The Black rhino is unpredictable in its behaviour 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. If a Black rhino catches the scent of humans, it usually runs away, sometimes for quite a distance before stopping.
Black rhinos are more active (feeding, drinking and walking) in early morning and late afternoon to evening. Black rhinos are also active at night, often feeding, drinking, and walking outside their core areas and in more open habitat than during the day. The most intensive feeding takes place during early morning and evening.
Sleeping occurs either standing or lying down. Black rhino react swiftly when disturbed from rest, usually standing up and facing the source of disturbance. Because they have poor eyesight they may not locate the disturbance easily. Being curious animals, they will walk or trot forward to find out what is going on.
Black rhino usually run away if they catch a human’s scent and only charge if they feel threatened. Black rhinos frequently wallow in shallow water holes. The water helps them to keep cool, they coat themselves in mud, probably to gain a protective coating against biting insects.
The horn is continually worn away by rubbing. Each rhino develops its own rubbing habits and horn-wear patterns. Rhinos from different areas can have horns with different shapes.
Black rhino can move extremely fast. They can run at 55 kilometres per hour change direction surprisingly quickly. They can run right through scrub and bushes.
Adult Black rhinos have no predators, although lions, leopards and hyenas may kill calves and sub-adults. Evidence of predator attacks are sometimes seen in the form of mutilated ears or missing tails. According to Brain, Forge and Erb (1999) sub-adult Black rhinos of a certain age appear particularly susceptible to lion predation in Etosha National Park. The sub-adults at this age have just left their mothers and are still relatively small. Brian, Forge and Erb (1999) also report that over a 13 year period in the Hluhlwe / Corridor / Umfolozi game reserve complex, there were no records of lion predation on Black rhinos, although there was strong evidence to suggest that there was spotted hyena (Crocuta crocuta) predation on small calves. It is estimated to be a 16 % loss of rhinos less than two years old to predation. Black rhinos are also capable of killing their predators. Reports vary from females with calves killing lions and a sub-adult female killing an adult hyena.
Group structure: Black rhinos are predominantly solitary, the most commonly observed group structures being adult females with young. Other groups of various ages and genders occur, but they are usually temporary. The largest temporary group reported in one study included 13 Black rhinos. Recent studies indicate that Black rhinos are more social than previously thought and particularly around waterholes at night. Females are usually are found together with a calf and sometimes an older daughter. Females without young may temporarily join a neighbouring female. Sub-adults frequently associate with other Black rhinos. Only fully adult males become solitary, and even then they may form temporary groups that move and feed together. Male Black rhinos only become socially mature when they establish a set territory, in which they spend most of their time and do most of their feeding. Females settle into their own home range near the time of birth of their first calf. Female home ranges can overlap. Dominant bulls do not overlap with their home ranges.
Relations and communication: Adult male Black rhino tend to live on their own, except when courting females. Among males, there are dominant and subordinate animals. Subordinate rhino are often sub-adults who must defer to an established territorial bull or risk a fight. Young bulls are often killed or injured in these interactions. Old males which can no longer defend their territories also die in fights, or become confined to a small area.
Black rhinos that share a part or all of their home range exhibit a familiarity with one another instead of the aggression that they exhibit to total strangers. Black rhino advertise their presence in their range to other rhino by spray-urinating and scraping their dung on the ground next to a path; and also by defecation on well-developed dung-piles. Male rhino spray-urinate and scrape more than females, and territorial (dominant) males keep more dung-piles in and around their range.
The explosive puffing snort of an alarmed Black rhino is the sound most clearly associated with this species by people who work with them. An appealing high-pitched whine or squeal is another sound made by this species. The high-pitched whine is used by calves to attract its mother’s attention, a male may use it to court a female, and all Black rhinos use it when in pain or in distress.
An adult male and female, with the female’s young if she has one, form temporary associations for mating during the female’s oestrus. For a few days, when the female is in oestrus, a pre-mating bond may develop between the bull and the cow, and the pair remains together during resting and feeding. They even sleep in contact with each other. Young are sometimes attacked by males during courtship. The young return to the female when the oestrus is over. Although at times several bulls may court a female simultaneously without apparent antagonism, serious fights and frequent deaths result from conflicts over females in oestrus. Rhinos are renowned for the extended duration of copulations, which last between 20 minutes and an hour or longer, with multiple ejaculations.