We have a lot of birds around here. We also have more than our share of squirrels. Since this area has become a haven for pigeon freaks - excuse me - fanciers - who cut down every tree on their property in pursuit of faster homing (I guess), our property has become something of a haven for a lot of birds and squirrels.
I don't mind feeding the squirrels, but they aren't happy with their basket of sunflower seeds. They blow through those in record time and go looking for more. On to the bird feeders! So I've been on the hunt for a squirrel proof feeder for some time. I finally found it, I think. I got it at Lowes, and it is called Garden Treasures ®"Squirrel-Be-Gone" Squirrel Proof Wild Bird Feeder.

I purchased this sucker shortly before we left on vacation. It operates very simply. there are little feeder windows with perches for the birds, but if anything heavier than a bird lands on it, climbs on it, reaches for it, these sensitive little springs effectively close the feeder windows. The bird seed is no longer accessible.
The feeder is hung from one of those shepherd's hooks just far enough away from the ground and any wall or tree or any type of purchase for the squirrel. I sat and watched a squirrel become so frustrated he was literally running around in circles before finally admitting defeat and leaving. He jumped, he climbed, he pounced, he reached.......every single thing he tried closed those little feeder cups.