Common Hawk-Cuckoo

The common hawk-cuckoo, popularly the brainfever bird, is a pigeon-sized cuckoo, about 34 cm long, resident in the Indian subcontinent. It is ashy grey above and whitish below with brown cross-barring, with a broadly barred tail and a yellow eye-ring. It looks and flies much like a shikra, and small birds and squirrels may raise an alarm as if it were a hawk (Wikipedia, general species account).

It is a brood parasite that lays in babblers' nests. In summer the male gives loud, repeated three-note calls, rendered as brain-fever, rising to a crescendo, which may go on all day and around dusk and dawn. Nationally Endangered (Sri Lanka National Red List 2012, listed as Cuculus varius).