The Collaborative International Dictionary of English v.0.48:

Rotche \Rotche\, n. (Zool.)
   A very small arctic sea bird (Mergulus alle, or Alle
   alle) common on both coasts of the Atlantic in winter; --
   called also little auk, dovekie, rotch, rotchie, and
   sea dove.
   [1913 Webster]

WordNet (r) 3.0 (2006):

little auk
    n 1: small short-billed auk abundant in Arctic regions [syn:
         little auk, dovekie, Plautus alle]