An apparatus for demarcating an area for restricting the freedom of movement of animals that may be in the area for grazing purposes. The demarcation element, as such, may be a cord, band, ribbon, strip, cable, rope or electrified or communication wire which may be two parallel wires separated by a flexible insulating material. The demarcation element is supported by a plurality of vehicles although one or two ends of same may be secured at a reference point. The vehicle is supported by two relatively large wheels which are independently connected to motors and the center of gravity of vehicle is lower than the centers of the wheels which may be perpendicular to the ground or slanted inwardly. The vehicle carries solar panels which may be mounted on the wheels if they are slanted. A connection for the demarcation element is carried on each vehicle which may include a guide member and tightening device. Also measuring devices are included for measuring the length of sections of a demarcation element between vehicles and the angles at which they extend relative to a predetermined direction.