Two forms of Yellow Wagtail Bird occur within our region, the 'Yellow' Wagtail M. flava flavissima, which breeds in Britain and in adjacent Europe, and the 'Blue-headed' Wagtail M. flava flava, which occurs across most of Europe. Both forms share many features, being rich yellow from chin to vent, with a long white-edged tail, green upperparts and wing feathers patterned with darker centres and pale fringes. The male flavissima has a greyish-green crown and eyestripe, the yellow of the underparts extending onto the face, supercilium and forehead, while the male flava has a blue-grey crown, cheek and nape, with a white supercilium. Females are paler, washed primrose-yellow below, whiter on the throat and with duller pale grey-brown heads.
Yellow Wagtail Bird is a summer visitor from Africa, it breeds in damp, grassy habitats and the margins of wetlands, such as saltmarshes, pastures, water meadows, marshes, lakes, riversides, fens, peat bogs and sewage farms, as well as in crops where wet or marshy areas occur nearby. It is often seen in close association with livestock, feeding around their feet on the insects that are disturbed. On migration it can be found in similar habitats, often on pastures, golf courses and other short-cropped grassy areas. The form M. flava flavissima has decreased considerably in Britain in recent years.
The typical call of Yellow Wagtail Bird, frequently given in flight, is a liquid, often plaintive "fsseep", "fsss'up", "wzeeer" or "wee'ssep", often with two components audible although not quite disyllabic, descending towards the end of the note. It also gives a single shorter "tseh" and an anxious Chaffinch-like "chiwaink". The song is very simple, an undeveloped couple of rasping buzzy notes such as "zeeri'ziip", "zeeer'p" or "wzzzeer-zeup", sometimes with a phrase of twittering notes, and delivered from the top of a large plant, fence post or bush, and sometimes in a song flight of languid undulations.