It is a motorized vehicle with an attachment that can rapidly gather and cut a tree before felling it.
Feller is a traditional name for someone who cuts down trees, and bunching is the skidding and assembly of two or more trees.
A feller buncher performs both of these harvesting functions and consists of a standard heavy equipment base with a tree-grabbing device furnished with a chain-saw, circular saw or a shear—a pinching device designed to cut small trees off at the base.
The machine then places the cut tree on a stack suitable for a skidder, forwarder, or yarder for transport to further processing such as delimbing, bucking, loading, or chipping.
Some wheeled feller bunchers lack an articulated arm, and must drive close to a tree to grasp it.
In cut-to-length logging a harvester performs the tasks of a feller buncher and additionally does delimbing and bucking.