According to QI just now, parrots don't mimic other birds, animals or noises in the wild.
Isn't that interesting! Why on earth can they mimic human voice when that ability is not something that is actually useful to or even used by them in their natural habitat? What's the point in them having that skill?
God must have known we'd find it amusing, and so slipped a bit of DNA in there for our amusement.