The Collaborative International Dictionary of English v.0.48:

Hooper \Hoop"er\, n. (Zool.) [So called from its note.]
   The European whistling, or wild, swan (Olor cygnus); --
   called also hooper swan, whooping swan, and elk. Hoopoe

The Collaborative International Dictionary of English v.0.48:

Whooping \Whoop"ing\,
   a. & n. from Whoop, v. t.
   [1913 Webster]

   Whooping cough (Med.), a violent, convulsive cough,
      returning at longer or shorter intervals, and consisting
      of several expirations, followed by a sonorous
      inspiration, or whoop; chin cough; hooping cough.
      --Dunglison.

   Whooping crane (Zool.), a North American crane (Crus
      Americana) noted for the loud, whooplike note which it
      utters.

   Whooping swan (Zool.), the whooper swan. See the Note under
      Swan.
      [1913 Webster]