Swamp sparrows are copycats. Young birds learn the notes of birdsong and copy them, passing the songs through generations. Some of these specific trills may go back thousands of years, according to a new simulation.

Stephen Nowicki at Duke University in North Carolina and his colleagues recorded the song repertoires of 615 swamp sparrows living in marshes in New York’s Hudson Valley. These birds memorise the songs they hear in the first 8 weeks of their life, and the following spring, they develop precise renditions of around 3 specific clusters of …