The white wagtail (Motacilla alba) is a small passerine bird in the family Motacillidae, which also includes pipits and longclaws.

The species breeds in the Palearctic zone in most of Europe and Asia and parts of North Africa; it also has a toehold in western Alaska as a scarce breeder.

However, mtDNA cytochrome b and NADH dehydrogenase subunit 2 sequence data suggests that the white wagtail is itself polyphyletic or paraphyletic (i.e. the species is not itself a single coherent grouping).

[7] Other phylogenetic studies using mtDNA still suggest that there is considerable gene flow within the races and the resulting closeness makes Motacilla alba a single species.

[10] There are a number of other subspecies, some of which may have arisen because of partial geographical isolation, such as the resident British and Irish form, the pied wagtail M. a. yarrellii, which now also breeds in adjacent areas of the neighbouring European mainland.

Other subspecies, the validity of some of which is questionable, differ in the colour of the wings, back, and head, or other features.

[11][12][13][14] Phylogenetic studies using mtDNA suggest that some morphological features have evolved more than once, including the back and chin colour.

The song is more regular in white than pied, but with little territorial significance, since the male uses a series of contact calls to attract the female.

[18] This species breeds throughout Eurasia up to latitudes 75°N, only being absent in the Arctic from areas where the July isotherm is less than 4 °C.

Northern European breeders winter around the Mediterranean and in tropical and subtropical Africa,[24] and Asiatic birds move to the Middle East, India,[19] and Southeast Asia.

These range from beetles, dragonflies, small snails, spiders, worms, crustaceans, to maggots found in carcasses and, most importantly, flies.

For second broods in the subspecies personata the female alone builds the nest, which is a rough cup assembled from twigs, grass, leaves and other plant matter, as the male is still provisioning the young.

[31] Though it is known to be a host species for the common cuckoo, the white wagtail typically deserts its nest if it has been parasitised.

[19] In a number of cities, notably Dublin, large flocks gather in winter to roost.

[1] They have featured on stamps from Bahrain, Belarus, Belgium, Finland, Georgia, Hong Kong, Hungary, Iceland, Iran, Ireland, Israel, Jersey, Kuwait, Latvia, Norway, Poland, the United Kingdom and Vietnam.

[33] The white wagtail is the national bird of Latvia, and has been often mentioned in Latvian folk songs.