The Collaborative International Dictionary of English v.0.48:

Larker \Lark"er\, n. [See 3d Lark, for sense 1, and 1st
   Lark, for sense 2.]
   1. A catcher of larks.
      [1913 Webster]

   2. One who indulges in a lark or frolic. [Colloq.]
      [1913 Webster]