The Collaborative International Dictionary of English v.0.48:
Whooper \Whoop"er\, n. One who, or that which, whooops. [1913 Webster] Woopher swan. (Zool.) See the Note under Swan. [1913 Webster]WordNet (r) 3.0 (2006):
whooper n 1: rare North American crane having black-and-white plumage and a trumpeting call [syn: whooping crane, whooper, Grus americana] 2: common Old World swan noted for its whooping call [syn: whooper, whooper swan, Cygnus cygnus]