My Umbrella Cockatoo is very destructive and doesn't eat fruits or vegetables?

all cockatoos are naturally destructive. i suggest giving him plenty of toys and when he is destroying something just give it to him and there is a good chance he will leave the item he is wrecking and choose the toy instead. As for diet, it all depends on how old he is. Some parrots will not wean (recommended by most bird vets) once they reach a certain age. If you want to wean, limit the amount of sunflower seeds he gets, e.g. one teaspoon each day. With luck, he will begin to peck at the food. However i tried this process with a cockatiel and she ended up starving herself, so i had to stop it and put her on her previous diet. What worked for me was getting her a HEALTHY friend that I knew was already eating healthily. make sure you know your breeders. my bird followed what her friend was doing and now she eats fruit herself! hope this helps! :)