Put a Slinky on the Pole
While this may seem silly when you're at the toy store buying a slinky for the first time in decades, it's actually a great way to create an inexpensive barrier to squirrel entry. Put a slinky just below your bird feeder so that squirrels will hit it right before they get to the feeder. The slinky will slide back down the pole, giving the squirrel a nice elevator ride to the ground.