#down_feather__down  soft fine feathers
  supertype:  #feather__plume__plumage  the light horny waterproof structure forming the external covering of birds
  subtype:  #duck_down  down of the duck
     subtype:  #eiderdown  down of the eider duck
  subtype:  #goose_down__goosedown  down of the goose
  subtype:  #swan's_down  down of the swan
  subtype:  #plumule  down feather of young birds; persists in some adult birds

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