I bought this feeder because of squirrels constantly feeding on my bird feeders. I was a lot of fun watching squirrels trying to steal seed from this feeder. First they would try to pry the top open and failed. They would then get onto the ring at the bottom of the feeder and get spun off as the ring started to spin rapidly and "flipped off". Unfortunately I had about 10 squirrels come to my deck to try to get the Sunflower seed. My deck was filthy with squirrel waste. My solution was to switch to Safflower seed instead of Sunflower seed. Squirrels don't like the taste of Safflower seed and after a few days stopped trying to get to the feeder as did Grackles.