Reading a book can change your life. Reading a book about wild birds changed mine.
The book mentioned "close living" with birds, and I wondered, "Might living in proximity with a parrot provide motivation for the bird to learn language?"
My thoughts wandered to something a high school English teacher had said, "If you want to own a word, you must use it in three sentences." Armed with ideas from the book and a teacher's admonition, I began interacting with my bird.
It is now many years later and my bird has taught me a great deal. The specifics are not important here, but suffice it to say that they are better at learning language than anyone previously suspected.
My efforts are documented in the book called Another Kind of Mind: A Talking Bird Masters English. It is the only book of its kind documenting the ability of a bird to earn language, not simply to repeat things. The parrot's vocabulary seems unlimited as she has spoken more than 6000 different expressions.