Tetrao urogallus
Tetrao urogallus
The Western capercaillie (Tetrao urogallus Linnaeus, 1758) is a bird belonging to the Phasianidae family.
Systematics –
From a systematic point of view it belongs to:
Eukaryota Domain,
Kingdom Animalia,
Phylum Chordata,
Aves class,
Subclass Neornithes,
Superorder Neognathae,
Order Galliformes,
Family Phasianidae,
Subfamily Tetraoninae,
Genus Tetrao,
T. urogallus species,
The following subspecies are recognized in this species:
– Tetrao urogallus aquitanicus;
– Tetrao urogallus cantabricus;
– Tetrao urogallus karelicus;
– Tetrao urogallus lonnbergi;
– Tetrao urogallus major;
– Tetrao urogallus tardetus;
– Tetrao urogallus pleskei;
– Tetrao urogallus rudolfi;
– Tetrao urogallus uralensis;
– Tetrao urogallus urogallus;
– Tetrao urogallus volgensis.
Geographic Distribution and Habitat –
The Western capercaillie is a bird spread over a vast range that covers a large part of the Palearctic ecozona, which is constantly decreasing throughout the European continent, becoming more frequent only in the vast forests of Scandinavia and Russia. Its borders have not shrunk, but it is encountered in considerably fewer numbers.
In Italy, the species became extinct in the western Alps while it is still present in the mountainous areas of Lombardy, Veneto, Trentino-Alto Adige and Friuli.
In the Alps the capercaillie was once present continuously. Its range has undergone a strong contraction over time and is practically in extinction in the Western Alps. Its presence has also decreased in the Central Alps, where it is present only locally and with particularly low consistencies. Even in the Eastern Alps, where to date (2007) the species is still distributed with sufficient continuity, the numbers have progressively been decreasing in a worrying way. Moving from west to east, the first large populations in the Alps are found in Trentino, in particular within the Adamello-Brenta Natural Park.
Its habitat is that which goes from mountain forests to lowland ones, with tall trees – especially resinous ones – in abundantly irrigated areas rich in bushes and low shrubs with berries; it also loves swampy lands. In the Alps it lives mainly at an altitude between 1,200 and 1,700 meters, in mature coniferous forests (possibly mixed with beech), with secular plants, but with sparse density or dense with clearings, with discontinuous shrub layer. These woods were once abundant, but now, due to the reduction of silvicultural cuts, they have given way to dense woods, in which the capercaillie can no longer live.
Description –
Tetrao urogallus is a bird with presence of sexual dimorphism and in which the male measures 75-95 cm, length and female 58-68 cm. the weight is up to 5 kg in the male and up to 2 kg in the female, respectively.
It has a wingspan of 1.30 m and a 35 cm tail.
The sexual dimorphism is evident: the female has a plumage of a uniform brown color; the male has a black neck and tail, while the wings are brown, has a white spot on the shoulder and a red one above the eye; the males also show a brist beard in the throat.
The eye is brown, the periocular membrane red and the white-horny beak.
The young, from one suit to another, have various colors.
The chicks, in fact just born, are generally of a rusty-yellow color, with the reins marginalized by two longitudinal brown stripes and with a brown spot placed between them; a brown streak passes in the form of an arc above the eyes, between which two other brown-black ones can be seen, which join posteriorly; the occiput is marked backwards by a blackish band on which a stripe is arranged vertically which descends along the median line of the neck; the feathers of the back have brown and blackish spots and streaks and those of the abdomen are gray-yellow sulfur, paler on the throat. The eye is bluish, the pupil is lead-colored, the upper jaw is dark, the lower is light horn-colored; toes and claws of the paws, already covered with down, have a yellowish color.
After a few days the flight feathers begin to appear, then the feathers of the back and chest and those of the head, so that, in short, the first dress is complete. In it all the feathers of the head, of the back of the neck and of the back are blackish at the base, whitish at the tip, streaked with yellow-rust along the stem and transversely spotted with this same color and black; the remiges are black-gray with rust-yellow bands and spots, the upper coverts of the wings are similar to the feathers of the back, and the lower parts are yellow-rust with brown spots and bands.
These feathers also soon fall and the chick will have a second moult.
The head and the back of the neck become yellow-gray with brown and blackish transverse and wavy lines, the back shows the same design on a brown-rust background, the space under the eye is brownish and stained with white, the throat greyish with darker transverse margins and spots, and the anterior part of the neck yellowish-white with transverse blackish streaks and a russet margin, sometimes flanked by another blackish margin. The ingluvie is yellow-rust with whitish spots, the rest of the lower parts appear covered with white, yellowish and brown feathers, streaked transversely with a very irregular pattern. The eye is bluish, the pupil is gray, the beak is horny; the fingers are gray, and the legs are still covered with gray duvet. Up to this point, male and female wear the same colors, but in the volume there is already a difference. The female then gradually dresses the final dress without making noticeable changes, while the male wears a third dress. In it the head is gray-black with rusty shades and ashy waving on the front half, the back of the neck and the sides of the same are gray and fade insensibly into the gray-yellow of the rump; the upper part of the back is brown-rust with brown-black zigzag lines; the remiges have little acute shape and black-gray color with rust-yellow margins and spots; the feathers of the throat are whitish with darker tips, those of the anterior part of the neck whitish with blackish or ashy spots and waves; on the center of the chest all the feathers appear black with splashes and rusty spots and white tips, on the belly and on the tibias they are mixed of white and gray. The eye is black, the pupil is brown, the horny beak – lighter at the bottom and at the margin – the legs are dressed up to the base of the fingers in a grayish feather and the fingers themselves are horny.
Having reached the middle of its ordinary size, the capercaillie begins to put the feathers of the complete dress, starting from the wing and tail and continuing on the hips, chest and other parts of the body. They grow so slowly that, by the time the habit is completed, the bird has already reached its full development. In late autumn the young family is divided by sexes, the females stay with their mother, the males wander around in company, make their voices heard from time to time and sometimes fight: in the following spring they already have all the adult costumes.
As for the calls of the Tetrao urogallus, the female emits noises like the pheasant, similar to a “koc”; the male, on the other hand, has a much more modulated song, which begins with a kind of “ticap” and ends with a “pop” and other notes.
Biology –
The Western capercaillie begins the mating season towards the period of April-May, in which the males stage, in the semi-open places of the forest, spectacular love parades to attract the females, with singing performances, ritual movements and the display of tail feathers .
The cedar gallo is undoubtedly one of the gallinaceous that shows the greatest and most characteristic activity in the mating period; this manifestation begins when the forest is still silent and for the other birds spring has not yet appeared; its singular games begin as soon as the first dawns have appeared on the horizon
In these games, the birds seem to have completely lost their hearing, probably due to the strong pressure exerted on the surrounding atmosphere and the extraordinary excitement by which they are dominated. It is a form of hyperactivity that reaches the most singular manifestations: the bird goes so far as to face serious dangers, some specimens are not afraid to place themselves in the areas frequented by man and to approach him, chase him, peck him, completely denying his own shy nature. Certain superstitions even speak of an evil spirit entering the animal’s body. The capercaillie does not always reach these excesses, but it is certain, however, that in any case it shows off a strongly warlike nature. Adults do not tolerate that young people settle in their neighborhood, and fight like real knights, where necessary, to the death: young people become shy and sing softly when they know that there is some old champion nearby.
In this epoch it is also easier to hear the cry of these birds, very lively when the day comes and sensitive even at night. At dawn the males calm down and go to the females who are amusing themselves at some distance: after having reached them, they renew their cries, turn around them and finally force them to yield to their wishes. Sometimes the females show a preference for this or that male, and from this arises fierce fights; some males fail to reach their goal and cry out for love again in May, June and even July. After a few weeks, the grouse return satisfied to their seats and the females begin to build the nest. Each chooses a suitable place and departs from the others; the nest consists of a shallow depression coated roughly with dry twigs and contains a variable number of eggs in relation to the age of the mother who, if young, lays no more than six or eight, if adult, from ten to twelve. The eggs are relatively small, with shiny and thin shell and on a gray-yellow or yellow-brownish background; they are scattered with spots and darker spots. They are hatched with touching care by the mother who does not leave the nest even in case of very serious danger and, especially in the last days, she can be easily grasped with the hands. Unfortunately, it is not always prudent enough to choose the places less exposed to birds of prey.
After mating, the female lays 5 to 10 eggs which are placed in a depression in the ground and sometimes in the shelter of a bush or a young conifer with low branches.
The hatching period lasts about 4 weeks.
The newborns, just born, are immediately able to follow their mother; the brood melts in autumn.
After a few weeks, the newborns are already covered with enough feathers and feathers to be able to rise in the air, but they do not wear the full dress until much later, according to a succession of mutations as described above.
The success of the broods depends on the meteorological conditions in the reproductive period and above all on interference from its environment (forestry activities, tourist activities – e.g. work on the slopes and ski facilities, etc.)
Ecological Role –
The Western capercaillie is a sedentary bird that moves from its usual locations only by the occurrence of severe colds and abundant snowfalls that make it impossible to find food: but as soon as the season improves, it resumes its way to favorite places.
In some cases, when its territory is completely covered by snow, it retreats to the branches of trees, and spends long periods there feeding on leaves.
In general, he spends his days on the ground, in continuous runs among the scrub and low shrubs where he goes in search of food, taking off only in front of something surprising.
Its diet consists of tree buds, leaves, berries, seeds, clover and insects. In the period of love, the capercaillie is satisfied with coarser foods, and seems to hardly want to bother to look for food; in this it differs from the female, and from this comes perhaps that tenacious fibrousness which makes the flesh of the adult male almost inedible, while those of the female are very delicate and tasty.
In winter it eats mainly on conifer needles, in spring on buds and shoots of the undergrowth, in summer and autumn on berries and fruits such as raspberries, strawberries, blueberries, currants, bearberry. The females and chicks also feed on insects and other invertebrates.
To digest food it needs sand or very fine gravel, and it approaches water several times during the day.
As already mentioned, this bird, even if present on a vast range, is constantly decreasing and for this reason this species is protected by various European and national regulations.
Among the natural enemies of this bird we remember the fox and the goshawk, which must, however, beware of many other adversaries. The adults, very cautious, defend themselves well, but the young and even more the eggs are often destroyed.
The causes of decrease of the Tetrao urogallus, as for those of the other alpine grouse, are unclear and probably multiple (the main ones seem to be the anthropic disturbance linked above all to tourist flows and climate change). Precisely to enter into the merits of these causes, the Adamello-Brenta Natural Park, in 2007, with the collaboration of the Forests and Fauna Service of the Autonomous Province of Trento, launched a multi-year research on galliformes, and in particular on the Tetrao urogallus.
At the moment, however, according to the IUCN, this species is classified as at minimal risk of extinction.
Guido Bissanti
Sources
– Wikipedia, the free encyclopedia.
– C.Battisti, D. Taffon, F. Giucca, 2008. Atlas of nesting birds, Gangemi Editore, Rome.
– L. Svensson, K. Mullarney, D. Zetterstrom, 1999. Guide to the birds of Europe, North Africa and the Near East, Harper Collins Publisher, UK.