Watched my neighbor go through the exact same thing with his feeders. He started with one cheap sock of nyjer seed about four years back and now he's got three feeders going and they fight over them like little yellow bees. What got me was how the first couple years he saw almost nothing and figured the seed was bad or the spot was wrong, but then one spring they just showed up out of nowhere and never left. He swears it was the thistle plants he let go wild in the back corner that finally brought them in, not the feeders at all. Anyway 14 birds every morning is a real crowd, you must be going through seed like crazy by now. Do they stick around all winter for you or do they take off when it gets cold?