Any of about 50 species (especially in the genus Anthus) of small, slender-bodied, ground-dwelling songbirds belonging to the family Motacillidae. Found worldwide except in polar regions and on some islands, they are brownish-streaked and 5–9 in. (12–23 cm) long. They have a thin, pointed bill, pointed wings, and elongated hind toes and claws. Named for their twittering sounds, they walk and run rapidly (but never hop), searching the ground for insects. Their flight is strongly undulating. Their white outer tail feathers show best in flight. See alsowagtail.