The wagtails form the passerine bird genus Motacilla. They are small birds with long tails which they wag frequently.
Wagtails are slender, often colourful, ground-feeding insectivores of open country in the Old World. Among their most conspicuous behaviours is a near constant tail wagging, a trait that has given the birds their common name. In spite of the ubiquity of the behaviour and observations of it, the reasons for it are poorly understood. It has been suggested that it may flush up prey, or that it may signal submissiveness to other wagtails. Recent studies have suggested instead that it is a signal of vigilance that may aid to deter potential predators.
