Mekong wagtail

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Mekong wagtail
Motacilla samveasnae, Cambodia 1.jpg

Mekong wagtail ( Motacilla samveasnae )

Systematics
Order : Passerines (Passeriformes)
Subordination : Songbirds (passeri)
Superfamily : Passeroidea
Family : Stilts and pipiters (Motacillidae)
Genre : Stilts ( Motacilla )
Type : Mekong wagtail
Scientific name
Motacilla samveasnae
Duckworth, Alström , Davidson, Evans, Poole, Setha & Timmins, 2001

The Mekong wagtail ( Motacilla samveasnae ) is a songbird species from the family of stilts and pipiters . It is in the northeast of Cambodia and southern Laos endemic , where she attended rock and bushes interspersed white-water sections in the catchment area of the Mekong occurs. The black and white stilt species was only described in 2001 and is on the IUCN's early warning list (“near threatened”) due to its small distribution area and various planned dam projects in the Mekong region . Subspecies are not described.

description

The Mekong wagtail is very reminiscent of the African widow wagtail , but is smaller with a body length of 17.0–17.5 cm. The black beak is relatively longer at around 19 mm in length. The wing length is between 80 and 87 mm, the tail length between 75.0 and 81.5 mm.

In the adult male, the upper side is predominantly blackish to black-brown. There is also a contrasting white stripe above the eyes , chin and throat, and a crescent-shaped spot on the sides of the neck. In contrast to the widow's wagtail, the black crown extends to the forehead and beak, the black chest band on the upper edge extends to the throat. The underside is white. The wing and tail plumage are very similar to that of the widow wagtail, so the former is predominantly brown-black with white edges, the blackish tail shows white outer edges. The distinguishing features are few. Among other things, the large arm covers show dark feather centers in most individuals. Only in some specimens do they appear as a completely white wing field.

Females usually show a brown-black to brown-gray color on the upper side. This contrasts strongly with the black reins, ear covers and the chest band. In the relatively light, gray-brown on the top, the head and breast patterns are not as clearly pronounced as in adult birds. Birds in the first winter resemble - as far as known - the females, but show less white in the wing.

voice

The flight call of the Mekong wagtail is a short, sharp dzier , which is sometimes presented in two syllables or in a row when excited . It is not very typical of stilts and is more reminiscent of the corresponding calls from beach or water pipit . Other calls that are mostly made by sitting birds are short, thin and soft, such as tsiep or tsriu .

There are two types of singing: a common, simple and a more complex variant. Both apparently have a meaning both in the defense of the territory and in courtship. The simple singing consists of quick stanzas of short, high notes, which are performed with some distance. The more complex variant consists of fast runs of high notes, which also contain numerous drawn out, sometimes humming sounds. It is reminiscent of the singing of the siskin .

Distribution and existence

The Mekong wagtail is endemic in the catchment area of ​​the lower Mekong in southern Laos and northeast Cambodia, where it also occurs in the Kong, Pian, San and Srepok tributaries. The wintering areas of the species are unknown. Outside the breeding season, only two specimens have so far been found in December in the province of Ubon Ratchathani in northeastern Thailand . The population is estimated to be less than 20,000 individuals. Since the species is not susceptible to human disturbance and the required habitats are not directly threatened, the population is probably quite stable. Long-term threats lie in the planning of numerous dam projects along the Mekong, so that the IUCN is putting the species on the warning list.

habitat

The Mekong wagtail breeds on broad rivers of the lowlands below 110 m height, where rocky, bushy islands and gravel banks are pronounced in very fast-flowing areas. The species avoids forest areas and rarely stays on open bank areas such as sandbanks or alluvial land. During the floods in August and September, the habitats of the Mekong wagtail are mostly completely under water. From this period there is only one observation of a bird sitting on a protruding bush in the middle of the flood masses. Unlike most stilts, the species is often found looking for food in the bushes, where it walks around on branches and picks up food.

Systematics

Since the Mekong wagtail is very similar to the African widow wagtail, it is possible that it is a subspecies of the latter species. Vocal, ecological and moulting characteristics distinguish them very clearly from the two subspecies of the widow wagtail. In addition, the range of the Mekong wagtail is far removed from that of the widow wagtail. Investigations of the mitochondrial DNA also indicate that the Mekong wagtail is more closely related to all other black and white stilt species than to the subspecies M. a. vidua of the widow wagtail. The nominate form M. a. aguimp was not included in the investigation.

literature

  • Per Alström, Krister Mild: Pipits and Wagtails of Europe, Asia and North America , Christopher Helm, London 2003, ISBN 0-7136-5834-7

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