The Collaborative International Dictionary of English v.0.48:

Bellbird \Bell"bird`\, n. [So called from their notes.] (Zool.)
   (a) A South and Central American bird of the genus
       Casmarhincos, and family Cotingid[ae], of several
       species; the campanero.
   (b) The Myzantha melanophrys of Australia.
       [1913 Webster] bell-bottomed

WordNet (r) 3.0 (2006):

bellbird
    n 1: any of several tropical American birds of the genus
         Procnias having a bell-like call