How to deter cockatoos?

I have been feeding wild cockatoos from my 3rd floor apartment window for the past few weeks. Now I have to stop doing this because my neighbours have complained about the falling sunflower seeds. I have shut all of the windows for the past 6 days but the cockatoos are still arriving. They scream, bang on the windows, have put holes in my mosquito nets and have started pulling the rubber seals off my (and my neighbours) windows. How can I deter them but not harm them?