flamboyant plumage. Outside of the breeding season, both sexes are shy, secretive and seldom seen.
Image Source: Honza Sterba

The capercaillie was once found across much of the British Isles, prospering mainly in ancient, old-growth conifer forests. However, gradual but inexorable human expansion and the subsequent loss of their woodland habitat had driven them back to the Scottish Highlands by the end of the 17th century. By 1785, overhunting and huge forest clearances had wiped it out even there, rendering the capercaillie extinct as a British bird. According to one story, the last known caper in the UK was recorded as little more than a novelty dish served to impress guests in Inverness-shire.

Over the following century, various landowners made several concerted efforts to restore the capercaillie to our nation. An attempt to reintroduce the bird (in the estate of Sir Fowell Buxton of Norfolk) in the 1820s ended in failure, but Buxton wasn’t about to give up. In 1837, he tried again, this time on an estate in east Scotland. Several capercaillies were captured in Sweden and relocated to Scotland, causing quite a stir among the locals. A quarter of a century later, capercaillies had been released on several other Scottish estates and their population was estimated at around 2,000 individuals. Of course, they weren’t reintroduced to restore the damaged ecosystem – it was mainly to provide excitement, food, and a prestigious new attraction for visiting shooting parties and Scottish aristocrats.

Although capercaillie swiftly spread and recolonised much of their former range, they began to decline again after the First World War. This has been attributed chiefly to a loss of forest cover, due at least in part to felling during the world wars; thousands of hectares of UK forest were cut down to supply pit props for mines producing coal for the armaments industry. But it was also because, after having become so numerous that they were deemed a menace to forestry, gamekeepers began stamping on capercaillie eggs in spring to keep numbers down.

Even so, capercaillies survived quite well until the 1960s and 70s, when their population numbered as many as 20,000 individuals. Towards the end of the 20th century, however, caper numbers began to fall more rapidly. Today, there are said to be only around 1,000 capercaillies left in Scotland, but this is an old figure; in reality, there are probably considerably fewer. Of course, it’s little wonder they have become so severely endangered: they require vast areas of old, established, well-connected forests, and, as the pinewoods become increasingly fragmented, this kind of habitat is being winnowed away. Collisions with deer fences (capers tend to fly low to the ground), predation by foxes and pine martens (the latter of which has made a gradual return after centuries of persecution), and human disturbance have also contributed to the capercaillie’s decline.

I remember reading an article in the mid-2000s that named the capercaillie as the bird most likely to become extinct in the UK by 2015. Thankfully, that time has passed and this large, charismatic grouse is still with us. But for how much longer? Its population has dwindled so much that some experts now fear that our capercaillies are too far gone to rebound without radical human intervention. Sadly, this icon of the Highlands is still in real danger of becoming the first bird to become extinct in Britain for a second time.

In the next British Wildlife of the Week, we’ll be looking at one of the true harbingers of spring; a bird noted for its famous call and its deceptive nature – the cuckoo.

Author

  • With a background in conservation and animal behaviour studies, Jason's passion lies in the natural world. He adores all things nature and enjoys nothing more than spotting rare and interesting species out in the wild. He has also worked in a zoo and knows plenty about keeping the animals inside our homes healthy and happy, too.

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