Sound Imitation and Speech

Many species can imitate human speech or other sounds, and the results of a study by Irene Pepperberg suggested a high learning ability in an African Grey Parrot named Alex. Alex was trained to use words to identify objects, describe them, count them, and even answer complex questions such as "How many red squares?" with over 80% accuracy. A second example is that of N'kisi, another African grey, which has been shown to have a vocabulary of approximately a thousand words and has displayed an ability to invent as well as use words in context and in the correct tense.

Parrots do not have vocal cords, so sound is accomplished by expelling air across the mouth of the bifurcated trachea. Different sounds are produced by changing the depth and shape of trachea. So, talking parrots are really whistling in different variations. Congo African Grey Parrots (CAG) are well known for their ability to "talk", which may be caused by more control, or stronger trachea. But that does not mean that a Cockatiel (Cockatiels are not well known for their talking ability), could have a greater vocabulary than an African Grey Parrot.