A new study has shown that the songs of more than 3,000 passerine bird species are composed from just eight basic sound motifs. Using machine learning on over one lakh recordings, researchers identified three types of trills, three types of whistles, atonal chaotic notes and harmonic stacks. On average a species uses about five motifs, with the selection shaped mainly by evolutionary history, habitat and social behaviour. Tropical rainforest birds tend to sing simpler songs that carry better, whereas birds of temperate regions use more complex, information-rich songs.