A Skidder is any type of heavy vehicle used in a logging operation for pulling cut trees out of a forest.
Early skidders were pulled by a team of oxen, horses or mules. Starting in the early 1920s, animals were gradually replaced by gasoline-powered crawlers.
Contemporary skidders are tracked or four wheel drive tractors with a diesel engine, winch and steel, funnel-shaped guards on the rear to protect their wheels. They have articulated steering and usually a small, adjustable, push-blade on the front. The operator is protected from falling or flying debris by a steel enclosure.
A skidder is one of the few options for taking out some trees while leaving others and they can also be used for pulling tree stumps, pushing over small trees, and preliminary grading of a logging path.
A positive thing about the skidder is that while wood is being pulled, tree particles and seeds are cultivated into the soil.
One disadvantage of skidder logging in thinning operations is the damage to remaining trees as branches and trunks are dragged against them, tearing away the protective bark of living trees. Another concern is the deep furrows in the topsoil sometimes made by skidders, especially when using tires with chains, which alter surface runoff patterns and increases the costs of forest rehabilitation and reforestation.