Oh, third look, that is a 'squirrel proof' feeder. I kid you not... I had one, and I think it took the local thieves a grand total of a day and a half to win that challenge. Some birds wouldn't use it either, apparently afraid to stick their necks into that wire cage. Not exactly the best design I suppose, and it sure didn't work well once they figured it out and told all their friends. *sigh*
I can't find a picture of the one that I had that seemed to hold out the most promise. It was like this, only the outer sleeve of fencing was spring loaded so that when a squirrel got on it, it slid down blocking access to the food ports. BUT whenever there were a few birds on it, it also tended to slide down too, and especially if one landed on it hard enough to move it. This was the one that the squirrels had the worst time with, but the deer cleaned out several nights in a row until I caught one in the process. So squirrel AND deer proof? I gave up...