Believe me, even if they dont say a word they can know its meaning.Always tell your grey whats going on.eg, shall we clean your cage,want some toast,want some water, nice bath,want a head scratch and so on. They soon realise what actions these words are linked to.I agree about the whistles,use words in place of whistles.I must say though that my grey and tiel do whistle tunes and things they have picked up and I do love hearing them whistle but both are very good talkers.