Grouse
| Grouse | ||||||||||||
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Capercaillie ( Tetrao urogallus ) |
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| Systematics | ||||||||||||
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| Tetraoninae | ||||||||||||
| Vigors , 1825 |
The grouse (Tetraoninae) are a subfamily of the pheasant-like . They are chicken birds of the northern hemisphere, which are adapted to cold climates. Most of the species inhabit high arctic regions or the high mountains. Even with long-term extremely nutrient-poor food from z. B. needles or buds they can survive the winter there. Well-known species are the capercaillie , the black grouse and the ptarmigan .
features
The typical hen birds are grouse of plump and stocky stature with a short neck, short legs and a short beak. The body length ranges from 30 to 90 cm, the weight from 260 g to 6 kg. The smallest species are the hazel grouse, the largest grouse is the male capercaillie.
The wings are short and rounded. They enable energy-sapping flight with fast wing flapping and short gliding phases, so that a wave-shaped flight path is created. The forest-dwelling species use this ability extremely rarely. Often they just fly from the ground to a higher branch, for example on the run from predators. Grouse of the grasslands also cover longer distances, exceptionally up to 30 km. However, this is rare, even with these species flights rarely lead over distances of more than 200 m.
As an adaptation to the cold habitats, grouse have extremely dense plumage. The feathers have a very large second shaft (aft shaft). The plumage of the hazel grouse makes up 22% of the total body weight. The nostrils and feet are also feathered up to the base of the toes, and in the ptarmigan even the toes themselves. This is not only a protection against the cold, but also prevents sinking into the snow.
The color of the plumage is dominated by gray and brown tones. By means of stripes, spots and scale patterns, a color adaptation to the underground is often achieved ( camouflage ). The males of the genus Tetrao , which have black plumage, are an exception . The protruding bulges above the eyes, called "roses", stand out in color. These are red and much more pronounced in the male; in females they are usually hidden under the feathers. In courtship these bulges swell and become even brighter.
A peculiarity is the seasonally changing plumage of the ptarmigan. In winter their plumage turns white so that enemies can hardly make out them on the snow. To perfect camouflage, other species often have different morphs . Hazel grouse have a gray and a reddish-brown morph, which are particularly common where they match the forest floor in terms of color.
The sexual dimorphism is extremely in some species, virtually non-existent in others. In the case of snow grouse and hazel grouse, the sexes can hardly be distinguished. In the black grouse and capercaillie, however, the males are much larger and heavier than the females. A capercaillie, for example, can weigh 6 kg, while a hen weighs no more than 2 kg.
The length of the bowel is related to the nutrient-poor diet. The appendix in particular is extraordinarily long - it is 60 to 140% of the length of the rest of the digestive tract (for comparison: in quail it is 35%). The goiter and gizzard are also enlarged .
An enlarged windpipe enables the grouse to call particularly far, which can be heard 3 to 4 km away. In some species (prairie chicken, rock mountain grouse), air-filled throat sacs also play a role in the generation of sound. The females are particularly fond of shouting, while the males often limit themselves to grunting, hissing and cackling sounds. Another specialty is the hazel grouse, whose whistling song is more reminiscent of a songbird than a hen bird.
In addition to the vocal sounds, other sounds such as loud beating of the wings ("burren"), fanning out the tail or stamping with the feet are important. These are mainly used during courtship .
distribution and habitat
Grouse are birds of the Holarctic and inhabit cold and temperate regions here. Typical habitats are the taiga , the tundra and high mountains of the temperate zones. One genus ( Tetrao ) is restricted to the Palearctic , three to the Nearctic . The remaining three are found in both North America and Eurasia.
The habitats of the most important species are:
- arctic tundra and mountains above the tree line: ptarmigan. The Ptarmigan has the most extreme habitats here, which occurs even on Svalbard as well as on the northern coasts of Greenland and Siberia and which also overwinters here.
- Taiga, pure coniferous forests: fir grouse, capercaillie, sickle grouse
- Deciduous or mixed forests: hazel grouse, collar grouse
- Moors, heaths, light forests: black grouse, tail grouse
- Prairie: mugwort, prairie chicken
Grouse are usually resident birds that are not very mobile. An exception are the ptarmigan, which migrate south from the northernmost regions of their range. However, the distances covered are a few hundred kilometers at most.
Way of life
activity
Although grouse are diurnal, they are rarely seen because of their hidden way of life. They show their greatest activity at dusk; This is also the time for foraging for food, which only takes one to two hours a day. Resting places are in hidden places, e.g. B. in dense shrubs. In winter, caves are dug in the snow with their feet. To do this, the chicken first digs vertically downwards and then digs a horizontal passage two to three times its body length. The ceiling above the snow chamber is only about 5 cm thick. The entrance tunnel is closed behind the bird, the oxygen supply is ensured through a small beak hole in the ceiling. The snow caves allow survival even at outside temperatures of −50 ° C; under such conditions the temperature in a hazel grouse's snow cave is only 0 ° C.
Among the grouse there are both distinct solitary animals (hazel grouse) and very sociable species (prairie grouse).
nutrition
Grouse's diet is predominantly vegetable. In the prairie fowl and the small prairie fowl, insects make up 50% of the diet, in all other species insects are only eaten by young birds and hardly at all by adults.
In summer the grouse feeds mainly on flowers, berries, fruits and leaves, whereas the seeds typical of partridges are not eaten. In winter, on the other hand, the diet becomes very one-sided, which is related to the small spectrum of available food. Most of all, needles and buds are eaten. Such a one-sided diet, which also contains only a low physiological calorific value and few proteins , is quite rare in the bird world. This diet is made possible by the lack of movement in the grouse and the anatomy of their digestive system. The preparation of the food takes place mainly in the paired appendix, the length of which often exceeds that of the small intestine. The absorbent surface of the caecum is greatly increased by 7 to 10 folds protruding into the lumen .
All grouse ingest gastroliths to aid digestion. A deficiency in gastroliths can be fatal to grouse in winter.
Reproduction
There are numerous different reproductive strategies within the grouse. The black grouse, the prairie grouse and the mugwort belong to the polygynous species in which several males gather in arenas ( leks ) and present them to the females. In contrast, the ptarmigan and hazel grouse are strictly monogamous . There are also several intermediate stages, such as the capercaillie, which is polygynous but does not perform courtship in leks.
The black grouse usually collects six to twelve males in one lek, the prairie chicken eight to nine, and the mugwort grouse even up to 400 individuals. Within such an arena, each male defends his own territory. For the mugwort, this is no larger than 1 m². The most desirable places are in the center, where the territories are the smallest. The courtship comprises a large number of ritualized gestures such as nodding the head, spreading wings, raising and shaking the tail, stamping with the feet and jumping into the air. In the mugwort, this is accompanied by sounds that are made when the air sacs are suddenly emptied. The females then make a decision and mate with a specific male. In the prairie chicken, a single male performs 71 to 89% of all copulations. There is just such an imbalance in the leks of mugwort, where 90% of copulations are carried out by only 10% of the males.
The males do not participate in the breeding business, so that the females are completely on their own after copulation. The hen first looks for a nesting place. The nest is almost always made on the ground, often hidden under bushes. For this purpose, a 15 to 25 cm wide recess is dug in the earth or a natural recess is used. It is laid out with twigs, grasses and leaves. The six to twelve eggs have a size of 4 × 2.9 cm (hazel grouse) to 5.7 × 4.2 cm (capercaillie) and are usually yellowish in color, with some species also reddish or greenish. They have black or brown spots.
The brood lasts 21 to 26 days. The female sits motionless on the nest for most of the time and only leaves it during dusk to look for food. Concealment and motionlessness are the only protection the grouse from predators. Despite the poor visibility, the open grassland species lose at least 50% of all broods to predators .
The young are pronounced fleeing nests who can immediately run and eat independently and are able to fly after ten days. Nevertheless, they are dependent on the company of their mother, who offers them protection from the cold and rain under the wings. At an alarm call from the hen, the boys run away in different directions. In order to distract predators, the hens also fake injuries. Occasionally they protect their young by attacking a predator. Nevertheless, around half of all young birds die during the first few months from extreme weather or predators.
The life expectancy of the grouse is extremely short. A capercaillie only lives two years on average. For the hazel grouse, only ten months are given as the average lifespan.
Enemies
The main enemies of the grouse are mammals, martens , lynxes , foxes and wolves , and birds of prey and owls . The hawk has specialized in grouse in large parts of the northern Holarctic. For the hazel grouse, the collar grouse and the rock mountain grouse, it is the most important enemy.
Tribal history
Grouse has been known to be fossilized since the Miocene . The oldest known species is Paleoalectoris incertus from the lower Miocene of North America. Numerous recent genera have already been fossilized: Tympanuchus since the Miocene, Tetrao since the Pliocene , and Bonasa , Lagopus and Dendragapus since the Pleistocene .
The molecular clock suggests that grouse split off from the rest of the hen birds about 28 million years ago.
Systematics
In older literature, grouse are often found in the rank of a separate family Tetraonidae. However, this is not tenable, since the pheasant-like species , which are also listed in the family rank, would then be paraphyletic in relation to the grouse. The grouse share the feature of the missing abductor of the second toe with the king fowl ( Tetraogallis ) , so that close relatives of the grouse can be assumed to be in them.
There is no doubt about the monophyly of the grouse. The classic division into genera and species follows:
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Falcipennis Falcipennis
- Siberian grouse , Falcipennis Falcipennis , eastern Siberia
- Coal Grouse , Falcipennis canadensis , boreal coniferous forests of North America
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Dendragapus
- Rock Mountain Grouse , Dendragapus obscurus , Rocky Mountains and Cascade Range
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Ptarmigan ( lagopus )
- Red grouse , Lagopus lagopus , boreal tundra
- Ptarmigan , Lagopus muta , boreal tundra, high mountains of Eurasia
- White-tailed Ptarmigan , Lagopus leucura , Alaska , British Columbia , Rocky Mountains
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Black grouse ( Lyrurus )
- Black Grouse , Lyrurus tetrix , Northern Eurasia
- Caucasian Black Grouse , Lyrurus mlokosiewiczi , Caucasus
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Capercaillie ( Tetrao )
- Capercaillie , Tetrao urogallus , northern Eurasia
- Stone capercaillie , Tetrao parvirostris , eastern Siberia, northern Mongolia
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Hazel Grouse Tetrastes
- Hazel Grouse , Tetrastes bonasia , northern Eurasia
- Black-breasted hazel grouse or Chinese hazel grouse , Tetrastes sewerzowi , Central China
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Bonasa
- Ruffed grouse , Bonasa umbellus Northern North America
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Mugwort Centrocercus
- Mugwort , Centrocercus urophasianus , western North America
- Gunnison sagebrush , Centrocercus minimus , southwestern Colorado
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Prairie chickens , tympanuchus
- Grouse , Tympanuchus phasianellus , northern North America
- Prairie Chicken , Tympanuchus cupido , central USA
- Small prairie chicken , Tympanuchus pallidicinctus , south-central USA
The Gunnison mugwort, which was previously considered a subspecies of the mugwort, was only raised to the rank of its own species in 2000.
Molecular genetic studies showed in 2002 that the genera Bonasa and Falcipennis are probably not monophyletic. The results can be summarized in the following cladogram :
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The sickle chicken is missing from the cladogram due to contradicting results. A position near the mugwort is seen as one possibility.
Humans and grouse
Grouse hunt probably begins with the arrival of humans in Eurasia. Bones of grouse have already been recovered from paleolithic garbage pits. The meat of these chickens still plays an important role in Nordic peoples such as the Sami or Eskimos . The domestication of a species, however, has never been attempted according to current knowledge.
Over the centuries, hunting has resulted in the populations of many species being greatly reduced. By the late 1970s, 8.5 million grouse were shot annually in North America. In Europe the numbers were just as high at the beginning of the 20th century. Today, capercaillie, black grouse and hazel grouse have become a rarity in central and northern Europe. The NABU leads on its Red List of breeding birds in Germany capercaillie and black grouse as an endangered species, the hazel grouse as endangered.
Due to the secured populations in the forests of Siberia , however, the three aforementioned species are globally not endangered. Three species are listed as endangered by the IUCN . The Gunnison mugwort is endangered because of its small, fragmented range and declining population. The prairie chicken has also been endangered since 2004 . The once extremely common bird has suffered a dramatic decline in populations , mainly due to the conversion of the prairie into agricultural land. The small prairie chicken had to be classified as endangered as early as 2000.
Sources and further information
Sources cited
Most of the information in this article is taken from the source given under literature; the following sources are also cited:
- ↑ a b Bernhard Grzimek (Ed.): Grzimeks Tierleben , Volume 7: Vögel 1 . dtv, 1979
- ↑ RL Potapov, VE Fling (ed.): Handbook of the birds of the Soviet Union. Volume 4: Galliformes, Gruiformes. Aula Verlag, Wiesbaden 1989, ISBN 3-89104-417-8 , p. 103
- ↑ a b Derek E. Dimcheff, Sergei V. Drovetski, David P. Mindell: Phylogeny of Tetraoninae and other galliform birds using mitochondrial 12S and ND2 genes . In: Molecular Phylogenetics and Evolution 2002, No. 24, pp. 203-215
- ↑ Jessica R. Young, Clait E. Braun, Sara J. Oyler-McCance, Jerry W. Hupp, Tom W. Quinn: A new species of sage-grouse (Phasianidae: Centrocercus) from southwestern Colorado . In: The Wilson Bulletin 2000, Vol. 112, No. 4, pp. 445-453
- ^ Red list of breeding birds in Germany . NABU, December 9, 2008
- ↑ Centrocercus minimus in the endangered Red List species the IUCN 2011. Posted by: BirdLife International, 2009. Accessed November 17, 2011th
- ↑ Tympanuchus cupido in the endangered Red List species the IUCN 2011. Posted by: BirdLife International, 2008. Accessed November 17, 2011th
- ↑ Tympanuchus pallidicinctus in the endangered Red List species the IUCN 2011. Posted by: BirdLife International, 2008. Accessed November 17, 2011th
literature
- Josep del Hoyo et al .: Handbook of the Birds of the World. Volume 2: New World Vultures to Guinea Fowl. Lynx Edicions, 1994, ISBN 84-87334-15-6 .
- Grouse - Status Survey and Conservation Action Plan 2006–2010 . (PDF; 125 p .; 5.1 MB) IUCN
