The eastern yellow wagtail (Motacilla tschutschensis) is a small passerine in the wagtail family Motacillidae, which also includes the pipits and longclaws. It was often classified as a subspecies of the Western yellow wagtail. This species breeds in temperate Asia and has a foothold in North America in Alaska. Populations migrate to south Asia and Australia. Vagrant individuals occur around the winter quarters at migration time. For example, on Palau in Micronesia migrant flocks of this species – apparently of the Bering Sea yellow wagtail, and including many adult males – are regularly seen, while further north on the Marianas, only the occasional stray individual – usually females or immatures as it seems – is encountered. It is a slender 15–16 cm long bird, with the characteristic long, constantly wagging tail of its genus. The breeding adult male is basically olive above and yellow below. In other plumages, the yellow may be diluted by white. The heads of breeding males come in a variety of colours and patterns depending on subspecies. The call is a characteristic high-pitched jeet. This insectivorous bird inhabits open country near water, such as wet meadows. It nests in tussocks, laying 4–8 speckled eggs. The Acanthocephalan parasite Apororhynchus paulonucleatus was discovered in the colon and cloaca of the Eastern yellow wagtail.