How Animals Develop Regional Accents
The song of the hermit thrush sounds a bit like an orchestra warming up: the experimental trill of a flautist, a violinist testing his vibrato on a few high notes, all just beginning to suggest a larger melody. This undulating song can be heard throughout North America in the summer. But moving east to west, a keen listener might notice that the bird’s repertoire changes: lower notes introduce each song, like a viola has been added to the mix, and the trills that follow are shorter.
For biologists, this change is the anthem of evolution.
Read more on Atlas Obscura.