Squirrel deterrent

I've tried to set up the ground feeder that the men bought me as a present. The squirrel managed to raid  it almost straight away by squeezing through the bars of the guard mounted over the feeder. I have tried again and there was a dunnock pootling around in it today for the few seeds left. I've heard that chilli powder will deter squirrels but won't put off birds. We'll see.