Struggles with squirrels

We have had troubles with squirrels hogging all the birdseed and using it up very quickly.  Squirrels are cute, but we much prefer the variety of birds around here that want some food.  Rowen tried to discourage the squirrels by the spikes he added to the arrangement.  However, they have tough bellies and were not deterred.  The other thing we tried was putting cayenne pepper on the food, which also failed to limit their appetites.  Now we are sprinkling birdseed on the deck rail and the deck floor.  The squirrels still come, but they can't rake in the food as easily.  It gives the birds a fair chance at the food.