Adult male Blue-headed Wagtail (M. f. flava) Adult male Yellow-crowned Wagtail (M. f. flavissima) Adult, probably female Dark-headed or North Siberian Yellow Wagtail (M. f. thunbergi or plexa), wintering in Kolkata (West Bengal, India) Adult male Sykes' Wagtail (M. f. beema) wintering at Hodal, Faridabad district (Haryana, India) Adult female Turkestan Black-headed Wagtail (M. f. melanogrisea) wintering in Kolkata (West Bengal, India)

The Yellow Wagtail, Motacilla flava, is a small passerine in the wagtail family Motacillidae, which also includes the pipits and longclaws.

Immature Blue-headed Wagtail (M. f. flava)

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 south Asia. The Beringian population winters further down the Pacific coast. Vagrant individuals occur around the winter quarters at migration time. For example, on Palau in Micronesia migrant flocks of this species "? apparently of the Bering Sea Yellow Wagtail, and including many adult males "? are regularly seen, while further north on the Marianas, only the occasional stray individual "? usually females or immatures as it seems "? is encountered.

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 characteristic 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

This species' systematics and phylogeny is extremely confusing. Literally 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 Berinigian region are sometimes separated as Eastern Yellow Wagtail (M. tschutschensis).

Currently accepted subspecies:

Coloration refers to males except when noted.

• M. f. flava Linnaeus, 1758 "? Blue-headed Wagtail.

Blue-gray head with white supercilium and malar stripe in males, much washed with buffish green in females. Breeding: S Scandinavia to France and C European mountain ranges, E 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 gray, reaching down to the cheeks, and without white in males; lighter and washed greenish, with vestigial greenish supercilium in females. Breeding: C and N Scandinavia E to NW Siberia. Winter: E Africa, Indian subcontinent, Southeast Asia.

• M. f. iberiae Hartert, 1921 "? Iberian Yellow Wagtail.

Like flava, but throat white and gray darker, almost black behind eyes. Breeding: SE France, Iberia, Maghreb from Tunisia to Banc d'Arguin. Winter: The Gambia to CAR.

• M. f. cinereocapilla Savi, 1831 "? Ashy-headed Wagtail.

Like iberiae but supercilium absent or vestigial. Breeding: Sicily, Sardinia, Italy, Slovenia. Winter: coastal Tunisia and Algeria, Mali to Lake Chad.

• M. f. pygmaea (A. E. Brehm, 1854) "? Egyptian Yellow Wagtail.

Similar to cinereocapilla, smaller, less bright. Nile delta and lower Nile, resident all year.

• M. f. feldegg Michahelles, 1830 "? Black-headed Wagtail

Like thunbergi but black cap in males, females like a dull thunbergi male above, very washed-out dirty yellowish below, throat white. Breeding: Balkans E to Caspian Sea, S to Turkey, Iran and Afghanistan; also Levant. Winter: C Africa from Nigeria to Uganda and S Sudan.

• M. f. lutea (S. G. Gmelin, 1774) "? Yellow-headed Wagtail.

Head yellow with green neck in males, females like a somewhat more vivid flava female. Breeding: Lower Volga to Irtysh River and Lake Zaysan. Winter: Africa and Indian subcontinent.

• M. f. beema (Sykes, 1832) "? Sykes' Wagtail.

Like flava but head lighter gray, ears washed white; sexes often similar. Breeding: North of lutea, E to Ladakh area. Winter: Indian subcontinent, also E Africa and adjacent Arabia.

• M. f. melanogrisea (Homeyer, 1878) "? Turkestan Black-headed Wagtail.

Similar to feldegg, but white malar stripe and sometimes green neck. Breeding: Volga Delta E around Caspian Sea to N Afghanistan. Winter: Pakistan and NW India to W Nepal, possibly also NE Africa.

• M. f. plexa (Thayer & Bangs, 1914) "? North Siberian Yellow Wagtail.

Males like thunbergi but ears darker, top of head lighter, vestigial supercilium. Females like dull males. Breeding: Siberia between Khatanga and Kolyma Rivers. Winter: India, SE Asia.

• M. f. tschutschensis J. F. Gmelin, 1789 "? Beringian Yellow Wagtail, Alaska Yellow Wagtail, or Eastern Yellow Wagtail.

Both sexes similar to corresponding flava, but gray of head darker; females often very male-like. Breeding: around Bering Strait to NW Canada coast. Winter: regions around South China Sea.

• M. f. angarensis (Sushkin, 1925) "? South Siberian Yellow Wagtail.

Males like plexa, but supercilium more pronounced. Breeding: From S Siberia S through W Transbaikalia to N Mongolia. Winter: SE Asia.

• M. f. leucocephala (Przevalski, 1887) "? White-headed Yellow Wagtail.

Male like flava, but grey of head very pale, almost white. Female like flava females, but head somewhat darker. Breeding: NW Mongolia and adjacent PRC and Russia. Winter: probably India.

• M. f. taivana (Swinhoe, 1863) "? Green-crowned Yellow Wagtail or Kuril Yellow Wagtail.

Like flavissima but daker above, ears much darker, almost black. Sexes similar. Breeding: between ranges of plexa and tschutschensis S via Sakhalin to N Hokkaid?. Winter: Myanmar to Taiwan, S to Wallacea.

• M. f. macronyx (Stresemann, 1920) "? Southeast Siberian Yellow Wagtail.

Males like thunbergi but brighter and more strongly marked overall. Female like in thunbergi but no supercilium. Breeding: SE Transbaikalia E to coast, S to Manchuria. Winter: NW of South China Sea.

• M. f. simillima Hartert, 1905 "? Bering Sea Yellow Wagtail or Short-tailed Grey-headed Wagtail.

Both sexes similar to corresponding flava, but supercilium usually less pronounced. Breeding: Kamchatka and Bering Sea islands, possibly to Aleuts. Winter: SE Asia S to N Australia.

Nominate Blue-headed Wagtail and Yellow Wagtail form a narrow hybrid zone in northern France. Birds from this zone vary in appearance, but one type, which resembles nominate Blue-headed Wagtail (except that the blue tones to the head are paler and more mauve and the white of the head is more extensive, particularly on the throat, ear-coverts, and supercilium) is colloquially referred to as Channel Wagtail.