Barber, author of the book The Human Nature of Birds ​ — A Scientific Discovery With Startling Implications, states: “All thoroughly studied animals, including not only apes and dolphins but also ants and bees, have demonstrated totally unexpected basic awareness and practical intelligence. ”
Во својата книга Човечката природа на птиците — научно откритие со неверојатно значење (The Human Nature of Birds — A Scientific Discovery With Startling Implications), д - р Т.