The Collaborative International Dictionary of English v.0.48:

Prey \Prey\, v. i. [imp. & p. p. Preyed; p. pr. & vb. n.
   Preying.] [OF. preier, preer, L. praedari, fr. praeda. See
   Prey, n.]
   To take booty; to gather spoil; to ravage; to take food by
   violence.
   [1913 Webster]

         More pity that the eagle should be mewed,
         While kites and buzzards prey at liberty. --Shak.
   [1913 Webster]

   To prey on or To prey upon.
   (a) To take prey from; to despoil; to pillage; to rob.
       --Shak.
   (b) To seize as prey; to take for food by violence; to seize
       and devour. --Shak.
   (c) To wear away gradually; to cause to waste or pine away;
       as, the trouble preyed upon his mind. --Addison.
       [1913 Webster]