Wilsonbekassin
| Wilsonbekassin | ||||||||||
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Wilsonbe Cassin ( Gallinago delicata ) |
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| Systematics | ||||||||||
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| Scientific name | ||||||||||
| Gallinago delicata | ||||||||||
| ( Ord , 1825) |
The Wilsonbekassin ( Gallinago delicata ) is a medium-sized, long-beaked bird species from the family of the snipe birds (Scolopacidae). It populates large parts of North America from the northern United States northwards across Canada and Alaska to the tundra zone . Until 2002 it was regarded as a subspecies of the Palearctic common snipe . Due to various characteristics, it is now given species status.
description
The Wilsonbekassine is very similar to the common snipe. The body length is about 28 cm, with just under 6 cm on the beak. The weight is around 100 g. The iris is dark brown, the legs and feet are greenish yellow or blue-gray in color with dark brown claws. The tip of the beak is dark brown, and the base is matt red-brown. The sexes do not differ. The species is monotypical . A geographical variation is not described.
The dark dashed head on a beige background shows the typical stripe pattern of the genus. The parting is dark, the stripe above the eyes is light. A dark eye stripe extends down to the nape of the neck and another dark vertical stripe appears on the ear covers. The plumage on the upper side appears predominantly dark brown, with the dark feather centers being provided with a reddish-brown, slightly concentric streaked to blotchy pattern. Four light longitudinal bands stand out from this, which are formed by the yellowish beige outer hems of the shoulder feathers. The upper tail-coverts are banded dark on a beige-brown background. The tail shows a reddish brown band in the distal quarter and a whitish end border on a dark background. In contrast to the snipe, it consists of 16 control springs , i.e. one pair more on average. The upper wing is predominantly dark brown with a whitish rear edge, which is somewhat narrower than that of the common snipe. In addition, the end seams of the large arm covers and the inner hand covers form a narrow, whitish wing band. The middle arm covers are broadly lined with yellowish beige with rust-brown markings on the dark centers. The under wing-coverts are banded dark brown on a whitish background and, in contrast to the common snipe, have no larger, white areas. The breast has a finely dark pattern on a whitish-beige background, the rest of the underside is more whitish, with a coarse dark brown banding over the lower breast and flanks, but the lower abdomen is pure white.
Vocalizations
Like most species of the genus, the Wilsonbe cassin marks its territory during the breeding season by circling expressive flights. With these, it can be repeatedly dropped from great heights at steep angles and, with the spreading, outer control springs, creates a humming noise in the airflow, which is modulated by vibrating wing beats. The resulting, somewhat owl-like huhuhuhuhu (audio sample) is faster and higher than the "thump" of the Eurasian snipe. It is particularly reminiscent of the singing of the Eastern Screech School .
Also, mostly during the breeding season, a chip-per chip-per (audio sample) can be heard, often over long periods of time and from a control room . A hard chik is used as a cry of excitement .
If a Wilson kassin is frightened on the ground, it gives a hoarse ääätsch (audio sample) and, after a typical, steeply ascending zigzag flight , falls back into cover after some distance . This call can also be heard during pursuit flights and as a night train call.
distribution
The distribution area of the Wilsonbekassine extends over large parts of the temperate zone of the Nearctic .
It extends from the central Aleutian Islands in the west across Alaska through Canada to Newfoundland . The northern limit of distribution runs roughly along the tundra border through the northern Yukon , the northern center of Mackenzie , the north of Manitoba and Ontario and the northwest of Québec . On the Pacific coast south of Alaska the closed distribution begins east of the cascade chain , west of it there are only scattered occurrences - for example on Haida Gwaii , in the east of Vancouver Island , in the lowlands of the Fraser River , on the Puget Sound and in the Willamette Valley . In the south, the area extends to Inyo County in California , to western and northern Nevada , to central Utah , to the extreme north of New Mexico , northwestern Nebraska and through South Dakota . In the eastern part of North America, the distribution extends south through western Iowa , a little south along the Great Lakes and on the east coast through the middle of the New England states . To the south of this distribution limit there are only a few, very scattered breeding occurrences.
habitat
The Wilsonbe cassin breeds in habitats in which small open areas alternate with wet, humus-rich soil for foraging and dense vegetation with sufficient cover. However, the vegetation should not be too high and should provide a sufficient overview so that approaching predators can be recognized at an early stage. It meets these requirements in sedge beds , fens , on the edge of willow and alder swamps and on swampy banks of various inland waters.
On the train, the Wilsonbekassine can be found in swamps and moors, in wet grassland, on pastures and fallow land as well as on swampy banks. In the southern United States, it is common locally in rice fields and extensively used sugar cane plantations.
nutrition
The Wilsonbe cassin feeds mainly on insects in the larval stage , but also on small crustaceans , little bristles and mollusks . Stomach contents can contain up to 66% plant parts, but these are hardly broken down during digestion. They leave the intestine almost undigested. Small pebbles are picked up to aid digestion.
The food is searched for with the beak probing in wet, partly covered with shallow water, organic soil substance . The head is often sunk up to the eyes, sometimes completely in the water. Prey animals can be swallowed without their beak being pulled out of the ground. They are moved upwards in the beak with the help of the tongue. This is very flexible in the front part, so that it can be opened even when the beak base is closed. It is often pushed into the ground in the same place several times or a very small area is searched accurately. Prey animals are sometimes roused with trampling foot movements.
Reproduction
Young Wilsonbekassins reach sexual maturity towards the end of the first year of life. First broods of annual birds usually take place quite late in the breeding season. There is probably only one annual brood. Second broods have not yet been documented. Late clutches are either secondary clutches or clutches of annual birds that are breeding for the first time.
In the south of the range, the Wilsonbe cassin arrives in the breeding areas in early March, from southern Canada to southern Alaska in late April and in northern Alaska in late May. Males arrive 10-14 days before the females and occupy a territory that is defended by expressive flights. Initially, the female is courted by several males and mated by some. A firm pair bond arises only when the female, accompanied by the male, has chosen a nesting site and laid the first eggs.
The nest is usually on a Bulten built or at the bottom edge of very wet places and is well hidden in the vegetation. It is not infrequently surrounded by water. It is less common to find it in the grass in dry locations. In one case, a nest stood 50 cm high in the top of a bush.
The nest consists of a hollow that is lined with grass. In contrast to the nest of many other wading bird species, it is built relatively carefully and consists of an outer layer of interwoven, coarser stalks and a finer lining. Many nests retain their shape when picked up. The inside diameter of the trough is about 12.5 cm, the depth 3.5 cm.
The clutch usually consists of four, much less often three or two eggs. These are on average about 39 × 28 mm, round-oval and shiny. The basic color is either a dark or a light olive brown. There are dark spots or blobs on it that are brown or black and condense at the wider end. They are laid about 24 hours apart and only incubated when the last one is laid. The incubation period is 18–20 days.
It incubates and hudert almost exclusively the female. The male only covers the eggs when the female takes short breaks to leave the clutch to forage.
The young usually hatch within 5–6 hours. As soon as their downy clothes are dry, they become restless, climb onto the back of the female or leave the nest to explore the area. If the female is still brooding or rowing, she stands up briefly and guides the chicks back to the nest.
The parents share the rearing of the young, whereby both males and females usually have two young each. They usually move away from each other and no longer come into contact with each other. The young are taken to suitable places to eat, huddled for a few days and sometimes fed for several weeks. Presumably they are independent after about 19-20 days. From the age of six weeks, they join together with other young birds and form larger groups of sometimes more than 100 individuals in places rich in food.
Duration
The number of Wilson snipe was reduced towards the end of the 19th century through mostly sporty hunting and later decreased again due to the loss of habitat caused by civilization , albeit never to a threatening extent. This bird has only rarely been hunted for years and is still quite present in its ancestral home.
literature
- Helmut Mueller: Wilson's Snipe (Gallinago delicata) , in A. Poole (Ed.): The Birds of North America Online , Cornell Lab of Ornithology, Ithaca 1999 doi : 10.2173 / bna.417
- Peter Hayman, John Marchant, Tony Prater: Shorebirds: An identification guide. , Houghton Mifflin Company , Boston 1986, ISBN 0-395-37903-2 .
- A. Bezener: Birds of Ontario , Edmonton: Lone Pine publishing, p. 149 (2000)
Individual evidence
- ^ Richard C. Banks, Carla Cicero, Jon L. Dunn, Andrew W. Kratter, Pamela C. Rasmussen, J. v. Remsen Jr., James D. Rising, Douglas F. Stotz: Forty-third supplement to the American Ornithologists' Union Checklist of North American Birds , The Auk , 119/3, 2002, pp. 897-906
- ↑ a b H. Mueller (1999), sections Distinguishing Characteristics and Appearance
- ^ H. Mueller (1999), section Systematics
- ↑ Prater et al. (1986), pp. 170 and 354f
- ↑ Andrew Spencer: XC14873 Wilsonbekassine Gallinago delicata (MP3) xeno-canto.org. June 14, 2007. Retrieved September 14, 2019.
- ↑ a b H. Mueller (1999), section Sounds , see literature
- ↑ Chris Parrish: XC21809 Wilsonbekassine Gallinago delicata (MP3) xeno-canto.org. June 8, 2008. Retrieved September 14, 2019.
- ↑ Robin Carter: XC11712 Wilsonbekassine Gallinago delicata (MP3) xeno-canto.org. March 27, 2007. Retrieved September 14, 2019.
- ↑ a b H. Mueller (1999), section Distribution , see literature
- ↑ a b H. Mueller (1999), section Habitat , see literature
- ↑ a b H. Mueller (1999), section Food Habits , see literature
- ↑ a b c d e f g h H. Mueller (1999), section Breeding , see literature
- ↑ H. Mueller (1999), section Demography and Populations , see literature
