The Yellow Wagtail is characterized by a slender body, a long tail that it often wags up and down, and gray plumage on its back, with a bright yellow underside. The Yellow Wagtail feeds mainly on insects. Unlike the White Wagtail, the Yellow Wagtail is more closely associated with aquatic environments, ranging from mountain streams and rivers to lakes. It nests between May and August, building its nest in cavities or under bridges, where the female lays 4–6 eggs.