The bird feeder in question is a coated wire cage, hanging down from a little metal swinging roof. The squirrels needed only swing the roof up, stick most of their bodies into the feeder, get the thing in their teeth, and haul.
I figured a simple X of wire over the top of the cage would prevent this, since the squirrel wouldn't be able to fit through the sides, and the bird bar certainly wouldn't. And in this, it appears, I was quite correct.
Because this morning, as I was taking the recycling out, I looked up to discover that the clever little beasts, rather than attempt to haul the bird bar out, had simply eaten the hinges on the cage, (no mean feat, since they had to cling to the tree, stretch a foot into space, hold the roof up, and get their teeth through a fairly large plastic whatsit at a very bad angle) dropping the whole thing to the dirt. Presumably it then travelled hence to Squirrelville, since I found neither hide nor hair of it. All that remains is the little metal roof, swinging forlornly in the wind, creaking, a ghost feeder of the Old West (or rather recent south, anyhow.)
Had I an unlimited budget, I could go onto the next phases of this madness, purchasing astonishing squirrel flipping devices that promise to launch our rodent friends into low earth orbit for a mere 79.95. But I don't think I will. The birds seem very happy with the hot pepper suet, and the one squirrel I've seen go for it then dedicated himself to licking the ice on the deck railing with great gusto. So I'll stick to the suet for now.
But someday, my squirrely friends...there will be a reckoning...