Friday, December 25, 2009

Yellow Wagtail/Gul Vipstjert

Motacilla flava

The Yellow Wagtail is a small passerine in the wagtail family Motacillidae, which also includes the pipits and longclaws.This species breeds in much of temperate Europe and Asia and has a foothold in North America in Alaska. It is resident in the milder parts of its range, such as western Europe, but northern and eastern populations migrate to Africa and southern Asia.
Yellow wagtail is like the other wagtails characterized byt its long tail, which gave the bird its name. There are various species with very varied looks, but what is shared is the male bird's yellow belly and olive back, the belly of the female birds is light yellow. The head pattern of the male is various in various species. The most common wagtail in Denmark is yellow wagtail (M.flava) with a blue-grey head with a clear white eye and beard-stripe. The male of northern yellow wagtail (M.thunbergi) which is a common migrating bird in Denmark, lacks the white eyestripe, and the head is darker than the common yellow wagtail. The male of yellow-headed yellow wagtail (M. flavissima) which is sporadicly seen in West Jutland, has an olive head with a yellow eye stripe. Neighbouring wagtails differ most, maybe because the female bird prefers the male of their own species with the clearest features - pairs of the same species have a better breeding succes than mixed pairs.
In Denmark the wagtail mostly breeds in meadows with a low grass growth, mainly along the coast and at fjorde with beach meadows. It also breeds in inland moors. The largest population in Denmark is at the birds' sanctuaries Vejlerne and Tipperne in North Jutland and at coast areas near Copenhagen and along the bay of Køge. The Danish breeding birds mainly belong to common Yellow Wagtail.
In migrations time the northern Yellow Wagtail is a common guest in Denmark. It is seen at the migration areas or resting at meadows and large grass areas, i.e. golf courses all over the country. The European wagtails overwinter in tropical Africa, while the East Asian wagtails overwinter i India and South East Asia.
The yellow wagtail's food is insects which it catches upon the ground or in the air. Lesser flocks can hunt mosquitoes in the morning- and evening hours above waters, while they in the day hours separately hunt manure flies which gets easily started from cow pats. The long tail supports the balance when the bird catches insects in the air or while running on the ground.
The yellow wagtail has declined as a breeding bird in Denmark during the last decades. This is due to that its preferred habitat, grazed moist areas have decreased either by draining, cultivating or overgrowth.
Dansk Ornitologisk Forening

Photo Margrethekog, Vadehavet : grethe bachmann

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