Biology
The Ontogeny of Vocal Learning in Songbirds
Quick fact
Some songbirds, like zebra finches, have a critical period in early life for learning their song; if they don't hear a tutor's song during that window, they will never develop a normal song.
Why this is interesting
Have you ever wondered why a young bird doesn't automatically sing its species' song perfectly? It turns out that, just like humans, songbirds must learn to communicate.