The Collaborative International Dictionary of English v.0.48:

Skidder \Skid"der\, n.
   One that skids; one that uses a skid; specif.: (Logging)
   (a) One that skids logs.
   (b) An engine for hauling the cable used in skidding logs.
   (c) The foreman of a construction gang making a skid road.
       [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

skidder
    n 1: a person who slips or slides because of loss of traction
         [syn: skidder, slider, slipper]
    2: a worker who uses a skid to move logs
    3: a tractor used to haul logs over rough terrain