All these sounds, however, reach in muffled form the ear of a human being shut up in a bungalow; hence it is the voices of the night rather than those of the day with which May in India is associated. Most people sleep out of doors at this season, and, as the excessive heat makes them restless, they have ample opportunity of listening to the nightly concert of the feathered folk. The most notable performers are the cuckoos. These birds are fully as nocturnal as the owls. The brain-fever bird (_Hierococcyx varius_) is now in full voice, and may be heard, both by day and by night, in all parts of Northern India, east of Umballa. This creature has two calls. One is the eternal "brain-fever, _brain-fever_, BRAIN-FEVER," each "brain-fever" being louder and pitched in a higher key than the previous one, until the bird reaches its top note. The other call consists of a volley of descending notes, uttered as if the bird were unwinding its voice after the screams of "brain-fever." The next cuckoo is not one whit less vociferous than the last. It is known as the Indian koel (_Eudynamis honorata_). This noble fowl has three calls, and it would puzzle anyone to say which is the most powerful. The usual cry is a crescendo _ku-il_, _ku-il_, _ku-il_, which to Indian ears is very sweet-sounding. Most Europeans are agreed that it is a sound of which one can have too much. The second note is a mighty avalanche of yells and screams, which Cunningham has syllabised as _Kuk_, _kuu_, _kuu_, _kuu_, _kuu_, _kuu_. The third cry, which is uttered only occasionally, is a number of shrill shrieks: _Hekaree_, _karee_, _karee_, _karee_. The voice of the koel is heard throughout the hours of light and darkness in May, so that one wonders whether this bird ever sleeps. The second call is usually reserved for dawn, when the bird is most vociferous. This cry is particularly exasperating to Europeans, since it often awakens them rudely from the only refreshing sleep they have enjoyed, namely, that obtained at the time when the temperature is comparatively low. The koel extends into the Punjab and is heard throughout Northern India.