A friend of ours put a metal Slinky on the post that holds the bird feeder. No squirrels!
The Slinky acts like a 'jacket' around the post. Must be something about the coils that the squirrels don't like.
We tried it too - no squirrels.
I kind of miss watching the little critters climbing - don't miss DH and DS yelling at the squirrels, though.