It is also popular in some places for confining horses and pack animals overnight when trail riding, hunting, or at competitions such as endurance riding and competitive trail riding. Typically, one or more strands of wire, synthetic tape or cord are mounted on metal or plastic posts with stakes at the bottom, designed to be driven into the ground with the foot. For a hand-tightened temporary fence of electrified rope or web in a small area, these are usually spaced at no more than 12 to 15 feet (about four metres) to prevent the fencing material from sagging and touching the ground. Larger areas where tools are used to stretch wire may be able to set step-in posts at larger distances without risk that the fencing material will sag. With temporary electric fencing, a large area can be fenced off in a short period. Temporary fencing that is intended to be left in place for several weeks or months may be given additional support by the use of steel T posts (which are quickly driven in with hand tools and unearthed with relative ease, using a leverage device), to help keep the fence upright, particularly at corners. Livestock owners using rotational grazing in set patterns that are similar from one year to the next may permanently drive a few permanent wooden fence posts in strategic locations. Portable fence energizers are made for temporary fencing, powered solely by batteries, or by a battery kept charged by a small solar panel. Rapid laying-out and removal of multiple-strand temporary electric fencing over a large area may be done using a set of reels mounted on a tractor or all-terrain vehicle. For sheep, poultry, and other smaller animals, plastic electric netting may be mounted on insulating stakesthis is also effective at keeping out some predators such as foxes. In practice, once most animals have learned of the unpleasant consequences of touching the fence they tend to avoid it for considerable periods even when it is inactive. However, some animals learn to avoid the shock, either by running under the fence quickly between pulses, or by pushing other individuals through the fence. Animals with thick woolly coats (such as sheep or highland cattle) may learn to push through the fence themselves, using their coats as electrical insulation. Some animals also learn to recognize the slight clicking sound made by some electric fences and thus can