I am not familiar with your part of the country at all , that said, how much pressure is put on the place during deer season? What methods of deer hunting, i.e., driving, stands, maybe even dogs? That could have pushed them off of place. Seems to me, in the winter, birds want to be in the best cover they can find, close to food sources. Side note, I know Nebraska quail and pheasant seasons go till the end of this month.