Domesticated in Britain probably as early as the 10th century, mute swans were considered the exclusive property of the British Crown for centuries and could only be owned by persons possessing a permit from the Royal Swan Master.
Unlike other swans, which use their extremely long, coiled trachea (windpipe) to produce loud calls, mute swans have a short and straight trachea. While they may not be able to make the resonant calls of other swans, they are far from mute. Irritated birds may hiss, snort, grunt, bark or even snore!
Females carry the silver-grey cygnets frequently for the first ten days after they hatch.