Tundra Swans, Cygnus columbianus (link to allaboutbirds.org), are majestic, breathtakingly marvellous birds to watch. As they migrate through our part of the world on their way to their breeding ground, many stop and rest in harvested corn fields. When resting they congregate in large flocks that sometimes number in the hundreds or thousands.
They are also wary of humans, flying away when we become too intrusive. I was fortunate to approach within about 100 meters. After taking this photo I withdrew to leave them in peace.