Phacochoerus africanus

Geographic Range

Warthogs ( Phacochoerus africanus ) are found outside forested areas in Africa, from Mauritania to Ethiopia and south to Namibia and eastern South Africa.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

Habitat

Common warthogs are found in open and wooded savannas, grass-steppes, and semi-deserts in Africa. Common warthogs prefer open areas and avoid rainforest and severe desert. They are found on Kilimanjaro up to an elevation of 3000 m and along coastal regions of Africa. Common warthogs often utlilize formerly wooded areas that have been cleared for pastures.

The distribution of common warthogs is limited by cover, human disturbance, and suitable foraging. Warthogs require areas to cool-off in order to cope with high temperatures. These include wallows. They also require areas in which to stay warm in the evening, such as burrows.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland

• Other Habitat Features
• agricultural agricultural

Physical Description

Common warthogs weigh 50 to 150 kg with females being 15 to 20 percent lighter than males. Head and body length is 900 to 1500 mm. Shoulder height ranges from 635 to 850 mm. Common warthogs have large upper tusks that are 255 to 635 mm long in males and 152 to 255 mm long in females. As their name suggests, warthogs have three pairs of facial warts, comprised of cartilaginous connective tissue. The three types of warts are: 1) the suborbital warts, which may grow as long as 15 cm in males; 2) the preorbital warts, which do not develop as much in females; and 3) the submaxillary warts, which have white bristles.

The head is large with a mane that goes down the spine to the middle of the back. There is sparse hair covering the body. Color is usually black or brown. Tails are long and end with a tuft of hair. Common warthogs do not have subcutaneous fat and the coat is sparse, making them suceptible to extreme environmental temperatures.

Common warthogs can be distinguised from Cape warthogs by the number of incisors. Common warthogs have two upper and four to six lower incisors, in contrast to Cape warthogs, which lack incisors.

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• ornamentation ornamentation

Reproduction

Common warthogs have a polygynandrous mating system. Both males and females have many mates. Males do not defend territories, but when females are in estrus ritualized fighting between males does occur. Fighting involves pushing and striking with the head and blunt upper tusks. The more dangerous lower tusks are rarely used, and injuries or fatalities are rare. Adult males are usually solitary and join female groups briefly for mating. Females attract boars by sight and smell by urinating in a hunched position.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Mating in common warthogs is seasonally dependent. Females usually become fertile 4 to 5 months after the rainy season has ended and give birth during the dry season. Common warthogs are sexually mature at 18 to 20 months, although males do not typically mate until 4 years of age. Common warthogs are recorded to have the longest gestation of all pigs, ranging from 170 to 175 days. Litters range in size from 1 to 7 piglets, with an average of 3 piglets per litter. Piglets are weaned at about 21 weeks of age.

Female P. africanus spend most of their lives in groups called soundings, but prior to giving birth they become solitary. Females give birth in a burrow, which is important in regulating the body temperature of the piglets, since young warthogs can not maintain their own body temperature the first few days of life. Young warthogs spend six to seven weeks in the burrow before venturing out with the mother. Male warthogs do not leave their mother until they are 2 years of age. Female warthogs leave their mother when they are sexually mature, but may return to the sounding later in life.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Common warthog sows isolate themselves in burrows to give birth, then stay undergroud with the altricial piglets for the first week. Piglets remain in the den for the first 6 to 7 weeks, and the sow returns often to nurse them. Piglets accompany the mother everywhere after the 6 to 7 weeks in the den. They are weened at about six months. Other sows in the sounding may nurse the young if they are closely related. Offspring may stay within the sounding for up to two years. Males do not play a role in parental care.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female
• post-independence association with parents
• extended period of juvenile learning

Lifespan/Longevity

Researchers in the eastern Selous Game Reserve, Tanzania found the average lifespan of a warthog was 7 to 11 years. Other literature indicates that warthogs may live as long as 18 years.

Infant warthogs are suceptible to both extreme temperatures and predation, which is why the juvenile survival rate is less than 50% in the first year of life. Other common causes of mortality in adult warthogs are predation, human disturbance, hunting, and disease.

Behavior

Common warthogs live in family groups called soundings. A sounding usually consists of females and their young. Males usually disperse after 2 years of age and become solitary or form bachelor groups. Females stay in a sounding except when they are pregnant. Soundings can consist of up to 18 members. Common warthogs are primarily diurnal and take refuge at night in burrows. Warthogs commonly utilize aardvark holes for sleeping at night. They cope with high temperatures by wallowing in mud or water and cope with low temperatures by sheltering in burrows and huddling together. They are primarily diurnal when there is not human disturbance.

• Key Behaviors
• terricolous
• diurnal diurnal
• motile motile
• migratory migratory
• social social

Home Range

Common warthogs do not exhibit territorial behavior. Different groups of warthogs have extensive overlap of home ranges. Warthogs share resting, feeding, drinking, and wallowing sites. Occassionaly warthogs shift their home ranges in response to seasonal water shortages. Home range size of common warthogs can vary from 0.62 km^2 to 3.3 km^2.

Communication and Perception

Common warthogs have poor eyesight, but their senses of hearing and smell are keen. A common warthogs, when alarmed, run with its tail upright as an alarm for conspecifics. During friendly encounters, common warthogs rub their preorbital glands against each other. Female warthogs use frequent urination to demonstrate their readiness for mating to boars. During fights among conspecifics, the loser typically squeaks and flees and the victor usually leaves the losing individual alone. During fights and mating, warthogs grunt and grind their teeth.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Common warthogs are primarily grazers but also feed on roots, berries, bark of young trees, and occassionaly carrion. They are specialized for grazing short grasses by being able to lower themselves close to the ground on their wrist joints, which are calloused and padded. Common warthogs use their snouts and tusks to excavate rhizomes and bulbs. Rhizomes and bulbs may also provide water for common warthogs during periods of drought. Common warthogs eat their own dung and the dung of rhinoceroses, African buffalos, waterbucks, and francolins.

• Primary Diet
• omnivore omnivore

• Animal Foods
• carrion carrion

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

• Other Foods
• dung

Predation

The predominant predators of common warthogs are lions . Common warthogs avoid nocturnal predators by being active during the day and sheltering in burrows at night. They also use the warning calls of red-billed and yellow-billed oxpeckers to avoid predators. They are fast runners and usually avoid attack by fleeing. Common warthogs change their activity patterns to avoid humans. In areas with human disturbance, warthogs often become more active nocturnaly.

Ecosystem Roles

Common warthogs have a mutualistic relationship with birds, such as red-billed and yellow-billed oxpeckers. The birds are able to feed on the parasites carried by common warthogs while the warthogs are able to rid themselves of these pests. It is thought that the rooting of the common warthog aids in plant growth by aerating the soil. They are also prey to lions and leopards.

• Ecosystem Impact
• soil aeration soil aeration

Economic Importance for Humans: Positive

Common warthogs are valued for their meat, both for local consumption and trade in cities. Common warthogs are easy to hunt and have a potential of increasing population size by 39% annually, which makes them popular on game ranches. Rooting by common warthogs may also help to churn up soil and aerate the land, which in turn aids in plant growth. They are also a source of food for birds, such as red-billed and yellow-billed oxpeckers, that eat parasites off of their bodies.

• Positive Impacts
• food food
• body parts are source of valuable material

Economic Importance for Humans: Negative

Common warthogs are known to cause damage to various crops, such as rice-fields and peanut crops. Cattle ranchers also see common warthogs as competitors for grazing in southern Africa. Common warthogs are suceptible to diseases which may be transmitted to domestic pigs, such as the tick-borne African swine fever virus. They also are a host of the tsetse fly, which can cause African sleeping sickness in humans.

• Negative Impacts
• injures humans
  • carries human disease
• crop pest
• causes or carries domestic animal disease causes or carries domestic animal disease

Conservation Status

Currently common warthogs are not a protected species, but many populations are in serious decline due to overhunting in unprotected areas. Wildlife reserves are trying to protect warthogs, but outside of these areas there are no regulations on hunting. Several zoos have tried captive breeding with very little success.

Additional Links

Encyclopedia of Life

Contributors

Eileen Creel (author), Humboldt State University, Brian Arbogast (editor, instructor), Humboldt State University.

Nancy Shefferly (editor), Animal Diversity Web.

References

Anderson, E., G. Hutchings, N. Mukarati, P. Wilkinson. 1998. African swine fever virus infection of the bushpig ( Potamochoerus porcus ) and its significance in the epidemiology of the disease. Veterinary Microbiology , 62: 1-15.

Boshe, J. 1984. Demographic characteristics of the warthog population of the eastern Selous Game Reserve, Tanzania. African Journal of Ecology , 22: 43-47.

Cumming, D. 1970. A contribution to the biology of warthog ( Phacochoerus africanus ) in the Sengwa region of Rhodesia . Grahamstown: Rhodes University.

Grubb, P. 1993. Wart hog. Pp. 377 in Mammal Species of the World , Vol. 1, 2 Edition. Washington and London: Smithsonian Institution Press.

Randi, E., J. D'Huart, V. Lucchini, R. Aman. 2002. Evidence of two genetically deeply divergent species of warthog, Phacochoerus africanus and Phacochoerus aethiopicus in East Africa. Mammalian Biology , 67: 91-96.

Somers, M. 1997. The sustainability of harvesting a warthog population: assessment of management options using simulation modelling. South African Journal of Wildlife Research , 27/2: 37-44.

Vercammen, P., D. Mason. 1993. The warthogs. Status Survey and Conservation Action Plan, 1: 1-11.

2005. "African Wildlife Foundation" (On-line). Accessed March 11, 2005 at http://www.awf.org/wildlives/153 .

1989. Grzimek's Encyclopedia of Mammals. Pp. 40-44 in Grzimek's Encyclopedia of Mammals , Vol. 5, 1 Edition. New York: McGraw-Hill.

2005. "Sea World/Busch Gardens" (On-line). Animal Bytes. Accessed March 11, 2005 at http://www.seaworld.org/AnimalBytes/warthogab.html .

1991. Walker's Mammals of the World. Pp. 1060-1062 in Walker's Mammals of the World , Vol. 2, 1 Edition. Baltimore: John Hopkins University Press.