Overview

Brief Summary

The largest of the wild pig species in the world, the giant forest hog (Hylochoerus meinertzhangeni) inhabits dense forested areas and open savannahs of western and central Africa, native to several countries including (but not limited to) Cameroon, Congo, Uganda, Ethiopia and Sudan. However, distribution can best be described as patchy due to deforestation and agricultural cultivation of the original habitat (d’Huart and Yohannes, 1995). Tectonic activity (e.g. the Rift Valley) is partially responsible for the evolution of 3 subspecies of the forest hogs, with H. m. meinertzhangeni, found in Ethiopia, being considered the ‘true’ giant forest hog (d’Huart and Yohannes, 1995).

Males reach a shoulder height of approximately 1 m and can weigh up to 275 kg; heavier than the females by roughly 50 kg. Their diet consists of sub-canopy vegetation, such as tubers, roots and underground meristems (Cerling et al. 2004). These hogs can be found in groups or as solitary animals, leaving clearly distinguishable tunnelling systems throughout the forest undergrowth (Treves et al. 2010). With an average lifespan of 5 years in the wild, forest hogs reproduce all year. Females are sexually mature after 1.5 years of age and produce a litter of 2-4 piglets after a 3 month gestation period.

Due to its aggressive nature and territoriality it has escaped the trappings of domestication and as a bonus is rarely hunted for bush meat (although still hunted as trophies) since their flesh has an unpleasant taste (Jori and Bastos, 2009; d’Huart and Klingel, 2008). Overall, very little scientific research has been done regarding their ecology and behaviour, but they are listed as Least Concern by the IUCN Red List of Threatened Species due to their large distribution range, relatively few threats and high numbers in the wild. 

  • d’Huart, J. P. and Yohannes, E. 1995. Assessment of the present distribution of the forest hog (Hylochoerus meinertzhangeni) in Ethiopia. J. Mt. Ecol. 3, 46-48.
  • Cerling, T. E., Hart, J. A. and Hart, T. B. 2004. Stable isotope ecology in the Ituri Forest. Oecologia, 138, 5-12.
  • d’Huart, J. P. and Klingel, H. 2008. Hylochoerus meinertzhangeni. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2.
  • Jori, F. and Bastos, A. D. S. 2009. Role of wild Suids in the epidemiology of African swine fever. EcoHealth, 6, 296-310.
  • Treves, A., Mwima, P., Plumptre, A. J. and Ioke, S. 2010. Camera-trapping forest-woodland wildlife of western Uganda reveals how gregariousness biases estimates of relative abundance and distribution. Biol. Conserv. 143, 521-528.
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Distribution

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.

Biogeographic Regions: ethiopian (Native )

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

The Forest Hog has a range similar in many respects to the Bongo Tragelaphus eurycerus, being distributed in scattered populations throughout undisturbed tracts of lowland rainforest in West Africa and on the right bank of the Congo River, and also present in highland mixed forests of the Albertine Rift, and in isolated montane forests in Kenya and Ethiopia (d'Huart and Kingdon in press). The species is believed to be extinct in Equatorial Guinea (Rio Muni), and there have been no records of Forest Hog from Rwanda since the late 1980s (B. Dowsett pers. comm.), though they may possibly survive in Nyungwe Forest (d'Huart and Kingdon in press).
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Physical Description

Morphology

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.

Range mass: 180 to 275 kg.

Average length: 190 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

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

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.

Range elevation: 3800 (high) m.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: savanna or grassland ; forest ; scrub forest

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Habitat and Ecology

Habitat and Ecology
Throughout its range, the Forest Hog inhabits a wide variety of forest types, ranging from subalpine areas and bamboo groves through montane to lowland and swamp forests, galleries, wooded savannas and post-cultivation thickets. It shows a preference for a convenient and permanent water source, thick understorey cover in some parts of the home range, and a diversity of vegetation types (d'Huart and Kingdon in press).

Adult size and sexual maturity are reached by both males and females at 18 months; life tables suggest an average life expectancy of 3.5 years and an average life span of five years, with a maximum of 18 years (d’Huart 1978).

Systems
  • Terrestrial
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Trophic Strategy

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).

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Life History and Behavior

Behavior

Perception Channels: tactile ; chemical

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Life Expectancy

Average lifespan

Status: captivity:
3.0 years.

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Lifespan, longevity, and ageing

Observations: Little is known about the longevity of these animals. They have been reported to live up to 18 years (Ronald Nowak 1999). Further studies in captivity are necessary, however, and maximum longevity could be underestimated.
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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).

Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual

Average birth mass: 1250 g.

Average gestation period: 132 days.

Average number of offspring: 5.

Average age at sexual or reproductive maturity (male)

Sex: male:
517 days.

Average age at sexual or reproductive maturity (female)

Sex: female:
365 days.

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

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).

IUCN Red List of Threatened Species: least concern

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
d'Huart, J.P. & Klingel, H.

Reviewer/s
Leus, K. ( Pig, Peccary & Hippo Red List Authority) & Hoffmann, M. (Global Mammal Assessment Team)

Contributor/s

Justification
Listed as Least Concern as the species is relatively widespread, sometimes locally abundant with a high reproductive potential, and, although it is subject to hunting in many parts of its range, it is not believed to be declining at a rate that would merit it being listed in Near Threatened or a threatened category.
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Population

Population
Generally occurs at low density over most of its range, but may be locally abundant and sometimes occurs at high densities. d'Huart (1978) recorded densities of 0.4/km² in Garamba National Park to 2.6 /km² in the central plain of Virunga National Park. On the Mweya Peninsula, Queen Elizabeth National Park, Uganda, density was reported as >10 km² in 1999. However, Klingel and Klingel (2004) subsequently recorded a 30% fall in the density mainly as a result of predation; this population had subsequently declined further and is now close to extinction (H. Klingel pers. comm. 2007).

Population Trend
Decreasing
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Threats

Major Threats
Forest Hogs are very vulnerable to deforestation and, to a lesser extent, to hunting for food. In some areas of the Congo Basin, Forest Hogs are avoided by shotgun hunters because their flesh is considered to have an unpleasant taste, but this is by no means a widespread aversion (d'Huart and Kingdon in press). Hogs are sometimes caught in snares and the meat is smoked to conceal its origin and sent to urban markets (R. Ruggiero, in d'Huart and Kingdon in press).
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Management

Conservation Actions

Conservation Actions
Forest Hogs occur in a number of protected areas, including: Sapo N.P. (Liberia); Taï N.P. (Côte d’Ivoire); Bia N.P. (Ghana); Minkebe N.P. (Gabon); Odzala N.P. (Congo Republic); the Sangha Tri-National complex (CAR, Congo, Cameroon); Maiko N.P., Virunga N.P. and Kahuzi-Biega N.P. (DR Congo); Ruwenzori N.P. and Queen Elizabeth N.P. (Uganda); Aberdares N.P. and Mt Kenya N.P. (Kenya); and Bale Mountains N.P. (Ethiopia).
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Relevance to Humans and Ecosystems

Benefits

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).

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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.

Positive Impacts: food ; body parts are source of valuable material

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Wikipedia

Giant forest hog

The giant forest hog (Hylochoerus meinertzhageni – the only member of its genus) is native to wooded habitats in Africa and generally is considered the largest wild member of the Suidae pig family; a few subspecies of the wild boar can reach an even larger size.[2] Despite its large size and relatively wide distribution, it was first described only in 1904. The specific name honours Richard Meinertzhagen, who shot the type specimen in Kenya and had it shipped to the Natural History Museum in England.[3]

Characteristics[edit]

Males reach up 2.1 m (6.9 ft) in length and 1.1 m (3.6 ft) in height, and may weigh as much as 275 kg (606 lb).[4][5] Females are smaller than males, and the eastern nominate subspecies is larger than H. m. rimator of Central Africa and H. m. ivoriensis of West Africa.[4] The giant forest hog has extensive hairs on its body, though these tend to become less pronounced as the animal ages. It is mostly black in colour on the surface, though hairs nearest the skin of the animal are a deep orange colour. Its ears are large and pointy, and the tusks are proportionally smaller than those of the warthogs, but bigger than those of the bushpig. Nevertheless, the tusks of a male may reach a length of 35 centimetres (14 in).[6]

Distribution[edit]

The skull of a male giant forest hog

Giant forest hogs occur in west and central Africa, where they are largely restricted to the Guinean and Congolian forests. They also occur more locally in humid highlands of the Rwenzori Mountains and as far east as Mount Kenya and the Ethiopian Highlands. They are mainly found in forest-grassland mosaics, but can also be seen in wooded savanna and subalpine habitats at altitudes up to 3,800 m (12,500 ft).[5] They are unable to cope with low humidity or prolonged exposure to the sun, resulting in them being absent from arid regions and habitats devoid of dense cover.[5]

Habits[edit]

The giant forest hog is mainly a herbivore, but also scavenges.[7] It is usually considered nocturnal, but in cold periods, it is more commonly seen during daylight hours, and it may be diurnal in regions where protected from humans.[4] They live in herds (sounders) of up to 20 animals consisting of females and their offspring, but usually also including a single old male.[4] Females leave the sounder before giving birth and return with the piglets about a week after parturition. All members of the sounder protect the piglets and they can nurse from all females.[6]

As all suids of Sub-Saharan Africa, the giant forest hog has not been domesticated, but it is easily tamed and has been considered to have potential for domestication.[4] In the wild, though, the giant forest hog is more feared than the red river hog and the bush pig (the two members of the genus Potamochoerus), as males sometimes attack without warning, possibly to protect their sounder.[4] It has also been known to drive spotted hyenas away from carcasses and fights among males resulting in the death of one of the participants are not uncommon.[6]

References[edit]

  1. ^ d'Huart, J.P. & Klingel, H. (2008). Hylochoerus meinertzhageni. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 5 April 2009. Database entry includes a brief justification of why this species is of least concern.
  2. ^ Meijaard, E., J.P. d'Huart, and W.L.R. Oliver (2011). Suidae (Pigs), pp. 248–291 in: Wilson, D.E., and R.A. Mittermeier, eds (2011). Handbook of the Mammals of the World, vol. 2. Hoofed Mammals. Lynx Edicions, Barcelona. ISBN 978-84-96553-77-4
  3. ^ Garfield, B. (2007). The Meinertzhagen Mystery: The Life and Legend of a Colossal Fraud. Potomac Books, Washington. Pp. 60. ISBN 1-59797-041-7
  4. ^ a b c d e f Novak, R. M. (editor) (1999). Walker's Mammals of the World. Vol. 2. 6th edition. Johns Hopkins University Press, Baltimore. pp. 1059–1060. ISBN 0-8018-5789-9
  5. ^ a b c Kingdon, J. (1997). The Kingdon Guide to African Mammals. Academic Press Limited, London. pp. 332–333. ISBN 0-12-408355-2
  6. ^ a b c Huffman, B. (2004). Giant forest hog. Ultimate Ungulates.
  7. ^ Dzanga Forest Elephants (2008). Departures and Arrivals.
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