The only reliable way to deter squirrels from bird feeders is to use hot peppered bird seed. Squirrels (and other rodents) hate the taste of capsaicin, but birds are immune and happily chow it down. Train your neighborhood squirrels by starting out with 100% of hot peppered seed like Wild Delight Sizzle N Heat Bird Food and then gradually dilute this expensive seed with regular stuff. I have not tried this, but you can make your own by mixing a cayenne oil like Flaming Squirrel Sauce with your usual seed. — KK