Get a bunch of 1 liter or quart soda bottles. Drill a small hole in the bottom of each and sting them on a wire then attach the ends of the wire to two trees. Hang bird feeders from the wire in between the soda bottles. When the squirrels attempt to get to the feeders by climbing out on the wire they'll have to step on the soda bottles which will then spin and the squirrels fall to the ground. It works great!!
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