Trumpeter swans are the largest of North American waterfowl. They are resident year round throughout much of their range, but migratory in other parts. The wing feathers of trumpeters were once prized as the finest quill pens and they were hunted to near extinction by the early 20th century. Now relatively common, they are nearly indistiguishable in appearance from their smaller cousins, tundra swans. The rust colored head and neck on some adults comes from feeding in water containing iron oxide.