"I'm so glad we had this time together / Just to have a laugh or sing a song," sang the stars ... of her iconic The Carol Burnett Show sign-off song "So Long" with Clarkson!

Sing a song of sixpence, a pocket full of rye Four and twenty blackbirds baked in a pie When the pie was opened the birds began to sing Oh wasn't that a dainty dish to set before the king!

Songbirds sing intricate songs for mate attraction and territorial defense, which they learn early in life. How do young birds learn how to sing? What controls this complex behavior? Aa Aa Aa The ...