I bought a couple of squirrel-proof bird-feeders and, a few days later, looked out of the window to see a squirrel had removed the squirrel-proof lid from one of them and was stuffing his face. When I chased him off, he further taunted me by taking the squirrel-proof lid with him. He's probably got it hanging on the wall of his drey where he can show all his mates.