Here's a novel innovation. The Squirrel Slinky fits on 1" poles (only 1"poles)

The Slinky is a spring loaded tube, that when a Squirrel mounts the pole, the Squirrel pulls down on the Slinky and the spring lets it slide back down the pole. When the Squirrel jumps off, the Slinky returns to it's original position, and waits for the Squirrel to try again.

At £11.95 the Slinky is great value for money, and it has to be said, a most entertaining and humane way of frustrating the marauding Squirrel.