Eastern Yellow Wagtail

The eastern yellow wagtail is a slender bird 15–16 centimetres long, with the long, constantly wagging tail of its genus. The breeding adult male is basically olive-green above and yellow below; in other plumages, particularly first-winter birds and many females, the yellow may be diluted by white. The heads of breeding males vary in colour and pattern with subspecies. The bill and legs are black, and a long, not strongly curved hind claw reliably separates it from the western yellow wagtail, which has a shorter, more curved one. (Wikipedia, general species account)

Formerly classed as a subspecies of the western yellow wagtail, it was split in 2003 when genetic data showed the older classification was paraphyletic with respect to the citrine wagtail. It breeds in the East Palearctic and has a foothold in Alaska. Most birds migrate to Southeast Asia and Australia for the winter, with the non-breeding range reaching west to eastern India and Sri Lanka, and migrant flocks are regularly seen on Palau in Micronesia. (Wikipedia, general species account)