Songbirds are not born with songs in their heads, but learn them from others. And as in a game of telephone, it would seem natural that, over generations, the songs might change.

That is what happens with many species, some more dramatically than others. The songs of indigo buntings change so much, for example, that songs that are five years apart are almost completely different.

Image Credit... Natural History Museum, London

But with other species, the songs are more stable. Now, thanks to some old audio recordings, researchers have determined just how stable some songbirds’ songs can be.