The Golden Horde
By my estimate, my flock of lesser goldfinches (10 grams each), with a little help from their house finch cousins, have eaten something over 15 million nyjer seeds since I installed the feeder outside my window a few months ago. That's a lot of nyjer seeds, even at 150,000 seeds per pound, especially since they shell and eat every one. I would think their thumbs would get tired.
Or, since they don't actually have thumbs and are forced to use beak and tongue instead, their tongues.