Although its pugnacity has been exaggerated, the black rhino is unpredictable and can be a dangerous animal, sometimes charging a disturbing sound or smell. It has tossed people in the air with the front horn, and regularly charges vehicles and campfires. When it catches the scent of humans it usually crashes off through the brush and runs upwind, sometimes for several kilometers before stopping. The sense of smell is the primary method of detecting danger. It is very vocal in its communication, using growls, grunts, and most commonly a puffing snort. The usual gait is a fast walk or a bouncing trot. When charging it gallops. Territory is marked with dung piles, and also by spraying urine. They wallow frequently, and roll in dust. They feed primarily in the morning and evening, and have become more nocturnal with the advent of European hunters. Males are solitary. Females are usually found together with a calf and sometimes an older daughter. Those without young join a neighboring female. The young of both sexes also attach themselves to other animals. They are usually tolerant of others that they know in adjacent ranges. Most conflicts involve strangers moving through an area occupied by a clan.