So I've had my cockatiel for a little over a year now and he was just a baby when I got him. He is very bonded with me and can be very vocal as he chirps on his own. However, I've been trying to teach him new simple tunes to whistle and I've been repeating simple words to him over and over trying to get him to repeat them, but he just doesn't seem interested. Any tips on things I can do to help him learn?