These bird feeders won't get raided by squirrels

Popular Science 

The Yankee Flipper takes an active approach to fending off furballs. When anything heavier than 8 ounces lands on the bottom perch, a battery-powered motor spins it, flinging the pest away. This way, it won't hang around trying to claw its way in. At nearly a foot-and-a-half tall, the polycarbonate tube holds up to 5 pounds of avian snacks. Squirrels are heavier than the birds you want at your feeder, a fact that the Brome SquirrelBuster Plus uses to its advantage.