A slender, active bird with a constantly moving tail, the Yellow wagtail has been split into two species: Western yellow wagtail, (Motacilla flava) and Eastern yellow wagtail (Motacilla tschutschensis), which is the shortest tailed of the European wagtails. They may be confused with Grey Wagtails but the Grey Wagtail has a much longer tail, grey upperparts and yellow-green rump. The face and underparts are bright yellow, upperparts are olive-green, the crown and cheeks are yellow-green. Its head colours and markings vary widely between geographical races. Wings and tail are black-brown. Bill, legs and feet are black. The breeding adult male is basically olive above and yellow below. Female Yellow Wagtails are duller with much browner backs and very pale buff-yellow below. Yellow wagtails like damp marshes, meadows and riverbanks and spend much of their time walking and running about on the ground chasing insects disturbed by the feet of domestic animals. They nest on the ground or in long grass, using plants, grasses and stems to build a cup-shape which they line with fur. The Yellow Wagtail is also called the Barley Wagtail.