Black Rhinoceros (Diceros bicornis) Fact Sheet: Behavior & Ecology

Active both day and night

• General activity pattern
• Field observations in Kenya show the following general daily activity pattern:
• Inactive at mid-day, the hottest part of the day
• Mostly inactive between 10:00 AM and 15:00
• Feed primarily before and after inactive periods
• Travel to and drink water in later afternoon
• Mostly observed between 15:00 and sundown
• Specific activity patterns (involving time, location, and activity) vary among individuals, and among consecutive days for a single individual
• Travel patterns, in Kenya (from Schenkel & Schenkel-Hulliger, 1969)
• Rhinos and elephants follow wide trails (several km long), with little vegetation
• Large paths run between water and feeding areas
• Smaller networks of trails, usually not used by elephants, are shared with other wildlife, and used for during foraging

Rest and wallowing

• Rest in the shade
• Sometimes rests and sleeps in shallow water
• Lay down to sleep or rest most often
• Sometimes rest while standing
• Wallow in shallow mud pools or in dust
  
• Often during the heat of the day
• In Tanzania, 90% of wallowing occurred between 16:00 and 18:00 (Goddard 1967)
• Function of wallowing
• Helps regulate body temperature (in mud and water)
• Acts to reduce body temperature
• Protects against ectoparasites (dust)

Social organization

• Do not form organized social groups
• Individuals often congregate in small groups for short periods
• Females with young tend not to socialize with other adults, and may form the only stable associations
• Adult males socialize the least, but do occasionally tolerate the presence of others
• Merz (1991) observed individual treatment by a dominant male towards each of five females during mating, suggesting a more complex social interaction than was previously thought
• Dominance Hierarchy
• Little information exists in the literature regarding social dominance

Territorial behavior and use

• Territory defence
  
• Defense of specific patch or ground unclear
  
• Conflicting reports
  
• Described as territorial; territorial, though shared trails that may bisect one or more territories; not territorial
• Localize at resting spots or "houses" (from Merz 1991)
• Regularly visit preferred areas at customary times each day
• Locations tend to be on high ground
• Some spots are shared by several individuals, some are used only by one or two
• Individuals tend to lie facing downwind
• Often align themselves with the shadow of a large horizontal branch (if present) for better camouflage

Home range

• Undefended area where an animal ranges in search of food
• Size varies seasonally and between habitat types
• May depend on resource availability
• In habitats with an abundance of food and water, home ranges tend to be smaller, and rhino density tends to be higher
• Home ranges of individuals often overlap, and neighbors tend to tolerate each other without aggression

Range size

• In Natal
  
• Males 3.9 to 4.7  km², estimate from radio-tracked individuals
  
• Females 5.8 to 7.7 km², estimate from radio-tracked individuals
  
• In Ngorongoro
  
• 2.6 to 44 km²
• In the Serengeti
• 43 to 133 km²

Aggression

• Little overall aggression
• Encounters of "bluff and bluster" are not uncommon
• Description of aggressive encounters
• Male to male
• Fight occasionally (horn-jousting, head-pushing) or exhibit a threat reaction. Males have also been observed feeding and traveling together. However, most of the time they avoid each other
• Female to Female
• Do not generally act aggressively toward one another. Aggressive encounters are short and often involve facing one another and pushing head to head
• Male and Female
• Usually occurs prior to mating. "Bluff and bluster" displays may last for hours

Olfaction and scent marking

• Highly important form of communication
  • Very important method of communication in rhinos because of their poor eyesight and more solitary nature
• Forms of scent marking
  • Urine spraying
    • Males and females mark bushes or dung piles with a backwards, horizontal spray of urine
    • Both can shoot up to 3 to 4 meters
    • Females do this most often when they are in season,  spraying in short bursts
    • A male may come and spray over a female's scent marking
    • Spraying also occurs along feeding or watering tracks
    • Different than regular urination, and is used in communication
  • Dung Piles
    • Often defecate in the same place repeatedly (="lavatories")
      • Commonly along feeding tracks, near water sources, and scattered randomly throughout the home range
    • "Calling cards"
      • When approaching the dung pile of another individual, a rhino may just sniff, or add to the pile (defecate and scrape). Smelling the dung piles may be a way for rhinos to identify each other
    • Scent trails
      • Dragging the hind feet after defecation enables a rhino to leave a scent trail as it walks through its home range, assisting with orientation. Other individuals may follow the scent trail
    • Often, two individuals traveling together defecate in the same spot (one after the other) or at the same time. This happens with a mother and her young, as well as with two adults
    • Female receptivity
      • Females tend to scrape more vigorously when sexually receptive
    • Courtship
      • Sometimes a male follows a receptive female and scrapes her dung vigorously (flinging it far away) every time she defecates. This makes it more difficult for other males to follow her scent
  • Head rubbing
    • Possible method of scent marking
    • Scrape head against trunks or stumps
    • Horn rubbing less common
  • Flehman
    • Characteristic lip curl behavior; nose wrinkled and head lifted
    • A male behavior, most often
    • Performed when sniffing another's rear end or the urine mark of receptive female
    • Function
      • Thought to aid in bringing scent to the Jacobson's organ (also called vomeronasal organ), located far back in the palate, which detects trace quantities of chemicals in the air (i.e., pheromones).

Visual signals/displays

• Eyes not very expressive
• Tail up
  • Indicates alarm or curiosity
  • Mark of female receptivity when the tail is crooked
• Ears straight up
  • Indicates interest or curious
• Ears flat
  • Indicates anger
  • Sometimes accompanied by a wrinkled nose and grimace
• "Bluff and bluster"
  • Upon meeting another individual, one rhino snorts and swings head side-to-side in a threatening manner, but will gallop away (swinging back around, often repeating this behavior) if the other rhino lunges forward
• "Complex bull ceremony" (described by Schenkel & Schenkel-Hulliger 1969)
  • Possible form of "symbolized aggression" toward a potential rival
  • Occurs when male is alone, or when female is nearby
  • Associated behaviors
    • Sniff a bush
    • Snort, in attack posture
    • Bash bush with rostrum and horn
      • Forceful, side to side movement of the head
    • Trample bush and scrape with hind feet
    • Urinate in bursts over plant
  • Elements and order of events can vary

Vocalization

• Broad vocal repertoire (from Merz 1991 unless otherwise noted)
  • In contrast, vocal communication in white rhinos seems much less common
• Calls

• Lion-like growl and elephant-like trumpet
  • Heard during a fight
• Long snort
  • Signals anger
• Short snort, like a sneeze
  • Sign of alarm
  • May be accompanied with pricked ears and wrinkled nostrils
  • A startle reaction to newcomers
• "High-pitched wonk"
  • Indicates fear
• High-pitched scream
  • Given in extreme fear (terror)
• "Mmwonk"
  • A deep, resonant sound
  • Signals contentment
• Squeak
  • Done with different tones and intonations
  • Possible meanings
    • "I'm lost"
    • "Where are you?"
    • "I'm over here"
    • Other possible emotions that are not yet understood
• Breathing, long and slow, or short and quick
  • Communicates greetings, anxiety, and reassurance
• "Puffing snort"
  • A common greeting when males and females encounter one another (Goddard 1967)

Walk and run

• Fairly sedentary
• Tend to disperse slowly

Learned behavioral associations

• Humans are associated with fear
  
• Exhibit defense behaviors if the scent of humans is detected
• React to alarm reactions of other ungulates
• Poor vision makes this form of learning important for rhinos
• If they detect a possible threat, but are not able to see it from a distance, they often charge it just in case. They have been observed charging tree trunks and termite mounds

Symbiotic relationships

• Cattle Egret
• Bird eats the insects stirred up by rhino as it walks; often sits on its back, but rarely picks off ectoparasites
• Fork-tailed drongo
• Bird sits on branches near rhino, swoops in and out (much like flycatchers) eating insects that are attracted to it
• Does not follow rhino outside its own home range
• Red-billed Oxpecker
• Bird climbs on rhinos (even into ears and nostrils) and plucks off insects
• Will follow rhinos for long distances
• Also serves as alarm when danger approaches (very high pitched alarm call)

Elephants

• Compete for similar food plants
• Rhinos and elephants usually do not interact with each other
• Interactions more likely when food and water resources are scarce
• Cost and benefits of elephants
• Dig wallows and pull down branches with leaves (elephants tend to eat larger branches, rather than the smaller twigs), giving rhinos access to these resources
• Disturb the habitat; cause destruction of trees and bushes

Black Rhinoceros at the Denver Zoo enjoying wallowing

Image credit: © Drew Avery from Flickr. Some rights reserved.

Estes (1991)
Goddard (1967)
Merz (1991)
Schenkel & Schenkel-Hulliger (1969)