I've got (2) quart sized feeders and they'll empty a half gallon in under 8 hrs. It's damn near a full time job keeping them filled. Glad I work from home..

What amazes me is that every spring, if I don't have them out when the lil bastages move in, I've seen them hover around where the feeders normally hang.. I can't imagine there being any scent there, so I'm going to assume the little buggers are return visitors and remember where the feeders normally are..

Edit: Like someone else said, I've taken the feeders down and hung the feeder off my finger before and they'll come and sit on the feeder eventually. Once you get a mess of them around your place, don't wear red outside. They'll come and "buzz the tower" on you..