Nightjars, or goatsuckers, to give them their ancient and time-honoured name, are birds that lie up during the day in shady woods and issue forth at dusk on silent wing in order to hawk insects. The most characteristic feature of a nightjar is its enormous frog-like mouth; but it is not easy to make this out in the twilight or darkness, so that the observer has to rely on other features in order to recognise goatsuckers when he sees them on the wing, such as their long tail and wings, their curious silent fluttering flight, their dark plumage with white or buff in the wings and tail, their crepuscular and nocturnal habits, and their large size. Nightjars are as large as pigeons.
The common species of the Nilgiris is the jungle nightjar (Caprimulgus indicus). For a couple of hours after nightfall, and the same period before dawn in the spring, this bird utters its curious call--a rapidly-repeated cuck-chug-chuck-chuck.
Horsfield's nightjar (C. macrurus) is perhaps not sufficiently abundant on the Nilgiris to deserve mention in this essay. A bird which after dark makes a noise like that produced by striking a plank with a hammer can be none other than this species.