We don't have synonyms for mute swans yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are mute swan.
(n) :
A species of white plumaged swan, Cygnus olor, having a distinctive orange bill with a black tip, native to Eurasia and widely introduced elsewhere as an ornamental waterbird.
(n) :
A species of white plumaged swan, Cygnus olor, having a distinctive orange bill with a black tip, native to Eurasia and widely introduced elsewhere as an ornamental waterbird.