Birdsong diversity across the world

Why do skylarks or blackbirds sing such diverse and melodious songs (1, 2), whereas great tits repeat the same two motifs over and over? Differences in sexual selection processes, evolutionary history (phylogeny), or morphological traits could underlie this variation. On page 381 of this issue, Bacquelé et al. (3) report on the evolutionary drivers and distribution of the songs of passerines—the largest bird order—using birdsong recordings from a large open-source database. They reveal that birdsong diversity can be mapped into eight core motifs, whose use and geographical distribution are determined by a trade-off between environmental constraints, evolutionary history, and biological traits.