How does a RollerFeeder work?

A seed container is bolted to a shaft. The outer shell spins around the seed container in a clockwise or counter-clockwise rotation. The shell includes a perch platform, a counter-balance, and a window opening that permits access to the feed ports by small birds. When a rodent animal or large bird climbs or lands on the feeder, the rotating shell dislodges the unwanted visitor and closes access to the seed tray.