Red-crowned crane
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Red-crowned crane ( Grus japonensis ) |
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| Grus japonensis | ||||||||||||
| ( Statius Müller , 1776) |
The Red-crowned crane ( Grus japonensis ), more rarely also known as the red-crowned crane , is one of the most endangered species in the crane family . The low point of the population of this species found in East Asia was probably in the years immediately after the Second World War . The population has since recovered in some areas. In the last 60 years, however, large parts of the habitat have been converted into agricultural areas. Around 1,700 to 2,000 specimens lived in the wild by the end of the 20th century. The IUCN therefore classifies this species as critically endangered. In the People's Republic of China , it is now one of the “ first-degree protected species ” together with the giant panda and the snub nose .
Red-crowned cranes are a decidedly aquatic species that need a dense mosaic of reeds and free, shallow water zones during their breeding season. They do not have long winter trains. The populations on the East Asian mainland migrate to coastal regions. The red- crowned cranes that breed on the Japanese island of Hokkaidō are largely resident birds .
description
Appearance of adult red-crowned cranes
The red-crowned crane reaches a height of 1.5 meters and a weight of up to ten kilograms. He is so much greater than the in Central Europe occurring gray crane . Its wingspan is 2.2 to 2.5 meters. Females are overall slightly smaller than males. There is no gender or seasonal dimorphism . Life expectancy is around 30 years.
The entire body plumage, the wings of the hand, wing covers, armpits and control feathers are pure white. The chin, throat, and the top half of the neck are black. A wide, white band runs from the eye on each side to the neck, which unites there and runs down the back of the neck. The red-crowned crane shows isolated black feathers on the bare black skin of the forehead. These can also be found on the rough, warty crest of its crimson crown.
Similar to Gray Crane, monks , Schwarzhals- and whooping crane that crimson stain is emphasized by the black and white pattern of head feathers. During the cold season or during a migratory flight, the crown of the red-crowned crane can appear darker because it is then less supplied with blood. Occasionally it is also hidden under the white neck feathers that can be pulled forward like a hood. The very long legs allow him to wade effortlessly through shallow water and bank edging. The beak is pointed and perfectly adapted to his hunting techniques.
Down and youth dress
Downy young have short and dense downs in their first dress, which are yellowish reddish brown on the upper side of the body. The front and rear backs are the darkest, there are light spots on the base of the wing. The underside of the body is light reddish yellow. The second dune dress is similar to the first but is lighter and grayer. The light spots on the wing base stand out less noticeably from the rest of the dress.
The youth dress is put on at the end of August at the age of about three months. Young birds are reddish brown on the neck and head. The white body feathers have broad red-brown hems, especially on the back and rump. On the underside of the body, some of the feathers are pure white. The arm wings and humeral feathers are dark brown, the hand wings are white with brown ends. In the first autumn-winter dress, the number of white feathers is significantly greater, especially on the underside of the body. On the head the white stripe appears as a clear brightening, the neck and throat are dark brown. In their first spring dress, young birds already have a completely white belly. The white spot on the sides of the head and in the neck becomes more contrasting.
In their second autumn-winter dress, juveniles are already largely similar to adult birds. Mainly on the upper side of the body there are still individual feathers from the previous dress. The wings of the hand are white with only narrow brown ends. The crimson crown is smaller than that of adult birds.
distribution
The red-crowned crane is at home in East Asia , especially in the Dongbei and Hokkaidō. On the Asian mainland, the Red Crane breeds almost exclusively in the catchment area of the Amur . Its distribution area extends from Lake Hulun in Inner Mongolia and the Jilin Province to the east across Heilongjiang to Lake Chanka and the Ussuri . The center of its distribution area is Heilongjiang, especially the area around the Songhua Jiang and the large Zhalong swamps near the city of Qiqihar . At the middle reaches of the Amur, where this river has large floodplains, the red-crowned crane shares the breeding area with the white-naped crane .
For the population on Hokkaidō it was assumed until the 1970s that it was a predominantly wintering population there. It was not until the ornithologist George Archibald found out that red-crowned cranes breed in the inaccessible Kushiro swamps. In the spring of 1972, an aerial survey of the Hokkaidō swamps counted no fewer than 53 nests. It is now known that the Hokkaidō cranes separated themselves from the mainland population within the Red-crowned cranes thousands of years ago. The different double calls indicate this. At the beginning of the 2000s there were about 160 breeding pairs on Hokkaidō. 53 breeding pairs have their breeding grounds in the 260 square kilometer marshland in the heart of the Kushiro Crane Sanctuary. Another large group breeds in the Akkeshi lagoon and in the coastal area of Nemuro .
The Red-crowned crane shows no pronounced migratory movements. The birds that breed in the Amurs region and the Zhalong Reserve migrate to the coastal regions north of Shanghai . The populations of Ussuri and Lake Chanka overwinter on the Korean peninsula. The population on Hokkaidō are resident birds.
habitat
The red-crowned crane prefers freshwater wetlands, swamps, and other humid habitats. As a particularly aquatic-oriented species, it lives mainly in high reed belts and in deep swamps. The main biotopes during the breeding season are wide sedge-cottongrass swamps and swampy sedge-calamagrostis meadows, which are relatively open and allow a wide panoramic view. It is characteristic of these biotopes that they are flooded every year in spring and then often have a water depth of 30 to 40 centimeters. In the middle of the summer they then become very dry.
In the catchment area of the Amur, the red-crowned crane is the first crane species to arrive here. It defines its breeding area - as far as possible - far away from human activities in the swamps. The white-naped crane, on the other hand, tends to stay in the edge areas of the same breeding habitat and also nests in reeds and in moist meadows near agricultural land.
food
The red-crowned crane has a very wide range of food. He primarily eats animal food. Only in the wintering areas and during certain periods does vegetable food represent the largest part of his food intake. The spectrum of animal food includes insects, worms, mollusks, fish, amphibians, birds and their eggs as well as small rodents. Rice and millet grains are eaten as vegetable food. Cranes in search of food walk slowly with their heads bowed and always stay longer in one place. They then grab their prey with a quick beak.
Reproduction
Red-crowned cranes reach sexual maturity between three and four years of age. They are monogamous birds, the pair bond is permanent. They return to their breeding grounds at a time when the earth has not yet thawed and there are regular frosts and snowstorms. As a rule, they start building their nests in the second half of April.
The size of a single breeding area is between 4.2 and 12.3 square kilometers. The distance between neighboring nests is between 2.7 and 4 kilometers.
Courtship dance
The mating dance of the red-crowned cranes is one of the most complex of the cranes. It is preferably performed in the wintering areas and both adult and young, not yet sexually mature birds take part in the "dances". The dances usually take place after eating. One of the birds begins to jump with its wings outstretched, the behavior jumps to other birds and soon there is a collective dance that engulfs the whole flock. As with most crane species, the courtship dances are polyfunctional. The courtship dance strengthens the pair bond, the bond between parent birds and teenage boys, and breaks down aggressive moods within the crane flock.
Dancing red-crowned cranes, like most species of Grus, rise on their toes, spread their coverts on their backs and spread their wings in what is known as a "butterfly pose". This makes the appearance larger and more impressive. In contrast to the other crane species, the dance of the red-crowned crane continues by lifting the outstretched wings high over the back and curving the neck so that the red crown comes to rest in front of the black umbrella feathers. The long, sharp beak points to the sky.
nest
The red-crowned crane builds its nest in relatively deep water in the middle of reeds . The water depth at the nest is usually between 10 and 50 centimeters. The nest consists of grass , reeds and other parts of plants. It is a flat oval platform that is about three to four feet long and about four to four feet wide. The thickness of the base varies between 5 and 20 centimeters. The actual nest trough is small at 35 × 50 centimeters in relation to the size of the platform.
The female lays two eggs, the interval between laying the eggs is two to four days. The eggs of the red-crowned crane are very smooth. The variable coloring of the eggshell is unusual. Red-crowned cranes occasionally lay pure white eggs, as occurs in the subtropical crane species. It is therefore assumed that the red-crowned crane originally also breeded in regions further south of East Asia, as the white shell usually has the function of reflecting the heat of the sun. The remaining eggs are sometimes bluish or spotted, as is the case with most northern crane species.
The incubation begins with the first egg and both parent birds are involved in the incubation. During the night the female usually sits on the nest, during the day it is replaced by the male two to three times. The replacement takes place in silence. The parent bird that has replaced it comes to the nest, the one that is just brooding stands up, cleans itself, occasionally turns the eggs again and then leaves the nest area. The incubation period is between 29 and 31 days. The brooding bird secures regularly by lifting its head up quickly. He also gets up regularly to turn the eggs. In total, the eggs are turned at least 20 times a day. Most often this happens during the noon and evening hours.
Wild red-crowned cranes leave their nest when a human comes within 200 meters. The bird that has been brooding up to that point stands up, then moves away 10 to 30 meters, flies up and lands again at a distance of about 600 to 800 meters. He then walks slowly in a circle around the nest area with wings hanging slightly.
Rearing the young birds
The hatching of the young falls mainly in the second decade of May to the first decade of June. There is no nestling competition between the two young birds and both young usually survive. The chicks are precocial and follow shortly after hatching the adult birds. In the first days of life, the downy cubs are huddled by one of the parent birds. When alarmed, the parent birds lead their young into deeper sections of the swamp. If the swamps dry out over the course of the summer months, the birds move to more humid areas.
The young grow up very quickly with a growth peak between the 10th and 40th day of life. They fledge after around three months and reach sexual maturity at three to four years of age. Unlike many other crane species, red-crowned cranes often raise both chicks.
Existence and endangerment
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The Red Crane population has declined sharply. The IUCN estimates the total population at around 2,400 animals and classifies the species as "critically endangered".
The main danger for the crane is anthropogenic influences, which lead to a loss of habitats for this crane species. The draining of wetlands, cattle drive, hay mowing, the application of chemical substances in the soil and water and thus impairment of the nutritional basis have led to the destruction of breeding grounds in large parts of its area of distribution. The worrying of the breeding cranes also has very negative consequences. They then leave their breeding grounds and the exposed clutches are then exposed to the risk of destruction by crows.
The protection of the red-crowned crane is sometimes very conflictual. At Lake Chankasee, the shore region of which lies both in China and in Siberia, the shore area is considered to be economically valuable agricultural land. On the Siberian side, it is even the most fertile soil, in which for a long time the only rice in the USSR and also cereals, soybeans and tomatoes could be grown. On the Chinese side, too, the area represents valuable arable land. In the Zhalong nature reserve , the red-crowned crane, who prefers a patchwork of reed islands and free water, could benefit from the fact that the population living in the neighboring area could only remove up to half of the reeds. For these people, however, the reed harvest accounts for between 70 and 80 percent of their income. The inhabitants are therefore forced to harvest more reeds than is compatible with protecting the birds.
Conservation measures
Red-crowned cranes are reared in a number of zoos and reserves. After all, the captive population is so large that there is no global stud book, but regional stud books, mostly related to the respective continent. In Japan, experience has shown that flightless males lure females into their enclosures and raise offspring with them, which join the wild flocks of cranes as soon as they are able to fly.
In the Zhalong nature reserve, red-crowned cranes were raised by hand and released into the marshes . They were recaptured during the winter months to prevent losses over the winter. In the years that followed, these birds mated either with each other or with wild red-crowned cranes and raised offspring not far from where they were raised. He, too, was kept in captivity with his parents during the first half of the winter. These semi-wild cranes tolerate the presence of humans to a greater extent than their wild counterparts, which is the aim of this measure.
Cultural meaning
The red-crowned crane is considered to be the most common type of crane depicted in East Asian art. The Chinese philosophers saw the black pattern that appears when the red-crowned crane spreads its wings as a manifestation of the yin and yang principle . Images can be found embroidered on kimonos, reproduced as woodcuts, painted on screens and drawn on scrolls. For the Ainu , the indigenous people of Japan, the red-crowned crane is both a messenger of death and a symbol of eternal life. The cranes were also hunted in Japan, although the hunt, which was carried out with falcons, was reserved for the Japanese high nobility for a long time. Only after 1867, the year of the Meiji Restoration , was it allowed in Japan that the rural population was also allowed to hunt cranes. The custom developed to eat cranes at New Year. As early as 1889, the population was so depleted that it was believed that the red-crowned crane had largely been exterminated in Japan.
At the beginning of the 20th century the red-crowned cranes had also disappeared on Hokkaidō. In 1910, red-crowned cranes were spotted again, and in 1924 a small flock was observed in the Kushiro swamps for the first time. The crane hunt was then banned and the Japanese Ministry of Culture declared the Manchurean crane a national monument. As early as the 1930s, 2,700 hectares in these swamps were designated as a special retreat. During a severe frost spell in 1952, local farmers rescued a remaining flock of 30 red-crowned cranes who had gathered around a hot spring by laying grain. This tradition continues to this day.
literature
- David H. Ellis , George F. Gee , Claire M. Mirande (Eds.): Cranes: Their Biology, Husbandry, and Conversation , Hancock House Publishers, Blaine 1996, ISBN 0-88839-385-7
- Peter Matthiessen : The Kings of the Skies - Traveling with Cranes , Fischer Taschenbuch Verlag, Frankfurt am Main 2010, ISBN 978-3-596-18195-7
- RL Potapov, VE Flint (ed.): Handbook of the birds of the Soviet Union. Volume 4: Galliformes, Gruiformes. Aula Verlag, Wiesbaden 1989, ISBN 3-89104-417-8
Web links
- Photos of the red-crowned crane
- Grus japonensis in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed January 31 of 2009.
- Videos, photos and sound recordings of Grus japonensis in the Internet Bird Collection
Individual evidence
- ↑ Ellis et al., P. 285
- ↑ Matthiessen, p. 23
- ↑ Matthiessen, p. 216 and p. 232
- ^ Potapov & Flint, 1989, p. 216
- ↑ a b c Potapov & Flint, 1989, p. 215
- ↑ Matthiessen, p. 20 and p. 21
- ↑ Matthiessen, p. 201
- ↑ Matthiessen, p. 205
- ↑ Matthiessen, p. 217 and p. 222
- ↑ Matthiessen, p. 44
- ↑ a b c d Potapov & Flint, 1989, p. 218
- ^ Potapov & Flint, 1989, p. 221
- ↑ Matthiessen, p. 206 and p. 207
- ↑ a b Matthiessen, p. 45
- ↑ a b c Potapov & Flint, 1989, p. 219
- ^ Potapov & Flint, 1989, p. 218 and p. 219
- ↑ Ellis et al., P. 82
- ↑ Matthiessen, p. 51
- ↑ Matthiessen, p. 180
- ↑ Ellis et al., P. 179
- ↑ Ellis et al., P. 233
- ↑ Matthiessen, p. 195 and p. 196
- ↑ Matthiessen, p. 217
- ↑ Matthiessen, p. 196
- ↑ Matthiessen, p. 197
- ↑ Matthiessen, p. 199