The Collaborative International Dictionary of English v.0.48:

Incage \In*cage"\, v. t. [imp. & p. p. Incaged; p. pr. & vb.
   n. Incaging.] [Cf. Encage.]
   To confine in, or as in, a cage; to coop up. [Written also
   encage.] "Incaged birds." --Shak.
   [1913 Webster]