Chicken Tractors are small, floorless, portable shelters or coops (usually homemade) placed in pastures that provide free-range poultry access to forage (e.g., grass, weeds, bugs), fresh air, sunlight, and exercise, yet offer a measure of protection from weather and predators. After 'eating down' the vegetation, the shelters are moved to fresh areas in the pastures, allowing the just-abandoned ones to re-grow and be used again. Commonly, laying hens are provided nest boxes in which to lay their eggs. The type and design of shelters are many and varied, as are the materials used to make them, from bed frames and wood pallets to commercially purchased ones.