the last first cuckoo

The sound inspired Handel's Cuckoo and the Nightingale (YouTube audio), Beethoven's Pastoral Symphony (the clarinet in the second movement - thanks wiki), Saint-Saëns' Cuckoo in the Depths of the Woods (Youtube audio) and Delius' On Hearing the First Cuckoo in Spring (YouTube audio). No wonder: its two notes form a descending minor third. Two or three weeks from now, you should be hearing it. Round about 14 April. Except you won't.