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Hylochoerus meinertzhagenigiant forest hog

By Barbara Lundrigan and Jennifer Bidlingmeyer

Geographic Range

Forest hogs are found in Africa, mainly in the equatorial forests and grasslands west, west of the Rift Valley. There are a few scattered small populations northeast of Lake Victoria, and several scattered larger populations from Nigeria to Senegal. There are three recognized subspecies, each with distinct ranges. The forest hog H. m. ivoriensis inhabits the area near the Ivory Coast, H. m. rimator lives in two areas near the west and central equatorial zone and coexists in the east equatorial zone with H. m. mienertzhagheni, the "true" giant forest hog. A potential fourth subspecies exists to the north of H. m. mienertzhagheni. (d'Huart, 1993; Estes, 1991)

Habitat

The giant forest hog prefers the dense shade of thickets and bushes. This suid ranges through a variety of forest types, including dry forests; humid, lowland forests; and montane forests (up to 3,800 m). H. meinertzhageni is most common near permanent water sources, especially where there is a thick understory cover. However, it does venture out into clearings and grasslands to feed. (d'Huart, 1993; Estes, 1991)

  • Range elevation
    3800 (high) m
    12467.19 (high) ft

Physical Description

Standing approximately 1m high and 190 cm long, Hylochoerus meinertzhageni adults have a huge broad head, and males have pads of naked, inflated skin near their eyes. Both sexes have small, straight tusks that flare outward (to 30 cm) and teeth modified for grazing and browsing. The giant forest hog has large, pointed ears and bristly hair on its body and tail. Color is slate gray with some lighter hair on the face. The male's cheek pads contain scent glands, and this hog also has a preputial scent gland. Females are slightly smaller than males and have 4 mammae. (Estes, 1991; Walker, 1968)

  • Sexual Dimorphism
  • male larger
  • Range mass
    180 to 275 kg
    396.48 to 605.73 lb
  • Average length
    190 cm
    74.80 in

Reproduction

Gestation period: 151 days

Number of young: 2-11 precocial piglets

Breeding season: February to April and August to October

Birthing: January to March and July to September

Weaning: 9 weeks

Sexual maturity: 18 months

Life span: up to 18 years, with 5 years being the average

Juveniles accompany their mother very soon after birth, but remain under cover in nests of tall grasses and branches for at least a week, walking beneath the mother while in the open. Females may disperse as yearlings while males may stay until secondary sexual characteristics have appeared (Estes 1991, d'Huart 1993). (d'Huart, 1993; Estes, 1991)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • Average number of offspring
    5
    AnAge
  • Average gestation period
    132 days
    AnAge
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    365 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    517 days
    AnAge

Lifespan/Longevity

Behavior

Forest hogs are shy creatures that live in low population densities and are therefore not well known. They are nocturnal and live in groups called 'sounders' which consist of 6-14 individuals in a 1:2 male:female ratio, led by a male. Subadult males form bachelor groups. The hogs tend to be more active, up to 10 hours per day, in areas where they are not hunted, and will range 8-12 km per day. They are most often out in the open during up to four hours of steady feeding between dusk and midnight. A range will consist of pastures, sleeping areas, water holes, wallows, rubbing places, latrines, and mineral licks, connected by paths through the underbrush. These suids scrape dirt from beneath logs or roots to bed down. Boars are intolerant of others, and will engage in one of two forms of fighting: snout pushing, a test of weight, or forehead ramming, which often fractures the skull. If cranial hollows meet exactly, this ramming behavior produces a loud report. A mating pair of hogs will leave a sounder, the male grunting loudly, and urinating frequently. The boar butts the female's hindquarters until she stands for copulation, which may last 10 minutes. Adults will surround piglets to defend them from their main predator, the hyena, and the leopard, which hunts them as well. Piglets will freeze at the sound of an alarm grunt. Forest hogs are extremely susceptible to hunting, because they come to bay and fight at the edge of cover (Estes 1991, d'Huart 1993).

Communication and Perception

Food Habits

Herbivore: The forest hog is unable to root like other Suidae, but it can dig quite well with its tusks for roots and minerals. Otherwise, the forest hog grazes on grasses, sedges and herbage. Sometimes, these suids will ingest carrion or eggs. They also practice coprophagy (Estes 1991, d'Huart 1993).

Economic Importance for Humans: Positive

The forest hog is an easy target for hunting, and although among some peoples of the Congo, the eating of H. mienertzhageni is considered to cause calamity, the species is hunted in much of its range, not only for subsistence, but for commercial meat markets. There is also some trade for the ivory of its tusks, and hides were sometimes used for leather. (d'Huart, 1993; Walker, 1968)

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

Economic Importance for Humans: Negative

The forest hog is a symptomless carrier of African Swine Fever (ASF), which is lethal to domestic pigs. This disease is transmitted by a tick called the tampan. These suids also can carry the trypanosomes for sleeping sickness (ngana) that is transmitted by the tse-tse fly to livestock and humans. They also transmit rinderpest and are responsible for significant crop damage (Macdonald 1995, d'Huart 1993).

Conservation Status

The forest hog is rated 3-4 by IUCN. This means that it has a restricted distribution, is threatened by habitat destruction, hunting pressure or other ecological pressure, however populations are not declining. The subspecies Hylochoerus mienertzhagheni mienertzhagheni has the smallest range, but appears to be relatively secure (Oliver 1993).

Contributors

Barbara Lundrigan (author), Michigan State University, Jennifer Bidlingmeyer (author), Michigan State University.

Glossary

Ethiopian

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

World Map

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

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.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

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.

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

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

tactile

uses touch to communicate

terrestrial

Living on the ground.

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.

References

Estes, R. 1991. Behavior Guide to African Mammals. Berkeley, Los Angeles, London: University of California Press.

Macdonald, D. 1995. The Encyclopedia of Mammals. London, Sydney: George Allen and Unwin.

Walker, E. 1968. Mammals of the World. Baltimore: Johns Hopkins Press.

d'Huart, J. 1993. 4.3 The Forest Hog (Hylochoerus meinertzhageni). Pp. 84-92 in W Oliver, ed. Pigs, Peccaries, and Hippos. Gland, Switzerland: IUCN.

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