Classification and Range
The African warthog belongs to the family Suidae. Suidae includes 19 species in 6 genera distributed throughout Europe, Asia and Africa. These Old World wild pigs, along with New World peccaries and African hippos, make up the sub-order suina of even-toed ungulates. Suina are mostly omnivores with short legs, tusk-like canines and four toes in contrast to the more numerous species of long-legged, ruminant herbivores. Wild pigs in the New World and Australia, for example the Arkansas razorback, are introduced domesticated species that became feral.
Warthogs, a single species or two? Paleontologists long recognized two distinct species, but for years both scientific and popular culture combined them. Current research recognizes two warthog species, the African or Common warthog (Phacochoerus africanus) and the Desert, Cape or Somali warthog (Phacochoerus aethiopicus). They share most characteristics and even inhabit some common range. Key differences occur in skull size and features, and dentition with incisors present in the African and absent in the Desert warthog. Some sources still treat the two species indiscriminately. Identification of regional sub-species requires further research.
The extensive range of the African warthog includes most of sub-Saharan Africa. It stretches across central Africa from east to west and almost to the southern tip. This huge area encompasses the ranges of other wild pigs. Both warthog species live in the Horn of Africa but the Desert warthog inhabits the more arid areas of Somalia, Ethiopia and Kenya. The Giant forest hog and Red river hog live mostly in tropical rainforests but also in some warthog range in Central Africa. The African bush pig shares much of the Common warthog’s eastern and southern African range.
Warthogs inhabit moist and arid savannas, as well as open scrublands and woodlands usually near surface water. Unlike most wild pig species, warthogs avoid thickets and forests.
Warthogs share characteristics typical in wild pigs. They possess medium-sized, barrel-shaped bodies and short legs. They have short necks, longish heads, small eyes, prominent snouts ending in a disk-like nose, and tusks which are upturned lower canines. Males generally have both larger tusks and warts than females and are much larger in size and weight.
Warthogs have some distinctive features. Their heads are very large and as their name indicates, they possess prominent warts with the suborbital pair especially long in males. Their dentition differs from other wild pigs with incisors adapted for grazing and the first two molars replaced by an elongated third molar. The upper canines grow into a long curved tusks and the lower canines protrude forward. Warthog weight places them in the middle between the smallest Pygmy hog of northern India at 13 - 20 pounds (6 - 9 kg) and the Giant forest hog weighing 286 - 605 pounds (130 - 275 kg). Warthogs have longer legs compared to most wild pigs and can run very rapidly.
Head and body length: 3 - 5 feet (1 - 1.5 m)
Shoulder height: 25 - 33 inches (63.5 - 84 cm)
Tail length: 9 - 17 inches (23 -43 cm)
Upper canine tusk length: Male 10 - 35 inches (25.5 - 89 cm); Female 6 - 10 inches (15 - 25.5 cm)
Wart length: up to 6 inches (15 cm)
Adult weight: 110 - 330 pounds (50 - 150 kg); Females 15 - 20% less
Birth weight: 1 - 2 pounds (.45 - .9 kg)
In the wild 7 up to 18 years; in captivity 14 - 18 years.
In the wild: Mostly herbivorous. Eats mainly grasses, but roots, tubers, bulbs, berries and bark of young trees during dry seasons. Will eat carrion and even dung of various herbivores.
At the zoo: Herbivore pellets( grain), grass hay, fruits and vegetables.
Reproduction - Seasonal breeding
Warthogs become sexually mature between 18 to 20 months; however, males usually lack experience and strength to breed successfully until 4 years of age. A few months after the rainy season ends, females enter estrus and attract male attention by urinating in a hunched position. Both sexes may have multiple mates. Males compete for breeding rights with frontal head butts protected by the facial warts. Usually the loser runs off squealing and unharmed; however, a rare slash from a lower tusk could be fatal. The winner courts the female with rhythmic chants. He nudges and sniffs her, does lateral displays and rests his head on her rump. This continues until she stands for mating.
Births occur during the dry season after a gestation of almost 6 months (170 - 175 days), the longest of all pigs. The sow isolates herself and farrows (gives birth to a litter) in a burrow. The small litter averages 2 to 4, but up to 8. The tiny altricial piglets require the protective warmth of the burrow and the sow during their first days. They emerge from the burrow after 6 to 7 weeks, begin grazing by two months, and wean by five or six months. Warthogs have a single litter each year timed to the rainy and dry seasons. By two years, young females begin breeding and live in a sounder (wild pig social group). Sounders may contain a single female or related adult females and offspring. Two year old males leave their sounders to live in a bachelor group or alone. Older males usually lead solitary lives and only join sounders during breeding season.
Life Cycle - Living on the Savanna
Eating: Life on the savanna alternates between rainy and dry seasons. After the rains, the savanna erupts with new vegetation. Warthogs have special adaptations for eating grasses. With very short necks and relatively long legs for pigs, how do warthogs reach the short new shoots? They kneel on their wrist joints. Hard callous pads form there enabling warthogs to shuffle along for extended periods while feeding. They graze using their lips and unique sharp incisors. During dry periods, warthogs use their front feet and mobile, strong snouts to uproot grass rhizomes, bulbs and tubers from the hard dry soil. These foods may provide them with water. Warthogs can survive extended periods without drinking water during the dry season.
Heating: Behavioral adaptations provide for temperature variations. Warthogs have no layer of sub-cutaneous fat. For warmth, they huddle together in underground burrows. While they could use their snouts to excavate, warthogs commonly use large abandoned aardvark dens and may even line them with grass. Pigs have no sweat glands for cooling. Warthogs live near water holes that provide mud wallows for cooling during the heat of the day.
Communicating: Warthogs, like all wild pigs, live highly social lives. They usually forage in family groups accompanied by constant communication in squeaks, squeals, snorts, chirrups, growls and grunts. They also communicate with scent from various glands to mark their ranges and also during courtship and friendly encounters. Their senses of hearing and smell are acute and stronger than their vision. Warthogs signal alarm with snorts and grunts, and also visually with lowered mane and ears, and by running with tails upright.
Surviving: Many warthog predators live on the savanna. These include lions, leopards, cheetah, hyenas, African wild dogs, crocodiles, and humans. Jackals and eagles predate on piglets. Warthogs utilize varied survival techniques. Sheltered in their burrows at night, warthogs avoid nocturnal predators such as leopards. Although normally diurnal if disturbed by human activity, warthogs switch to nocturnal foraging. Warthogs pay attention to alarm calls from oxpeckers, birds which frequent their backs and feed on parasites. When fleeing, warthogs reach speeds of 30 to 34 miles per hour (48 - 55 kph). The sounder escapes into burrows with the young rushing in head first. Adults back into the den with formidable heads and tusks facing outward. Warthogs erupt in a burst of speed when leaving the safety of the burrow. Whether inside the den or exiting it, razor sharp lower tusks provide good defense.
Location at the Zoo
Our warthogs are located in the African Savanna biome near the Krugeri lions. Other savanna animals include patas monkey, plains zebra, reticulated giraffe, fringe-eared oryx, Grants gazelle, ostrich and other savanna birds. Another wild pig, the Visayan warty pig (Sus cebifrons), is located in the Tropical Asia biome across from the Elephant Pool.
With an estimated population of 250,000 existing throughout widespread regions of Sub-Saharan Africa, Common warthogs have the status of Least Concern by IUCN Red List of Threatened Species. Drought conditions, land use conversion to agriculture, and human persecution impact regional populations. Farmers kill them for raiding wheat, rice, bean and groundnut crops. Domestic livestock owners eradicate them due to disease concerns. African wild pigs are symptomless carriers of the African swine fever virus that is lethal to domestic animals. Warthogs are favored hosts of the Savanna tsetse fly. These blood-sucking insects can infect humans with sleeping sickness and domestic livestock with ngana. People also hunt warthogs for their ivory and meat. Despite all this, the warthog population remains strong and substantial numbers live in protected areas of parks and reserves.
Sources and Suggested Reading
“Family Suidae: Pigs” http://www.ultimateungulate.com/Cetartiodactyla/Suidae.html
“The Genus Phacochoerus: The Common Warthog and the ‘Desert’ Warthog” IUCN/SSC Pigs and Peccaries Specialist Group http://data.iucn.org/dbtw-wpd/edocs/1993-055.pdf
“Mammals: Warthog” http://www.sandiegozoo.org/animalbytes/t-warthog.html
“Phacochoerus africanus” http://www.iucnredlist.org/apps/redlist/details/41768/0
“Suidae: pigs” http://eol.org/pages/7681/overview
“Warthog Phacochoerus africanus” http://animals.nationalgeographic.com/animals/mammal/warthog/
“Wild Pigs and Boars” The Encyclopedia of Mammals. edited by Dr David Macdonald. pp 500-503. 1999
Resnick, J. P. 1994. Cats. Kidsbooks, Inc., Chicago, IL. 29 p.
Zoobooks. 1992. Big Cats. Wildlife Education, Ltd., San Diego, CA. 16 p.
Zoobooks. 1992. Lions. Wildlife Education, Ltd., San Diego, CA. 18 p.