Yesterday we saw a House Finch flying erratically around the bird feeder, up and down, left and right. It turned out that it was a fledgling trying to land on the feeder perch. His mother was coaching.
Update: looking as closely as possible, I think this young House Finch only has one eye! It may not survive for long, and has been continuing to fly erratically. I will keep the bird feeder stocked up to help him, but its long-term propects do not look good.