Cognitive and communicative abilities of Grey parrots

This paper presents results of almost 30 years of study of the cognitive and communicative activities of Grey parrots (Psittacus erithacus), conventionally regarded as mindless mimics. These studies have demonstrated that Grey parrots can solve various cognitive tasks and acquire and use English speech in ways that often resemble those of very young children. Examples include the concepts of same/different, colour, size and shape. The parrot Alex can also recognize and distinguish numbers up to six, and spontaneously demonstrated his ability to grasp the concept of “none”. Given the evolutionary distance between birds and mammals, these results have intriguing implications for the evolution of intelligence, the study of comparative intelligence, and the care and maintenance of birds held in captivity in zoos and as companion animals.