Many also rely on an extended process of habituation during which the individual animals concerned learn to treat humans in open safari vehicles as a neutral part of the landscape, neither a threat nor an opportunity. The vehicles drive slowly when in sight of wildlife; the occupants stay still, silent, and sitting, and the guides watch the wildlife carefully to detect signs of agitation, and move the vehicles slowly away if need be. In private reserves where the animals have been habituated for a long period, tour options may include game drives at night in open vehicles, e.g. to watch lion and leopard. When traveling on food, horseback, or by canoe, however, a guided group will avoid such potentially dangerous situations, generally traveling only during the middle of the day and avoiding areas where wildlife might hide or sleep.