The western capercaillie (Tetrao urogallus), also known as the wood grouse, heather cock or capercaillie /ˌkæpərˈkeɪli/, is the largest member of the grouse family. The largest known specimen, recorded in captivity, had a weight of 7.2 kg (16 lb). Found across Europe and Asia, it is renowned for its mating display.
The species was first described by Linnaeus in his Systema naturae in 1758 under its current binomial name.
Its closest relative is the black-billed capercaillie, Tetrao parvirostris, which breeds in the larch taiga forests of eastern Russia and parts of northern Mongolia and China.
The races show increasing amounts of white on the underparts of males from west to east, almost wholly black with only a few white spots underneath in western and central Europe to nearly pure white in Siberia, where the black-billed capercaillie occurs. Variation in females is much less. The native Scottish population, which became extinct between 1770 and 1785, was probably also a distinct race, though it was never formally described as such; the same is also likely of the extinct Irish population.
Western capercaillies are known to hybridise occasionally with black grouse (these hybrids being known by the German name Rackelhahn) and the closely related black-billed capercaillie.
Male and female western capercaillie—the cocks and the hens—can easily be differentiated by their size and colouration. The male bird (or cock) is much bigger than the female (or hen). It is one of the most sexual dimorphic in size of living bird species, dimorphism only exceed by the larger types of bustards and a select few members of the pheasant family. Cocks typically range from 74 to 85 cm (29 to 33 in) in length with wingspan of 90 to 125 cm (35 to 49 in) and an average weight of 4.1 kg (9.0 lb). The largest wild cocks can attain a length of 100 cm (39 in) and weight of 6.7 kg (15 lb). The largest specimen ever recorded in captivity had a weight of 7.2 kg (16 lb). The weight range of 75 wild cocks was found to range from 3.6 to 5.05 kg (7.9 to 11.1 lb). The body feathers are coloured dark grey to dark brown, while the breast feathers are dark metallic green. The belly and undertail coverts vary from black to white depending on race (see below).
The hen is much smaller, weighing about half as much as the cock. The capercaillie hen's body from beak to tail is approximately 54–64 cm (21–25 in) long, the wingspan is 70 cm (28 in) and weighs 1.5–2.5 kg (3.3–5.5 lb), with an average of 1.8 kg (4.0 lb). Feathers on the upper parts are brown with black and silver barring, on the underside they are more light and buffish-yellow.
Both sexes have a white spot on the wing bow. They have feathered legs, especially in the cold season for protection against cold. Their toe rows of small, elongated horn tacks provide a snowshoe effect that led to the German family name "Rauhfußhühner", literally translated as "rough feet chickens".
These so-called "courting tacks" make a clear track in the snow in winter. Both sexes can be distinguished very easily by the size of their footprints.
There is a bright red spot of naked skin above each eye. In German hunters' language, these are the so-called "roses".
The small chicks resemble the hen in their cryptic colouration, which is a passive protection against predators. Additionally, they wear black crown feathers. At an age of about three months, in late summer, they moult gradually towards the adult plumage of cocks and hens. The eggs are about the same size and form as chicken eggs, but are more speckled with brown spots.
It is a sedentary species, breeding across northern parts of Europe and western and central Asia in mature conifer forests with diverse species composition and a relatively open canopy structure.
At one time it could be found in all the taiga forests of northern and northeastern Eurasia within the cold temperate latitudes and the coniferous forest belt in the mountain ranges of warm temperate Europe. The Scottish population became extinct, but has been reintroduced from the Swedish population; in Germany it is on the "Red list" as a species threatened by extinction, and is no longer found in the lower mountainous areas of Bavaria; in the Bavarian Forest, the Black Forest and the Harz mountains numbers of surviving western capercaillie decline even under massive efforts to breed them in captivity and release them into the wild; in Switzerland, in the Swiss Alps, in the Jura, in the Austrian and Italian Alps . The species is extinct in Belgium. In Ireland it was common until the seventeenth century, but died out in the eighteenth. In Norway, Sweden, Finland, Russia and Romania populations are quite big, and it is quite a common bird to see in the forested regions of these countries.
The most serious threats to the species are habitat degradation, particularly conversion of diverse native forest into often single-species timber plantations, and to birds colliding with fences erected to keep deer out of young plantations. Increased numbers of small predators that prey on capercaillies (e.g. red fox) due to the loss of large predators who control smaller carnivores (e.g. gray wolf, brown bear) also cause problems in some areas.
The western capercaillie lives on a variety of food types, including buds, leaves, berries, insects, grasses and in the winter mostly conifer needles; you can see the food remains in their droppings, which are about 1 cm (0.39 in) in diameter and 5–6 cm (2.0–2.4 in) in length. Most of the year the droppings are of solid consistency, but with the ripening of blueberries, these dominate the diet and the faeces become formless and bluish-black.
The western capercaillie is a highly specialized herbivore, which feeds almost exclusively on blueberry leaves and berries along with some grass seeds and fresh shoots of sedges in summertime. The young chicks are dependent on protein-rich food in their first weeks and thus mainly prey on insects. Available insect supply is strongly influenced by weather—dry and warm conditions allow a fast growth of the chicks, cold and rainy weather leads to a high mortality among them.
During winter, when a high snow cover prevents access to ground vegetation, the western capercaillie spends almost all day and night in trees, feeding now on coniferous needles of spruce, pine and fir as well as on buds from beech and rowan.
In order to digest this coarse winter food the birds need grit, small stones or gastroliths which they actively search for and devour. Together with their very muscular stomach, these gizzard stones function like a mill and break needles and buds into small particles. Additionally, western capercaillie have two appendixes which grow very long in winter. With the aid of symbiotic bacteria, the plant material is digested there. During the short winter days the western capercaillie feeds almost constantly and produces a pellet nearly every 10 minutes.
The abundance of western capercaillie depends—like in most other species—on habitat quality, it is highest in sun-flooded open, old mixed forests with spruce, pine, fir and some beech with a rich ground cover of Vaccinium species.
Spring territories are about 25 hectares (62 acres) per bird. Comparable abundances are found in taiga forests. Thus, the western capercaillie never had particularly high densities, despite the legends that hunters like to speculate about. Adult cocks are strongly territorial and occupy a range of 50 to 60 hectares (120 to 150 acres) optimal habitat. Hen territories are about 40 hectares (99 acres). The annual range can be several square kilometres (hundreds of hectares) when storms and heavy snowfall force the birds to winter at lower altitudes. Territories of cocks and hens may overlap.
Western capercaillie are diurnal game, i.e. their activity is limited to the daylight hours. They spend the night time in old trees with horizontal branches. These sleeping trees are used for several nights, they can be mapped easily as the ground under them is covered by pellets.
The hens are ground breeders and spend the night on the nest. As long as the young chicks cannot fly the hen spends the night with them in dense cover on the ground. During winter the hens rarely go down to the ground and most tracks in the snow are from cocks.
The species was first described by Linnaeus in his Systema naturae in 1758 under its current binomial name.
Its closest relative is the black-billed capercaillie, Tetrao parvirostris, which breeds in the larch taiga forests of eastern Russia and parts of northern Mongolia and China.
The races show increasing amounts of white on the underparts of males from west to east, almost wholly black with only a few white spots underneath in western and central Europe to nearly pure white in Siberia, where the black-billed capercaillie occurs. Variation in females is much less. The native Scottish population, which became extinct between 1770 and 1785, was probably also a distinct race, though it was never formally described as such; the same is also likely of the extinct Irish population.
Western capercaillies are known to hybridise occasionally with black grouse (these hybrids being known by the German name Rackelhahn) and the closely related black-billed capercaillie.
Male and female western capercaillie—the cocks and the hens—can easily be differentiated by their size and colouration. The male bird (or cock) is much bigger than the female (or hen). It is one of the most sexual dimorphic in size of living bird species, dimorphism only exceed by the larger types of bustards and a select few members of the pheasant family. Cocks typically range from 74 to 85 cm (29 to 33 in) in length with wingspan of 90 to 125 cm (35 to 49 in) and an average weight of 4.1 kg (9.0 lb). The largest wild cocks can attain a length of 100 cm (39 in) and weight of 6.7 kg (15 lb). The largest specimen ever recorded in captivity had a weight of 7.2 kg (16 lb). The weight range of 75 wild cocks was found to range from 3.6 to 5.05 kg (7.9 to 11.1 lb). The body feathers are coloured dark grey to dark brown, while the breast feathers are dark metallic green. The belly and undertail coverts vary from black to white depending on race (see below).
The hen is much smaller, weighing about half as much as the cock. The capercaillie hen's body from beak to tail is approximately 54–64 cm (21–25 in) long, the wingspan is 70 cm (28 in) and weighs 1.5–2.5 kg (3.3–5.5 lb), with an average of 1.8 kg (4.0 lb). Feathers on the upper parts are brown with black and silver barring, on the underside they are more light and buffish-yellow.
Both sexes have a white spot on the wing bow. They have feathered legs, especially in the cold season for protection against cold. Their toe rows of small, elongated horn tacks provide a snowshoe effect that led to the German family name "Rauhfußhühner", literally translated as "rough feet chickens".
These so-called "courting tacks" make a clear track in the snow in winter. Both sexes can be distinguished very easily by the size of their footprints.
There is a bright red spot of naked skin above each eye. In German hunters' language, these are the so-called "roses".
The small chicks resemble the hen in their cryptic colouration, which is a passive protection against predators. Additionally, they wear black crown feathers. At an age of about three months, in late summer, they moult gradually towards the adult plumage of cocks and hens. The eggs are about the same size and form as chicken eggs, but are more speckled with brown spots.
It is a sedentary species, breeding across northern parts of Europe and western and central Asia in mature conifer forests with diverse species composition and a relatively open canopy structure.
At one time it could be found in all the taiga forests of northern and northeastern Eurasia within the cold temperate latitudes and the coniferous forest belt in the mountain ranges of warm temperate Europe. The Scottish population became extinct, but has been reintroduced from the Swedish population; in Germany it is on the "Red list" as a species threatened by extinction, and is no longer found in the lower mountainous areas of Bavaria; in the Bavarian Forest, the Black Forest and the Harz mountains numbers of surviving western capercaillie decline even under massive efforts to breed them in captivity and release them into the wild; in Switzerland, in the Swiss Alps, in the Jura, in the Austrian and Italian Alps . The species is extinct in Belgium. In Ireland it was common until the seventeenth century, but died out in the eighteenth. In Norway, Sweden, Finland, Russia and Romania populations are quite big, and it is quite a common bird to see in the forested regions of these countries.
The most serious threats to the species are habitat degradation, particularly conversion of diverse native forest into often single-species timber plantations, and to birds colliding with fences erected to keep deer out of young plantations. Increased numbers of small predators that prey on capercaillies (e.g. red fox) due to the loss of large predators who control smaller carnivores (e.g. gray wolf, brown bear) also cause problems in some areas.
The western capercaillie lives on a variety of food types, including buds, leaves, berries, insects, grasses and in the winter mostly conifer needles; you can see the food remains in their droppings, which are about 1 cm (0.39 in) in diameter and 5–6 cm (2.0–2.4 in) in length. Most of the year the droppings are of solid consistency, but with the ripening of blueberries, these dominate the diet and the faeces become formless and bluish-black.
The western capercaillie is a highly specialized herbivore, which feeds almost exclusively on blueberry leaves and berries along with some grass seeds and fresh shoots of sedges in summertime. The young chicks are dependent on protein-rich food in their first weeks and thus mainly prey on insects. Available insect supply is strongly influenced by weather—dry and warm conditions allow a fast growth of the chicks, cold and rainy weather leads to a high mortality among them.
During winter, when a high snow cover prevents access to ground vegetation, the western capercaillie spends almost all day and night in trees, feeding now on coniferous needles of spruce, pine and fir as well as on buds from beech and rowan.
In order to digest this coarse winter food the birds need grit, small stones or gastroliths which they actively search for and devour. Together with their very muscular stomach, these gizzard stones function like a mill and break needles and buds into small particles. Additionally, western capercaillie have two appendixes which grow very long in winter. With the aid of symbiotic bacteria, the plant material is digested there. During the short winter days the western capercaillie feeds almost constantly and produces a pellet nearly every 10 minutes.
The abundance of western capercaillie depends—like in most other species—on habitat quality, it is highest in sun-flooded open, old mixed forests with spruce, pine, fir and some beech with a rich ground cover of Vaccinium species.
Spring territories are about 25 hectares (62 acres) per bird. Comparable abundances are found in taiga forests. Thus, the western capercaillie never had particularly high densities, despite the legends that hunters like to speculate about. Adult cocks are strongly territorial and occupy a range of 50 to 60 hectares (120 to 150 acres) optimal habitat. Hen territories are about 40 hectares (99 acres). The annual range can be several square kilometres (hundreds of hectares) when storms and heavy snowfall force the birds to winter at lower altitudes. Territories of cocks and hens may overlap.
Western capercaillie are diurnal game, i.e. their activity is limited to the daylight hours. They spend the night time in old trees with horizontal branches. These sleeping trees are used for several nights, they can be mapped easily as the ground under them is covered by pellets.
The hens are ground breeders and spend the night on the nest. As long as the young chicks cannot fly the hen spends the night with them in dense cover on the ground. During winter the hens rarely go down to the ground and most tracks in the snow are from cocks.
