The Collaborative International Dictionary of English v.0.48:

Caw \Caw\ (k[add]), v. i. [imp. & p. p. Cawed (k[add]d); p.
   pr. & vb. n. Cawing.] [Imitative. [root]22 Cf. Chough.]
   To cry like a crow, rook, or raven.
   [1913 Webster]

         Rising and cawing at the gun's report.   --Shak.
   [1913 Webster]