Music: Benjamin Britten Cuckoo, cuckoo, what do you do? In April, I open my bill; In May, I sing night and day; In June, I change my tune; In July, far far I fly; In August, away I must. Cuckoo, cuckoo... what do you do? In April, I open my bill; In May, I sing night and day; In June, I change my tune; In July, far far I fly; In August, away I must. Cuckoo, cuckoo!