From Wikipedia: A small passerine in the wagtail family Motacillidae, which also includes the pipits and longclaws. This species breeds in much of temperate Europe and Asia. It is resident in the milder parts of its range, such as western Europe, but northern and eastern populations migrate to Africa and south Asia. It is a slender 15 to 16 cm long bird, with the characteristic long, constantly wagging tail of its genus. It is the shortest tailed of the European wagtails. 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 colors 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.

In Kenya Yellow Wagtails pay close attention to cows as they graze. Grasshoppers and other insects fleeing the mouth of the cow are seen and taken prey. Several other birds like cattle egrets and starlings also hunt for insects in close proximity to cattle and other ungulates. Wagtails may be taking the smaller insects? It also appears that they stay closer the muzzle of the animals as they feed. The bird below was observed at Kapsabet, western Kenya, December 2014.