How to convince my dad in letting me have a macaw?

I'll be 16 and I've had 11 parakeets 8 of which I still have . I've wanted a macaw since I was 11 but my parents would only let me have parakeets. I really want a Macaw it would be in a house w/ my dad my parakeets my collie ( who loves my parakeets) my cat ( he don't mess with the birds) ..... 2 turtles and my 4 hamsters. How do I convince him to get me a Macaw for my birthday?- I have all the money but $100 for the bird. He has danced around my request for a macaw for years now and keeps giving me parakeets ( I love my parakeets) I just want a bigger bird to train.My parakeets can talk even. I'm home schooled threw online so I have so much times on my hands and want to give a Macaw a good home..... How do I convince him to let me have the bird ..... I graduate in 2 months and REALLY want to be a avain vet.