Mekong Wagtail

The Mekongstelze (Motacilla samveasnae ) is a Singvogelart from the family of Wagtail. It is in the northeast of Cambodia and southern Laos endemic, where it grows on rock and shrubbery interspersed whitewater sections in the catchment area of ​​the Mekong River. The black and white Stelzenart was described only in 2001 and is run due to its small distribution area and various planned dam projects in the Mekong region by the IUCN on the early warning ( " near threatened "). Subspecies are not described.

Description

The Mekongstelze strongly reminiscent of the African Witwenstelze, but is smaller with 17.0 to 17.5 cm body length. The beak is black with about 19 mm in length relatively longer. The wing length is between 80 and 87 mm, tail length 75.0 to 81.5 mm.

In adult males the top is mostly blackish brown to black. These contrasting white over a broad eye-streak, chin and throat, and a crescent-shaped patch on the sides of the neck. In contrast to the black Witwenstelze apex extends to the forehead and beak, the black breast band at the top edge down to the throat. The underside is white. The wings and the tail feathers are very similar to that of the Witwenstelze, the former is so predominantly brown black with white seams, the blackish tail shows white outer edges. The distinguishing features are low. Among others, the large coverts in most individuals dark spring centers. Only in some instances they act as completely white wing box.

Females usually show on the top of a rather brownish-black to brown -gray color. This contrasts strongly with the black reins, ear-coverts and the chest band. In the relatively bright, upper side gray-brown juvenile plumage the head and chest patterns are not as pronounced as in adult birds. Birds in first winter resemble - if known - the females, but show less white in the wing.

Voice

The Flugruf the Mekongstelze is a short, sharp Dzier, which will be carried forward ranked sometimes disyllabic or arousal. He is a little stilts typical and reminiscent of appropriate calls from beach or water pipit. More calls, which are mostly made ​​of seated birds, are short, thin and soft, such as tsiep or tsriu.

In singing, there are two types: a frequently heard, simple and a complex variant. Both appear to have both a meaning in the territorial defense and in courtship. The simple song consists of quick verses short, high tones that are carried forward by some distance. The complex variant consists of fast runs high tones, which also contain numerous elongated, sometimes humming sounds. It recalls the song of Erlenzeisigs.

Distribution and population

The Mekongstelze is in southern Laos and northeastern Cambodia endemic in the catchment area of ​​the lower Mekong River, where it also occurs in the tributaries Kong, Pian, and San Srepok. The wintering areas of the species are unknown. Outside the breeding season, only two specimens were found in December in Ubon Ratchathani province in northeast Thailand so far. The stock is estimated at less than 20,000 individuals. Since the species is not susceptible to human disturbances and the required habitats are not threatened directly, the stock is probably quite stable. Longer-term threats are the planning of numerous dams along the Mekong River, so that the IUCN is the type on the early warning list.

Habitat

The Mekongstelze breeds on broad rivers of the lowlands below 110 m, where in very fast flowing rocky areas, bush -lined islands and gravel bars are marked. The species avoids forests and is a rare guest on open waterfront areas such as sandbanks or alluvium on. During the floods in August and September, the habitats of Mekongstelze are usually completely under water. From this period there is only one observation of a bird sitting on a bush in the middle of outstanding high water masses. Unlike most Stilts the type will often have to search for food in the bushes, where she runs around on branches and food pecks.

System

Since the Mekongstelze of African Witwenstelze is very similar, it is possible that it is a subspecies of the latter kind. But vocal, environmental and heritage coated mouse features they differ very significantly from the two subspecies of Witwenstelze. Add to this the fact that the range of the Mekongstelze from the Witwenstelze is far away. Studies of mitochondrial DNA also indicate that the Mekongstelze is more closely related to all other black and white stilt species, as with the subspecies M. a vidua the Witwenstelze. THe M. nominate a aguimp but lacked in the investigation.