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.
How to Identify Parrots. There are certain characteristics which set parrots apart from other birds. These include an upper mandible which can move independently from the rest of the skull, and a zygodactyl toe configuration, with two toes pointing forward and two pointing backward on each foot. Other birds may have one of these features but only parrots have both.