The common hawk-cuckoo (Hierococcyx varius), popularly known as the brainfever bird, is a medium-sized cuckoo resident in the Indian subcontinent. It bears a close resemblance to the Shikra, even in its style of flying and landing on a perch.The common hawk-cuckoo is a medium- to large-sized cuckoo, about the size of a pigeon (ca. 34 cm). The plumage is ashy grey above; whitish below, cross-barred with brown. The tail is broadly barred. The sexes are alike.