Parrot Alex is the smartest. He could distinguish seven colors and five shapes, and understand the concept of “more“, “less”, “same”, “different“, “over” and “under“. According to his researcher, Irene Pepperberg, the level of intelligence of a parrot corresponded to 5-year-old child, and the level of emotional development – 2-year-old.
When Alex was 29, it was announced that he realizes the meaning of zero.
The last thing the parrot said to the researcher before he died was: “You be good. I love you”.