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Diceros bicornisblack rhinoceros

By Jennifer Kurnit

Geographic Range

Historically, Diceros bicornis has been distributed throughout Africa, south of the Sahara, with the exception of the Congo Basin. The current range of black rhinoceroses is bounded by Cameroon, Kenya, and South Africa but their distribution within those limits is fragmented. (Brooks, 2002; Grzimek, 2005; World Wildlife Fund, 2004)

Habitat

Black rhinoceroses live in various habitats that range from deserts to grasslands, both tropical and subtropical. They are also present in African forests, especially in areas where grasslands and forests phase into one another. Black rhinos generally stay within 25 kilometers of water. (Grzimek, 2005; Massicot, 2006; World Wildlife Fund, 2004)

Physical Description

Although the color of black rhinoceroses can vary from yellow-brown to dark-brown, the general color is grey. Specific skin color depends on the soil conditions within the habitat of each individual. The skin is naked or hairless, with the exception of short, fringe-like hair on the short and rounded ears. On average, black rhinos have a shoulder height between 1.4 and 1.8 m, a head and body length between 3 and 3.75 m, and a weight between 800 and 1400 kg. Tail length is generally around 0.7 m. Although similar in size, males are normally a little larger than females. (Grzimek, 2005; Lang, 1983; World Wildlife Fund, 2004)

Black rhinos have two horns, one posterior and one anterior, which are made from keratin instead of bone. The anterior horn is normally longer, measuring 42 to 128 cm, while the posterior horn is 20 to 50 cm. In some cases, black rhinos have a third, posterior horn, which is small. Females tend to have longer and thinner horns than males. (Brooks, 2002; Grzimek, 2005; Massicot, 2006; World Wildlife Fund, 2004)

The trait that distinguishes black rhinos from white rhinos is the pointed, prehensile upper lip found in black rhinos, as opposed to the square lips found in white rhinos. This lip is used to pick up food such as twigs. Additionally, black rhinos have smaller heads, shorter ears, and shorter horns than white rhinos. (Brooks, 2002; Lang, 1983; World Wildlife Fund, 2004)

  • Sexual Dimorphism
  • sexes alike
  • male larger
  • sexes shaped differently
  • ornamentation
  • Range mass
    800 to 1400 kg
    1762.11 to 3083.70 lb
  • Range length
    3.0 to 3.75 m
    9.84 to 12.30 ft

Reproduction

Adult black rhinos are typically solitary creatures. However, during mating, black rhino adults come together. Black rhinos are polygynous. Male rhinos begin a courtship by following females, including their dependent offspring, for approximately one or two weeks before mating actually begins; even while sleeping, the male and female remain in contact with one another. Males exhibit certain behavioral characteristics before mating: they walk in a stiff-legged manner and brush their horns along the ground in front of the female. Before copulation begins, many attempts by the male to mount the female are made; if the female is not yet ready, she will make a series of attacks or charges at the male. When insertion is actually achieved, copulation lasts between 20 and 40 minutes. If the mating is unsuccessful, females return to a state of heat within 35 days of the previous copulation. (Garnier, et al., 2001; Garnier, et al., 2002; Grzimek, 2005; Hillman-Smith and Groves, 1994; Massicot, 2006)

Breeding occurs throughout the year but peak breeding season varies by location. Gestation lasts approximately 15 months. Females give birth to one offspring at a time, which usually weighs between 20 and 25 kg. Weaning of offspring typically occurs after 18 months, but offspring remain dependent for up to 4 years. Females achieve sexual maturity at age 5 to 7 years; males reach maturity between 7 and 8 years. (Brooks, 2002; Dollinger and Geser, 2008; Garnier, et al., 2002; Grzimek, 2005)

  • Breeding interval
    Black rhinos breed every 2 to 2.5 years under the most favorable conditions, but interbreeding periods can last up to 4 years.
  • Breeding season
    Black rhinos mate throughout the year, with peak breeding seasons depending on the location of the population.
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Average gestation period
    15 months
  • Average gestation period
    474 days
    AnAge
  • Average weaning age
    18 months
  • Range time to independence
    2 to 4 years
  • Range age at sexual or reproductive maturity (female)
    5 to 7 years
  • Range age at sexual or reproductive maturity (male)
    7 to 8 years

For the first week after birth the offspring is hidden by the mother. After that, the mother and calf use specific vocalizations to find one another: the mother pants and the calf squeals. Black rhino mothers are very protective of their calves, which is why calves walk behind their mothers. This differs from white rhino females, who have their young walk in front of them. Calves are able to browse on their own after one month and able to drink water after 4 to 5 months. Black rhino offspring aren’t weaned until 18 months; after that, the calf remains dependent on its mother for up to 4 years. The basic social unit for females is typically a female and her young offspring, until the offspring is forced into independence by a sibling. (Garnier, et al., 2001; Grzimek, 2005; Massicot, 2006)

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female

Lifespan/Longevity

Typical lifespan in the wild is between 30 and 35 years, with little expectation of exceeding 35 years. In captivity, black rhinos can live over 45 years, with the record being 49 years. Factors that limit lifespan in the wild include poaching for horns and habitat fragmentation. (Brooks, 2002; Grzimek, 2005; Massicot, 2006)

  • Average lifespan
    Status: wild
    35 years
  • Average lifespan
    Status: captivity
    49 years
  • Typical lifespan
    Status: wild
    30 to 35 years
  • Typical lifespan
    Status: captivity
    30 to 45 years

Behavior

Typically, black rhinos are relatively solitary. Males remain solitary until it is time to mate; females reside with their young offspring in a solitary family unit. There are exceptions, as females without young sometimes associate with other females. The largest black rhino group that has been observed so far has been made up of 13 rhinos, but this was a temporary association. (Hillman-Smith and Groves, 1994)

Black rhinos have a sedentary lifestyle and remain in one general area. They are less active during the middle of the day, using mornings and evenings to eat, drink, and move around. When they are startled, they tend to run away from the source. While fleeing, rhinos issue a series of snorts and curl their tails until they calm down. Once the initial scare has passed, the rhino’s curiosity kicks in, and it will examine the source with inquisitive charges. Even though there is severe danger associated with black rhino charges, the charge normally does not end with serious consequences. (Hillman-Smith and Groves, 1994; Massicot, 2006)

In order to remain cool during especially hot times of the day or season, black rhinos roll in mud to get it all over their bodies. They also make trips to local salt licks to get needed nutrients necessary for survival. (Grzimek, 2005)

Adult black rhinos defecate on dung piles as a means of communication, as it reveals to other rhinos how recently an individual was in a certain location. Males also use their feces to mark territories; they kicking their feces to get fecal material on their feet, then move around their home range. They also urinate to mark their home range. When two females meet, they demonstrate little aggression, merely approaching each other and possibly nudging each other with their horns, and then retreating. However, when two males or a male and a female meet, more aggression is exhibited. Upon meeting, a male and female interact in the way described the above. When two males meet, however, violence can very easily ensue. Many times, the less dominant of the two retreats. If not, the males charge at one another, horn first and groaning loudly. The anterior horn provides the rhinos with a very effective weapon during the interaction. (Hillman-Smith and Groves, 1994; Massicot, 2006; Hillman-Smith and Groves, 1994; Massicot, 2006)

  • Range territory size
    2.6 to 133 km^2

Home Range

There is large variation in home range size of black rhinos. Depending on region and habitat, home range can range from 2.6 km^2 to 133 km^2. Habitats with better conditions generally result in smaller home ranges, while poorer conditions result in larger home ranges, presumably because rhinos have to travel further to acquire food and water. Black rhinos are not excessively territorial within their home ranges, but dominant males are more likely to express territorial behavior against other dominant males than females and males lower down in the hierarchical system. (Hillman-Smith and Groves, 1994)

Communication and Perception

Although black rhinos use vision, acoustic, and smell senses, their sense of smell is what they rely on most. They have poor vision, with the ability to see only 25 to 30 m away. Their sense of hearing is good, but not up to the level of their sense of smell. Black rhinos use the pheromones and scents from their feces and urine to mark territories. Additionally, they engage in calls to one another that can take the form of the pant-squeal interaction seen in mothers and their infants to loud roars that signify aggression. When a subordinate male enters the territory of a more dominant male, the combination of calls and territorial scents causes the subordinate male to retreat. (Hillman-Smith and Groves, 1994; Massicot, 2006)

Food Habits

Black rhinos are browsers that feed on items such as twigs, woody shrubs, small trees, legumes, and grass. Black rhinos show a preference for Acacia species, as well as plants in the family Euphorbiaceae. They eat an average of 23.6 kg during the course of each day. Black rhinos use their characteristic prehensile upper lip to grab plants and guide them into their mouths, where their cheek teeth can do the rest of the work. In addition, black rhinos use their horns to gain access to higher branches by breaking or knocking down plants. Scraping bark off of trees is also part of the repertoire of black rhino feeding. (Grzimek, 2005; Hillman-Smith and Groves, 1994; Massicot, 2006)

  • Plant Foods
  • leaves
  • wood, bark, or stems
  • seeds, grains, and nuts

Predation

Humans, Homo sapiens, are the most important predator of black rhinos; however, both lions (Panthera leo) and spotted hyaenas (Crocuta crocuta) sometimes prey on young rhinos. Lions also sometimes attack adults. Black rhinos use their size and strength as a defense mechanism by charging at their predators both to threaten predators and actively defend themselves and their offspring. (Berger, 1994; Hillman-Smith and Groves, 1994)

Ecosystem Roles

Black rhinos and oxpeckers (Buphagus species) are involved in a mutualistic relationship where the oxpeckers eat parasites taken from the rhino’s skin. Additionally, oxpeckers are able to warn rhinos of approaching predators because their vision is much better than the rhino’s vision. Black rhinos are significant herbivores and influence plant communities. (Hillman-Smith and Groves, 1994; Massicot, 2006)

  • Ecosystem Impact
  • disperses seeds
Mutualist Species
Commensal/Parasitic Species

Economic Importance for Humans: Positive

Black rhinos have the potential to help create awareness for conservation efforts. Additionally,they provide educational value both through biology and through art. Black rhino horns are also very valuable for their use in various products, such as traditional Chinese medicine and traditional Yemen dagger handles. The popularity of their horns is a major reason why the species as a whole is in trouble. (Brooks, 2002; Dollinger and Geser, 2008)

Economic Importance for Humans: Negative

Although many charges by black rhinos towards humans and their vehicles turn into innocent advances, some may cause injury or death to humans, or damage to vehicles that results in monetary loss. (Grzimek, 2005)

  • Negative Impacts
  • injures humans

Conservation Status

Black rhinos have been on Appendix I of CITES since 1977. Additionally, black rhinos have been listed since 1980 under the United States Endangered Species Act. Black rhinos are listed as critically endangered by the IUCN Red List. Currently, there are four subspecies of black rhinos: D. bicornis bicornis, D. bicornis longipes, D. bicornis minor, and D. bicornis michaeli. The first subspecies is listed as vulnerable on the IUCN 2008 Red List, and the latter three are all listed as critically endangered. Conservation efforts to preserve black rhinos include establishing a ban against the horn trade, creating fenced sanctuaries for black rhinos to better protect them from poachers, and dehorning black rhinos to decrease incentive for poaching. With these efforts, the total population of 2,400 black rhinos towards the end of the twentieth century increased to 3,100 black rhinos by 2001. (Brooks, 2002; Convention on International Trade in Endangered Species of Wild Fauna and Flora, 2009; IUCN Species Survival Commission, 2008; U.S. Fish and Wildlife Service, 2009; World Wildlife Fund, 2004)

Contributors

Jennifer Kurnit (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor, Tanya Dewey (editor), Animal Diversity Web.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

diurnal
  1. active during the day, 2. lasting for one day.
drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

folivore

an animal that mainly eats leaves.

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynous

having more than one female as a mate at one time

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

sexual ornamentation

one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

young precocial

young are relatively well-developed when born

References

Berger, J. 1994. Science, Conservation, and Black Rhinos. Journal of Mammalogy, 75(2): 298-308.

Brooks, M. 2002. "Black Rhinoceros (Diceros bicornis)" (On-line). Arkive. Accessed April 09, 2009 at http://www.arkive.org/black-rhinoceros/diceros-bicornis/info.html.

Convention on International Trade in Endangered Species of Wild Fauna and Flora, 2009. "CITES-listed Species Database" (On-line). Accessed April 09, 2009 at http://www.cites.org/eng/resources/species.html.

Dollinger, P., S. Geser. 2008. "Black Rhinoceros" (On-line). World Association of Zoos and Aquariums - Virtual Zoo. Accessed April 09, 2009 at http://www.waza.org/virtualzoo/factsheet.php?id=118-003-003-001&view=Rhinos&main=virtualzoo.

Garnier, J., M. Bruford, B. Goossens. 2001. Mating system and reproductive skew in the black rhinoceros. Molecular Ecology, 10: 2031-2041.

Garnier, J., W. Holt, P. Watson. 2002. Non-invasive assessment of oestrous cycles and evaluation of reproductive seasonality in the female wild black rhinoceros (Diceros bicornis minor). Reproduction, 123: 877-889.

Grzimek, B. 2005. "Black Rhinoceros" (On-line). Answers.com. Accessed April 09, 2009 at http://www.answers.com/topic/black-rhinoceros-1.

Hillman-Smith, A., C. Groves. 1994. Diceros bicornis. Mammalian Species, 455: 1-8.

IUCN Species Survival Commission, 2008. "IUCN 2008 Red List" (On-line). Accessed April 09, 2009 at http://www.iucnredlist.org.

Lang, E. 1983. "Diceros bicornis" (On-line pdf). CITES. Accessed April 09, 2009 at http://www.cites.org/eng/resources/ID/fauna/Volume1/A-118.003.003.001%20Diceros%20bicornis_E.pdf.

Massicot, P. 2006. "Black Rhinoceros" (On-line). Animal Info. Accessed April 09, 2009 at http://www.animalinfo.org/species/artiperi/dicebico.htm#Weight.

Morgan, S., R. Mackey, R. Slotow. 2009. A priori valuation of land use for the conservation of black rhinoceros (Diceros bicornis). Biological Conservation, 142: 384-393.

U.S. Fish and Wildlife Service, 2009. "Endangered Species Program" (On-line). Accessed April 09, 2009 at http://www.fws.gov/endangered/.

World Wildlife Fund, 2004. "WWF Factsheet: Black Rhinoceros - Diceros bicornis" (On-line pdf). Accessed April 09, 2009 at http://assets.panda.org/downloads/ecop13blackrhinofactsheet.pdf.

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