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"Cygnus bewicki, Buck's Swan, is white with black feet and bill, the basal half of the latter being yellow, while that colour extends further on the sides. ... where the yellow on the bill does not reach the nostrils, inhabits the Arctic districts from the White Sea to the Pacific, wandering in the winter to Britain, the Mediterranean, South Siberia, China, and Japan." A. H. Evans, 1900

Bewick's Swan

"Cygnus bewicki, Buck's Swan, is white with black feet and bill, the basal half of the latter being…

"Cygnus columbianus. Common American Swan. Whistling Swan. Bill with a yellow spot or blotch in front of eye, usually small, sometimes wanting. Bill less lengthened and expanded terminally than in C. buccinator, the nostrils across the middle; the distance from the anterior angle of the eye to the hind edge of the nostril more than thence to the end of the bill. Tail-feathers normally 20." Elliot Coues, 1884

Whistling Swan

"Cygnus columbianus. Common American Swan. Whistling Swan. Bill with a yellow spot or blotch in front…