SWAN (AS., OHG. swan, Ger. Schwan, swan; probably connected with Lat. sonus, sound, Skt. svan, to resound) . A water-bird of the duck family, the seven or eight species of which constitute the subfamily Cygninæ, composed mainly of the genera Cygnus and Olor, the latter distinguished by the great keel of the breast-bone being divided into two plates, between which lies the curvature of the windpipe—an organ greatly developed in this group. Swans are larger in body than geese, and are recognizable by their long arched necks, enabling them to reach food on the bottom of streams and shallow ponds without diving. They nest mostly in high latitudes, constructing on the ground a rude receptacle of rushes and the like for the half a dozen greenish eggs. They feed chiefly on vegetable substances, as the seeds and roots of aquatic plants, but also on fish-spawn, of which they are great destroyers. They hiss like geese, and strike with their wings in attack or defense.
The typical and most familiar example of the tribe is the tame or ‘mute’ swan (Cygnus olor), which is about five feet in entire length, and weighs about thirty pounds. It is known to live for at least fifty years. The male is larger than the female. The adults of both sexes are pure white, with a reddish bill; the young (cygnets) have a dark bluish-gray plumage, and lead-colored bill, surmounted by a black knob at the base of the upper mandible, and with a black nail. (See Colored Plate of Water Birds.) In its wild state this species is found in Eastern Europe and in Asia; in a half-domesticated state it has long been a common ornament of ponds, lakes, and rivers. The ancients ascribed to it remarkable musical powers, which it was supposed to exercise particularly when its death approached. It has, in reality, a soft low voice, plaintive, and with little variety, to be heard chiefly when it is moving about with its young.
Swans, according to the law of England, are birds royal; those actually kept by the Crown had a mark, and the King's swan-herd once was an important person. The royal swans of the Thames are so marked to this day by notches and lines cut upon the beak, and the process of collecting and marking them annually is called ‘upping.’ Other Old World swans are the Polish, with an orange bill; the whistling swan or ‘whooper;’ Bewick's swan, and the aberrant black swan (Chenopis atrata) of Australia, which is comparatively small and deep black except the white wing-quills and the red bill.
The North American swans belong to the genus Olor. The most common species (Olor Columbianus) breeds in the far North and is seen in the United States only on its migrations, which extend to the Gulf of Mexico; and it is very rare east of the Alleghanies. The trumpeter swan (Olor buccinator), noted for its sonorous cry, breeds from Iowa and Dakota northward, and winters southward to the Gulf. It is one of the largest species, measuring 5½ feet in length. The black-necked and duck-billed swans are South American species. See Duck, and authorities there cited.