White Wagtail

The white wagtail is a slender black, white and grey bird measuring 16.5–19cm, although East Asian forms can reach 21cm. Its long tail is characteristically kept in near-constant motion. This insect-eater favors open country, often near water and human habitation, and hunts most effectively on bare ground where prey remains visible. It also forages on paved urban surfaces. Nests are placed in crevices in walls and comparable natural or artificial structures. (Wikipedia, general species account)