The Collaborative International Dictionary of English v.0.48:

Squawk \Squawk\ (skw[add]k), v. i. [imp. & p. p. Squawked
   (skw[add]kt); p. pr. & vb. n. Squawking.] [See Squeak.]
   To utter a shrill, abrupt scream; to squeak harshly.
   [1913 Webster]

   Squawking thrush (Zool.), the missel turush; -- so called
      from its note when alarmed. [Prov. Eng.]
      [1913 Webster]