The swan is a water bird, both graceful and fierce, famed for its death song; it was said to bring good luck. It’s found in the arms of Dale as early as 1387 [DBA2 153]. The young swan was also called a “cygnet”, especially for canting, as in the arms of Synnot, c.1470 [DBA2 178].
The swan is rousant or rising by default, as in the famous badge of Bohun, later of Henry IV [HB 109]. However, it’s very frequently found naiant in Society heraldry; this too is a period posture, as in the Belgian arms of Lanchals, c.1488 [von Volborth, The Art of Heraldry, 1987, p.90].
For related charges, see goose.
The Prince of Cynagua bears: Quarterly argent and Or, a swan rousant, wings elevated and addorsed sable, maintaining in its sinister foot a laurel wreath vert.
Amina de Talavera bears: Azure, a swan naiant argent crowned Or.
Nikolai Mikhailovitch bears: Or, three swans rousant gules.
Thomas Blackswann the Lefthand bears: Argent, three swans rousant contourny sable.