During puberty: After infancy, the tween and teen years are the period of most rapid change. For girls, the growth spurt begins between 10 and 11 and lasts until around 15; for boys, it starts about two years later and lasts until age 17 or so. Girls typically stop growing about three years after they've had their first period, but boys continue to grow throughout their teens.
The Syrinx. Humans have a larynx, and parrots have a syrinx, located between the voice box and the bronchial tubes. The syrinx branches out in two directions, with each branch opening into a bronchus. Air from a parrot's lungs passes through the syrinx, and the parrot is able to use all of the air to produce sound.
Parrots naturally try to fit in, be it among other parrots or other people. In the wild, parrots use their vocal prowess to share important information and fit in with the flock, says Irene Pepperberg, a research associate and part-time lecturer at Harvard.