The capercaillie (Tetrao urogallus), the largest of the grouse family, was exterminated in Scotland in 1785. Reintroduced during the nineteenth century, it is once again facing a crisis.
Global distribution
The capercaillie is a resident in northern Europe and Asia in coniferous forests, especially in hills and mountains, and in the mountains of central eastern Europe. It also has population outposts in the Pyrenees and Scottish Highlands.
Distribution in Scotland
The capercaillie is one of three bird species that is restricted to pinewood habitat in northern Scotland (the other two are the crested tit (Parus cristatus), and the Scottish crossbill (Loxia scotia)). It prefers old, open pine forests with lush ericaceous ground cover, though in summer it is occasionally found in mature oakwoods.
Today all the capercaillie in Scotland originate from Swedish stock, as they became extinct in Scotland in 1785. Prior to its extinction, it was once common and widespread, but as the forests were felled it became rare until the last pair were shot, reputedly for a royal wedding banquet at Balmoral. Unsuccessful attempts were made to reintroduce the capercaillie for sport by the Earl of Fife at Mar Lodge early in the nineteenth century. In 1837, however, capercaillie were successfully reintroduced by Lord Breadalbane at Taymouth Castle and they rapidly recolonised the local pinewoods. Soon other reintroductions were made in various pinewood localities in Scotland, using descendants of the original Taymouth introductees, combined with additional capercaillie brought from Scandinavia.
Unfortunately today capercaillie are once again facing a crisis. Recent figures from the RSPB/Scottish Natural Heritage joint survey indicate that Scottish capercaillie numbers have declined to around 1,000 individuals, a halving of the population in the last five years. This serious reduction is due to a combination of factors. Decrease and fragmentation of suitable habitat is an important problem, not only from the direct effects of habitat loss but also from the ‘edge effect’. This effect has provided access to the pinewood habitat for an increased numbers of predators, such as foxes, stoats and crows. Deer fencing is another hazard, with low flying birds hitting the fences. A radio tagging study by RSPB and the Institute of Terrestrial Ecology estimated that “from 29 capercaillie fitted with radio transmitters, it was estimated that annual mortality from collisions with fences was 32%“*. In addition to the adult population being decimated, the new generation of capercaillies are struggling to survive, as recent years have seen wet and cool weather conditions in the early summer when the chicks are born. This has led to high chick mortality rates, resulting in older birds not being replaced when they die. Another problem that has not been quantified, but which is felt to be an increasingly contributory factor by various researchers, is disturbance by people, especially during the displaying and mating season.
Capercaillie make full use of a varied pinewood habitat. In winter the birds need pine trees for food and in summer good ground cover of shrubby vegetation for nesting and chick rearing. This reliance on, and exacting needs of, a varied but specific habitat led to their extinction in the past when the forests were destroyed by people. Though hunting played a part, it probably only accelerated the inevitable process. Today, as detailed above, capercaillie are under threat from various factors but not least because of reduction of their favoured habitat. Research has shown that capercaillie densities are highest in semi-natural woodland. Despite this, 60% of the population are found in plantation type woodlands, because there is not enough undisturbed native pinewood habitat left to support a majority of the capercaillie numbers.
The dramatic decline of these birds has focused attention on their habitat requirements and has shown that they act as a good indicator of the health and extent of varied mature forest cover. Unlike the first demise of the capercaillie in Scotland, this time the problem has been recognised and carefully monitored. It is not too late yet for the capercaillie, and the combined action that is being taken by a variety of organisations should ensure that we will not lose this magnificent bird from the Caledonian Forest again.
*Assessment of Bird Collisions with Deer Fences in Scottish Forests, D. Baines and R. W. Summers, 1997
Capercaillie are not only facing a demise in Scotland but also in other parts of their range, due mainly to the same variety of problems as we have here. It is recognised at an international level as a species worthy of protection under the European Bird Directive. In Britain a Species Action Plan has been drawn up by the Capercaillie Steering Group, which is made up of various government and non-government organisations.
The male capercaillie can weigh up to 4 kg, making it the largest member of the grouse family. At first glance the male appears to be a large turkey-sized, dark slate-grey bird. Closer inspection will reveal the chocolate coloured back and wings, a metallic green shield on the breast, white markings on the wing and tail and a splash of crimson above the eye. The smaller female, less than half the weight of the male, needs good camouflage when she is sitting on eggs and looking after her brood. Her barred shades of dark and rufous brown blend with a chestnut breast flecked with white, which is more extensive on her belly.
Capercaillie can be surprisingly nimble when climbing the branches of pine trees. They are renowned for being shy and very difficult to see except during the displaying season. If they are disturbed they will initially freeze; if flushed they take off with a characteristic crashing as the bird leaves the foliage, and they can fly with surprising agility between trees, even in dense forest.
In summer the capercaillie feed close to and even on the ground. Their diet includes buds, shoots, seeds and berries. This dictates their preference for open pinewood habitats with lush ground cover of heather and dwarf shrubs that provide not only ample food but protection too. In winter they are arboreal and pine needles are eaten by nipping off the leading shoots of conifers.
Male capercaillie have a complex display that they use to attract females to mate with them in the Spring. This display is usually a communal affair at a traditional site known as a lek, which originates from the Norse word meaning ‘to dance’. They may also use a transient arena or even display from trees in response to the presence of a female. Initially the display song involves tapping and gurgling which accelerates to a drum roll that earned the bird his Gaelic name, capull-choille, the horse of the woods. This drum roll is followed by a noise which rather resembles a cork being pulled out of a bottle, and the final song phase involves alternating gurgling and wheezing. To many people, this soft dawn song is rather surprising for such a large bird, especially as the purpose is to attract hens from afar. However, it is now recognised that parts of the song are below the human range of hearing. The subsonic part of the call is thought to carry well over distance and to be audible to other capercaillie.
During the song the male has his tail held vertical and fanned out, his beak pointing skywards and the wings held out and drooped. In this posture the cock may slowly strut forward and often does a `flutter-jump’ following the cork pop part of the song. This involves leaping rapidly with noisily flapping wings, a brief glide and fluttering or crashing back to the ground (see illustration below). Once the hens have been drawn in to the lekking area, the cock’s display becomes more intense, but less vigorous with the flutter-jumping usually stopping.
A male capercaillie flutter-jumping |
Direct confrontation between competing suitors frequently occurs and has been described as a “vicious explosion of buffeting wings and snapping bills – the pair may not cease until one is dead”. By the end of the mating season the dominant alpha males often sport various cuts and bald patches from these fights. During the mating season the males are very aggressive and have been known to attack bird watchers! Older males are the biggest with broader tails than younger birds and are usually dominant, therefore mating with more females.
The capercaillie hen lays five to eight eggs in early May. Her nest is a scrape on the ground, frequently in a hollow under a tree. The cock plays no part in the brooding or rearing of the chicks. The precocious buff and reddish chicks all hatch at the same time. At this point they are very vulnerable to a wide range of predators and at a young age they are able to fly short distances over the heather. The hen is very protective and keeps her brood close to her with muted contact calls. Their diet for the first two to three weeks is mainly insects, especially caterpillars of moths and sawflies. After this their diet resembles the adult’s and is herbivorous. After about four months the chicks become independent.
Generally the females and young, once they have matured, will live in small flocks while the adult males are solitary. After the first winter the young males often become intolerant of the females and, like red deer, the mixed flocks will split into same-sex groups.
Being herbivorous, capercaillie have a profound effect on the vegetation they browse upon. For example, they act as agents for the dispersal of the berries they eat, especially for the blaeberry (Vaccinium myrtillus). In the past, capercaillie have not been highly regarded by foresters because of their winter habit of eating the leading shoots of conifers. In a sparsely wooded area, or where growth is less vigorous, this can check the growth and trees can take up to five years to recover. However, in a large native forest this damage is negligible and indeed adds to the variety and beauty of the shapes of Scots pine trees. Capercaillie will sometimes take dust baths to rid themselves of ectoparasites. Wood ant nests provide a very suitable place for this activity, which is unfortunately detrimental to the ants’ home.
Even the most protective mother will lose a chick to a predator. This is not surprising as there are a wide variety of animals that regard a capercaillie chick as good prey – stoat (Mustela erminea), fox (Vulpes vulpes), pine marten (Martes martes), wildcat (Felis sylvestris) and sparrowhawk (Accipiter nisus) amongst others. Adults will also be wary, but one anecdote of a blustering male slinking away having spotted a pair of golden eagles (Aquila chrysaetos) that could only just be seen through binoculars, demonstrates they must not be easy prey to catch.
