The western yellow wagtail (Motacilla flava) 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. It is resident in the milder parts of its range, such as western Europe, but northern and eastern populations migrate to Africa and south Asia. It is a slender 15–16 cm long bird, with the characteristic long, constantly wagging tail of its genus. It is the shortest tailed of the European wagtails. The breeding adult male is basically olive above and yellow below. In other plumages, the yellow may be diluted by white. The heads of breeding males come in a variety of colours and patterns depending on subspecies. The call is a high-pitched jeet. This insectivorous bird inhabits open country near water, such as wet meadows. It nests in tussocks, laying 4–8 speckled eggs. Systematics Motacilla is the Latin name for the wagtail; although actually a diminutive of motare, " to move about", from medieval times it led to the misunderstanding of cilla as "tail". The specific flava is Latin for golden-yellow. This species' systematics and phylogeny is extremely confusing. Dozens of subspecies have been described at one time or another, and some 15-20 are currently considered valid depending on which author reviews them. In addition, the citrine wagtail (M. citreola) forms a cryptic species complex with this bird; both taxa as conventionally delimited are paraphyletic in respect to each other. The populations of the Beringian region are sometimes separated as eastern yellow wagtail (M. tschutschensis). Currently recognized subspecies Colouration refers to males except when noted. M. f. flava Linnaeus, 1758 – blue-headed wagtail Blue-grey head with white supercilium and malar stripe in males, much washed with buffish green in females. Breeding: southern Scandinavia to France and central European mountain ranges, east to Urals. Winter: sub-Saharan Africa. M. f. flavissima Blyth, 1834 – yellow-crowned wagtail Yellow-green head with a brighter yellow supercilium. Females markedly paler below than males. Breeding: Britain and English Channel coast. Winter: Africa. M. f. thunbergi Billberg, 1828 – dark-headed wagtail or grey-headed wagtail Head dark grey, reaching down to the cheeks, and without white in males; lighter and washed greenish, with vestigial greenish supercilium in females. Breeding: central and northern Scandinavia east to north-west Siberia. Winter: eastern Africa, Indian subcontinent, Southeast Asia. M. f. iberiae Hartert, 1921 – Iberian yellow wagtail Like flava,