Now, a new paper describes how the cowbird chicks may learn to recognize and sing their own species’ songs.

"We kind of opened the paper with this existential question," said Sarah London, a neuroscientist at the University of Chicago. "How do you know who you are if no one's shown you who you are?"

London and her colleagues, including Matthew Louder of the University of Tokyo and Mark Hauber of the University of Illinois at Urbana-Champaign, found that part of the answer appears to be a "password" -- a simple call that the birds know innately. This password activates learning mechanisms in young cowbirds' brains, prompting them to remember other vocalizations they hear at the same time.   

Males raised in isolation will develop something that resembles a cowbird song, but with important differences. In the wild, young males change their developing songs to match the songs of other cowbirds in their vicinity, leading to regional differences or "accents."

Read more Inside Science