Sandhill crane
| Sandhill crane | ||||||||||||
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Sandhill cranes ( Grus canadensis ) with the rust-red tinge of plumage typical of the moulting season |
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| Scientific name | ||||||||||||
| Grus canadensis | ||||||||||||
| ( Linnaeus , 1758) |
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The sandhill crane ( Grus canadensis , Syn. : Antigone canadensis ), which derived from the English term " Sandhill Crane " sometimes as sandhill crane is called, is a bird art from the family of the Gruiformes . It occurs in North America and in the extreme northeast of Asia. The sandhill crane is evenly colored gray-brown. Adult birds have a red section on the forehead, white cheeks and a long, pointed beak.
The population is estimated at 650,000 animals worldwide. While the subspecies Little Sandhill Crane ( Gc canadensis ) and Common Sandhill Crane ( G. c. Rowani ) are not considered threatened, the population of the Mississippi Cranes ( G. c. Pulla ) has declined sharply due to the pollution of the river. Only 120 to 300 adult birds are counted from this subspecies.
Appearance
Adult birds
There is no gender dimorphism . The body length ranges from 88 to 120 centimeters, the actual body length is forty to fifty centimeters. The females are usually slightly smaller than the males. Their wingspan is between 160 and 210 centimeters. They reach a weight of 3–6 kg. The iris is orange to brown-orange, the beak is brown. The legs and feet are dark gray.
The forehead and top of the sandhill crane are not feathered, but have only sparse and short hair-like bristles. The chin and throat are white, the rest of the plumage is smoky gray, the top of the body being slightly darker than the underside of the body. Worn plumage is often brown in color. During the moulting season, the plumage is colored by the iron oxides contained in the water , so that the dorsal plumage has a rust-red tinge.
Fledglings
Newly hatched dune young are maroon on the top of the head, the back neck, the back and the wings. The top of the body, the chest and the front of the neck are significantly lighter and have a reddish tinge. The belly and throat turn gray-whitish. The second dune dress is similar to the first, but less contrasting overall.
When young, the young birds initially have a reddish head and neck. The top of the body is reddish yellow-gray and the underside of the body is dirty gray. In their first autumn-winter dress, fledglings have a gray neck and head. At this point the head is still completely feathered. The bare forehead and parting that is characteristic of adult sandhill cranes appear in juveniles for the first time when they wear their first spring dress. Young birds are now largely similar to adult birds, but they still have individual reddish feathers. In the second autumn dress, the bare skin area on the forehead and crown is fully developed.
Locomotion
Soaring sandhill cranes have to walk a few steps on the ground before they can rise into the air. Like other crane species, they fly in a straight line with powerful, wide flaps of their wings. Flying flocks of cranes often form a wedge.
Sandhill cranes move on the ground with long, calm strides. They are also able to swim.
voice
Sandhill cranes call very loudly and persistently. Her trumpet-like scream is reminiscent of a guttural "R". Due to their constant calling, they can be easily distinguished from herons even in flight.
As with other crane species, the common duet with the partner bird is characteristic of the sandhill crane. The two birds stand in parallel at a distance of two to three meters from each other. The duet begins with the male. When calling, the wings of the male are laid out, the neck is stretched upwards and slightly backwards. The beak points upwards. The female also has her neck stretched upwards, but keeps her beak in a horizontal position. It calls until the male is silent.
The joint duets of the two partner birds have multiple functions. They are carried out both in the breeding area and in the wintering area, but have their main function as a territorial signal.
distribution
The sandhill crane is the most common type of crane. The breeding areas of the sandhill cranes are in the marshland and marshland as well as the savannas and prairies of central and northern Canada , in Alaska , in some parts of the Midwest and south-east of the USA and in northeast Asia. The main breeding area of the species is in North America. In northeast Asia, the breeding area extends from Uelen to the lowlands of Kolyma and Alaseja in the west and to the Kamchatka Narrow and the lowlands of the Penshina River in the southeast.
habitat
In Asia, the Canada Empire populates a broad spectrum of biotopes typical of flat and hilly tundras. These include moss-grass lowlands on lakes with cotton-grass bulbs, slopes and foothills of low peaks in the mountain tundra, swampy moss-sedge-shrub-hill tundra, subarctic moss-sedge-dwarf shrub-shrub areas with low willows, crowberry, porch, dark berries and alder bushes , the bottoms of mountain valleys and plains surrounding the estuaries of large rivers and hills. In Asia they rarely use regions that are at altitudes over 500 meters, slopes that are more than 25–30 ° and plains that are flooded in spring.
hikes
Of the six subspecies, three are migratory birds. The Little Sandhill Crane breeds in the arctic and subarctic regions of northern Canada, Alaska, and northeast Asia. It winters in the American Southwest and northern Mexico.
The withdrawal from the breeding grounds in Asia begins at the end of June. The time of the spring migration depends on the weather. In years with early spring, sandhill cranes appear again in their Asian breeding areas in the first days of May. In principle, the spring migration is more concentrated than the autumn migration, so that the troops observable in autumn are significantly smaller.
The birds living in the northeast have to cover a distance of up to 8,000 kilometers on their migration. The train follows the coast of the Pacific Ocean west of the Rocky Mountains. The sandhill crane is therefore the species with the longest migration distance within the crane bird family .
The cranes that breed in Asia cross the Bering Strait from the Seward Peninsula in spring. You move south of the Rotmanow Island and reach the Asian continent south of the Lavrentiabucht and then cross the Metschigmenbucht and the Metschigmenenge. When they reach Bering Bay, they fly at an altitude of 2000 to 2400 meters and at a speed of 60 to 65 km / h. The train front is 10 to 12 kilometers wide above the sea and fans out to 30 to 40 kilometers upon arrival at the coast. Behind the Metschigmen Plain, the sandhill cranes rest for several days on the tundra of the Erguwo-Nun-jamo inter-river land. During a period of five to seven days, therefore, significant accumulations of this kind form here. The accumulation dissolves as they continue to fly along the large valleys to their breeding grounds. The closer they get to the breeding grounds, the smaller the migrating crane flock becomes.
The wintering sites of the Great Sandhill Crane and the Common Sandhill Crane include California , New Mexico , Mexico, and Texas . The Platte River in Nebraska is one of the most famous stopovers on the train to their wintering grounds. Around 450,000 sandhill cranes gather there in spring and autumn. In their wintering areas, the crane flocks usually gather to spend the night on wide flat water areas with a muddy or sandy bottom. When daylight comes they set out from there to look for food in fields and swamp meadows.
food
Sandhill cranes feed on a wide variety of insects, aquatic plants, invertebrates and rodents, as well as seeds and berries. However, their diet is predominantly vegetable. For example, on the Chukchi Peninsula, summer food consists mainly of crowberry berries . The sandhill cranes also eat molteberries and lingonberries . This food is supplemented by insects and rodents. In Alaska and northern Canada, sandhill cranes eat not only various types of berries, but also fish, mollusks and flying insects. They also eat the eggs and young of snow geese and ptarmigan .
Wintering sandhill cranes feed primarily on wheat, barley, and corn kernels that they find in harvested fields. They also eat animal food in the form of rodents, fish, reptiles, frogs, insects and mollusks.
Reproduction
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Sandhill cranes reach sexual maturity between three and four years of age. They enter into a monogamous couple relationship, the relationship lasts over several reproductive periods.
nest
Sandhill cranes create their nests in wetlands in the riparian vegetation. The nesting site is usually a dry place. Even in very swampy moss-sedge tundras, the cranes build their nests on small elevations that are often surrounded by water. The nests are noticeably different in their construction. Birds that breed in the prairies and savannas often do not build nests, but lay their eggs on the bare ground. As a rule, however, the nests are a well-tamped pile of dry sedge and cotton-grass angels, which are usually mixed with various herbs and grasses and built into the branches of small shrubs and tufts of moss and lichen. In rare cases, the nests are very massive. They then consist of relatively thick branches of willow and dwarf birch, which are built with the help of dry moss and lichen bushes.
The nest is only used once. Sandhill cranes build a new nest every year.
The full clutch consists of two eggs. The eggshell is greenish or brownish to olive green with red-brown spots of different sizes, shapes and densities. Both parent birds breed. The incubation period is 29 to 30 days.
Rearing the young birds
In contrast to, for example, the black crane, there is a nestling competition. However, this does not necessarily lead to the death of one of the two young animals. The duel ends when the dominance of one of the two young birds is established. As a rule, however, only one young bird grows.
As soon as the young birds have left the nest, the family strays far into their breeding ground. At about a month and a half, the young birds are fully fledged and begin the migrations with their parents before the autumn migration.
Subspecies
Six subspecies are distinguished within the large distribution area:
- Little Sandhill Crane ( Gc canadensis )
- Sandhill crane ( Gc rowani )
- Great sandhill crane ( Gc tabida )
- Florida crane ( Gcpratensis )
- Mississippi crane ( Gcpulla )
- Cuban crane ( Gc nesiotes )
Others
To save the rare whooping cranes , attempts were made, among other things, to have their eggs hatched by sandhill cranes. This project failed, however, because whooping cranes hatched by sandhill cranes were shaped as sexual partners in this way.
supporting documents
literature
- Wolfgang Mewes, Günter Nowald, Hartwig Prange; Cranes - myths, research, facts , G. Braun Buchverlag Karlsruhe 1999, ISBN 3-7650-8195-7
- Richard Sale: A Complete Guide to Arctic Wildlife. Christopher Helm, London 2006, ISBN 0-7136-7039-8 .
- RL Potapov, VE Flint (HRSG): Handbook of Birds of the Soviet Union. Volume 4: Galliformes, Gruiformes. Aula Verlag, Wiesbaden 1989, ISBN 3-89104-417-8
Web links
- English-language website of the International Crane Foundation about the sandhill crane
- Antigone canadensis in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed January 30 of 2009.
- Videos, photos and sound recordings of Grus canadensis in the Internet Bird Collection
Single receipts
- ↑ Sale, p. 165
- ^ Potapov & Flint, 1989, p. 228
- ^ Potapov & Flint, 1989, p. 227
- ↑ a b c Potapov & Flint, 1989, p. 234
- ^ Potapov & Flint, 1989, p. 229
- ↑ Potapov & Flint, 1989, p. 230 and p. 231
- ↑ a b Potapov & Flint, 1989, p. 230
- ↑ a b c Potapov & Flint, 1989, p. 232
- ↑ a b Potapov & Flint, 1989, p. 231