The Collaborative International Dictionary of English v.0.48:

Kagu \Ka"gu\, n. (Zool.)
   A singular, crested, grallatorial bird (Rhinochetos
   jubatus), native of New Caledonia. It is gray above, paler
   beneath, and the feathers of the wings and tail are
   handsomely barred with brown, black, and gray. It is allied
   to the sun bittern.
   [1913 Webster]