White Wagtail

The white wagtail is a slender bird, 16.5 to 19 cm (6.5 to 7.5 in) in length; the East Asian subspecies are slightly longer, measuring up to 21 cm (8.3 in). It has the characteristic long, constantly wagging tail of its genus. Its average weight is 25 g (0.88 oz) and the maximum lifespan in the wild is about 12 years. 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. The pied wagtail, named after the naturalist William Yarrell, exchanges the pale grey colour of the nominate subspecies with black in males, and dark grey in females and juveniles, but is otherwise identical in its behaviour. Other subspecies, the validity of some of which is questionable, differ in the colour of the wings, back, and head, or other features. Some races show sexual dimorphism during the breeding season. As many as six subspecies may be present in the wintering grounds in India or southeast Asia and here they can be difficult to distinguish. Phylogenetic studies using mtDNA suggest that some morphological features have evolved more than once, including the back and chin colour. Breeding M. a. yarrellii look much like the nominate race except for the black back, and M. a. …

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. It also breeds in the mountains of Morocco and western Alaska. It occupies a wide range of habitats, but is absent from deserts. White wagtails are residents in the milder parts of its range such as the western half of Europe and the Mediterranean, but migratory in much of the rest of its range. Northern European breeders winter around the Mediterranean and in tropical and subtropical Africa, and Asiatic birds move to the Middle East, India, and Southeast Asia. Birds from the North American population also winter in tropical Asia.

The most conspicuous habit of this species is a near-constant tail wagging, a trait that has given the species, and indeed the genus, its common name. In spite of the ubiquity of this behaviour, the reasons for it are poorly understood. It has been suggested that it may flush prey, or signal submissiveness to other wagtails. A study in 2004 has suggested instead that it is a signal of vigilance to potential predators.

Diet and feeding. The exact composition of the diet of white wagtails varies by location, but terrestrial and aquatic insects and other small invertebrates form the major part of the diet. These range from beetles, dragonflies, small snails, spiders, worms, crustaceans, to maggots found in carcasses and, most importantly, flies. Small fish fry have also been recorded in the diet. The white wagtail is somewhat unusual in the parts of its range where it is non-migratory as it is an insectivorous bird that continues to feed on insects during the winter (most other insectivorous birds in temperate climates migrate or switch to more vegetable matter).

Breeding. White wagtails are monogamous and defend breeding territories. The breeding season for most is from April to August, with the season starting later further north. …

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. The white wagtail is the national bird of Latvia, and has been often mentioned in its folk songs. It also appears in the logo of the Latvian Ornithological Society. The pied wagtail has occasionally been called "water wagtail"; and in Ireland "willie wagtail", not to be confused with the Australian species Rhipidura leucophrys which bears the same common name.