Is there somewhere you can suspend the birdfeeder that they can't jump to it from? Even raise it and lower it using a high test fishing line that can take the weight but where a squirrel can find no purchase.
And in other news I was checking around to see who has a cheap copy of Faster (the Rock's last flick, and an awesome anti-hero flick btw) and I noticed that Excalibur is finally out on Blu-ray. Dunno how that one slipped by me. Love that film!