The Collaborative International Dictionary of English v.0.48:

Ululate \Ul"u*late\, v. i. [imp. & p. p. Ululated; p. pr. &
   vb. n. Ululating.] [L. ululatus, p. p. of ululare to howl,
   yell, shriek.]
   To howl, as a dog or a wolf; to wail; as, ululating jackals.
   --Sir T. Herbert.
   [1913 Webster]