chitter

from WordNet (r) 3.0 (2006)

chitter
    v 1: make high-pitched sounds, as of birds [syn: {chitter},
         {twitter}]

from The Collaborative International Dictionary of English v.0.48

Chitter \Chit"ter\, v. i. [Cf. {Chatter}.]
   1. To chirp in a tremulous manner, as a bird. [Obs.]
      --Chaucer.
      [1913 Webster]

   2. To shiver or chatter with cold. [Scot.] --Burns.
      [1913 Webster]