Motor driven, battery powered, weight activated perch ring. Birds will not set it off, not even larger species like Woodpeckers and Cardinals. But the minute a squirrel hops on to the perch, the motor is triggered and the feeder begins spinning, taking the squirrel for a whirl before it loses its grip and is thrown gently from the perch. The seed tube is generous in height, making it impossible for squirrels to hang down from the top reach seed. The four feeding ports are easily accessible via the perch ring. With a large 5 lb. capacity, you don’t need to refill your feeder every day.