The Collaborative International Dictionary of English v.0.48:

Knobbler \Knob"bler\, n. (Zool.)
   The hart in its second year; a young deer. [Written also
   knobber.] --Halliwell.
   [1913 Webster]

         He has hallooed the hounds upon a velvet-headed
         knobbler.                                --Sir W.
                                                  Scott.
   [1913 Webster]