Lake of the Woods 250. ompson Yellowstone June 14, 1932 Much of the time both birds preened while floating in the water and calling. They would call even when their bills were buried in their feathers. The bill was repeatedly dipped in the water while preening. The nostril was nearer the tip than the base of the bill. A lump was on the bill between eye & nostril but the entire bill and eye were jet black as were also the feet. During the preening, there was much yawning, and stretching of feet and wings. One swan lay partly on its side in the water and stretched its foot out above the water several times. When the bills were wet they were very flashing in the sunlight. The eyes and lump (lump about same size as eye) sparkled repeatedly. As near as we could tell, the birds were pulling some sort of aquatic plant from the bottom in their feeding. Grass was seen in the bill of one once. Sometimes they tip up as surface feeding ducks do. At 2:45 we had to leave the lake. The swans followed us completely around the lake calling.