The American crane [1] [2] ( lat. Grus americana ) is a large bird , the rarest species from the family of true cranes , its number currently stands at only about 400 individuals. It lives in North America .
| Whooping Crane |
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| Scientific classification |
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| No rank : | Bilateral symmetrical |
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| International scientific name |
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Grus americana
( Linnaeus , 1758 ) |
| Area |
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| Security status |
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Endangered speciesIUCN 3.1 Endangered : 22692156 |
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Content
A large bird with a height of about 150 cm and a wingspan of 210-240 cm. Males are slightly larger than females, their weight averages 7.3 kg, while females have 6.4 kg. The plumage is completely snow-white, with the exception of the black endings of the first order feathers on the wings and the black mustache, diverging on both sides of the beak. The feather feathers of the third order are noticeably elongated and lower at the back in the form of a plume. There are no feathers on the top of the head, the skin in this place is dark red. The cornea is golden yellow. The beak is yellowish, sometimes at the end it has a dull green hue. The legs are black. Sexual dimorphism (visible differences between males and females) is not pronounced. Young cranes are noticeably different from adult birds - their body is completely covered with feathers, including the head. The plumage, with the exception of the wings of the wings, is white with numerous red spots, which gradually decrease with age and then disappear. The feathers of young birds are dark gray. The color of the eyes of the chicks is blue.
Currently, American cranes are on the verge of extinction, and their population is limited to a very small territory of North America. The remaining birds nest in the area of ββthe Wood Buffalo National Park in the Northwest Territories of Canada , where they were accidentally discovered in 1954 by a forest ranger and a helicopter pilot, and migrate on the Gulf of Mexico in winter in the Aransas Reserve in the US state of Texas .
However, numerous fossil finds suggest that American cranes were widespread in North America several million years ago during the Pleistocene , their range covered a vast territory from central Canada in the north to Mexico in the south and from Utah in the west to the Atlantic coast in the east . A sharp decrease in the number of American cranes occurred in the second half of the 19th century , which is associated with human economic activity and uncontrolled hunting. As a result, the number of birds decreased only to 10-12 pairs, which were discovered in 1954 in hard-to-reach areas.
With the exception of a small group of sedentary birds in southwestern Louisiana , nesting sites for cranes were crowded out of the United States at the end of the 19th century. The remaining Louisiana population completely disappeared by the middle of the 20th century: the last remaining birds were seized for cages in 1950.
Earlier, the American crane lived in a fairly wide range of different biotopes . Up to a sharp decline in the population, he nested mainly in prairies with tall grass in the north of the Midwest and aspen thickets in eastern Canada. However, its nests could be found in completely distinct taiga and subarctic Northwest territories of Canada, as well as on the swampy coast of the Gulf of Mexico in the southeastern United States. Although the common feature of the winter camps of all these ecosystems was the presence of wetlands, its character varied significantly from the marshes in the highlands of Mexico to the Atlantic coast of Texas and South Carolina . In addition, a rather large number of various routes to winter parking sites were observed in migrating populations.
American cranes are omnivorous - eat both plant and animal food. During the breeding season, their main diet consists of mollusks , crustaceans , insects , small freshwater fish , frogs and snakes . During winter migration, they feed on various conditions: on arable land sown with corn , wheat or sorghum ; in the middle of large and small swamps, along the shores of lakes and reservoirs, on riverbanks.
As with other types of cranes, the held couple celebrates its connection with a joint characteristic singing, which is a series of complex drawn out melodic sounds. During singing, the cranes occupy a vertical position, usually throw their head back so that the beak is directed vertically upwards. In American cranes, the female begins to sing, emitting two high sounds in response to each lonely lower sound of the male. In this case, the male spreads its wings while the female keeps them folded. During courtship, the cranes dance, which can result in bouncing, running, tossing tufts of grass or sticks and flapping wings. The nesting area can vary quite significantly and varies from 1.3 to 47.1 kmΒ². [3] [4]
The nest is built right in the water with a depth of 14β28 cm [3] [5] in shallow water, in the middle of small lakes or in flood meadows and is a well-packed pile of reeds , sedge or other marsh grass with a small indentation at the top. Around the nest there are always areas with water that are difficult to access for land predators. Egg laying occurs in May; the female usually lays 2 eggs (in less than 10% of cases 1 egg) 10.8 Γ 6 cm in size and weighs about 207 g with a break of 2-3 days. [6] The incubation period lasts 29-30 days. Both parents incubate, but the female spends most of the time in the nest. As a rule, only one chick survives before winter migration, as competition for survival begins between the two chicks, ending in the death of one of them. American cranes rise on the wing after 80-90 days. Puberty of young birds occurs in 4-5 years.
The main reasons for the sharp drop in the number of American cranes are called a decrease in the area of ββland suitable for these birds, as well as environmental pollution. In addition, among destructive factors are oil production near the Aransas reserve, violation of the natural fresh water circulation system, increased tourism, injuries from collisions with power lines, illegal hunting of these birds, bird tuberculosis and poor genetic biodiversity due to the small number of surviving birds.
Since the early 1970s, with the formation of the International Crane Protection Fund and subsequent rehabilitation programs, the situation has slowly begun to change for the better. In the Wisconsin Foundation Nursery, projects have been established to artificially breed these and other rare crane species and then introduce them into the wild. Currently, these programs are bearing fruit - the number of birds has increased to 400 individuals.
- β Boehme R. L. , Flint V. E. The Bilingual Dictionary of Animal Names. Birds. Latin, Russian, English, German, French / Ed. ed. Acad. V. E. Sokolova . - M .: Rus. lang., "RUSSO", 1994. - S. 68. - 2030 copies. - ISBN 5-200-00643-0 .
- β Fisher D., Simon N., Vincent D. Red Book. Wildlife at risk / trans. from English, ed. A. G. Bannikova . - M .: Progress, 1976. - S. 296-299. - 478 p.
- β 1 2 Kuyt, E. 1981. Population status, nest site fidelity, and breeding habitat of Whooping Cranes. Crane Research Around the World: 119-125.
- β Kuyt, E. 1993. Whooping Crane, Grus americana, home range and breeding range expansion in Wood Buffalo National Park, 1970-1991. Can. Field-nat. 107: 1-12.
- β Kuyt, E. 1995. The nest and eggs of the Whooping Crane, Grus americana. Can. Field-nat. 109: 1-5.
- β Searchable Ornithological Research Archive
