Red river hog
Status: Least Concern
Did you know? Red river hogs are the smallest and most colourful of all African pigs.
Subspecies and distribution
No subspecies have been designated, because no discernable, geographical, consistent morphological variation has been identified. Monotypic.
The species occurs in the main tropical rainforest belt in Guinea Bissau, Senegal, Sierra Leone, Liberia, Ivory Coast, Ghana, through to Togo, Nigeria, Cameroon, Gabon, Republic of Congo, Angola (Cabinda), Central African Republic, Democratic Republic of Congo and NW Uganda. No recent records from Gambia or Chad. Its presence is uncertain in S Sudan and SW Ethiopia. As a species that may range widely through gallery forests, it may also occur in adjacent countries.
Head-body 100–145 cm, tail 30–45 cm, weight 45–115 kg. Red River Hogs are the smallest and most colorful of all African pigs. They have short, laterally flattened bodies predominantly color bright russet orange. There is a narrow white dorsal line between the head and tail, which is erected when the animal is excited. Fur is short except for longer bristles on jaws and flanks. The head is strongly contrasted with bold markings like a facial mask: greyish muzzle, white “brows” around the eyes, white cheeks and whiskers, and black marks on the snout, jaws, ears and forehead. Ear pinna have a prominent terminal tuft of white hair. Young Red River Hogs are dark brown with a facial mask and rows of pale yellow spots on body. Males have two humps on the muzzle in front of the eyes. Tusks are small and sharp. Skull length is between 327 and 405 mm (adult males) and from 269 to 378 mm (adult females). Dental formula: I 3/3, C 1/1, P 4/3, M 3/3 = 42. Chromosomes: 2n = 34. Lifespan: 10–15 years.
Red River Hogs mainly occur in gallery forests and swamp margins of primary rainforest, in portions with significant vegetative cover. In transition zones, they frequently visit dry forests, savanna woodlands and cultivated areas. The species is highly adaptable and locally benefits from regeneration of logged-over forested areas by the availability of more varied food sources and the reduction of their natural predators. Population densities range between 1 and 6/km² but wide variations are recorded, e.g., up to 18·4 animals/km² have been recorded in the forest – savanna ecotone of Lopé National Park, Gabon. The species is widespread in its habitat except where Forest Hog Hylochoerus meinertzhageni is common.
Red River Hogs have an omnivorous diet, with a marked preference for roots and tubers. They also feed on grasses, aquatic plants, bulbs, fruit, carrion, and various small animals. They use their snouts to root in the ground and can do serious damage to crops. The species uses the noises and calls of monkeys and frugivorous birds to detect potential food supplied. Seasonal aggregations of Red River Hogs for masting fruit trees account for observations of temporary groups of up to 60 individuals together. In Makokou (Gabon), these groups are known to be very noisy when breaking hard nutshells of Caula edulis and Irvingia gabonensis, which attract attention of predators and secondary feeders. They are sometimes followed by guinea fowls who peck about the turned over ground for food. Seasonal massive availability of preferred food and their high level of opportunism explain semi-nomadic circuits of movements.
The species is most active in the evening and during the night, and rests in a burrow deep within dense thickets during the day. It is capable of covering long distance in search of food, and likes to rest in wallows in shallow swamps. The whole sounder runs away when alarmed or frightened. If striped piglets are present, they crouch and freeze while adults face the danger. When cornered or wounded, they can display considerable courage and vigorously attack predators including humans. They are very good swimmers and are frequently seen crossing large rivers. Their main predators are humans and leopard, but locally also lion, spotted hyena, and python. Red River Hogs make up 20% of the biomass consumed by leopards in Lopé NP.
Movements, home range and social organisation
In some areas, the narrow extent and linearity of the species' home ranges (gallery forests in savana habitats) may force frequent and extensive movements. Sounders roam a comparatively large home range, sometimes with over 4 km between resting and feeding areas. Average distance covered daily is 3 to 6 km, depending on food availability and presence of young. Red River Hogs are gregarious, with sounders of 6–20 females, subadults and young attended by a large master boar. Like in other suids, older juvenile males are bullied by their father if they approach its feeding or wallowing place too closely. On the move, hogs communicate by soft grunts in order to keep cohesion of the sounder, and they use a wide range of vocalizations adapted to various circumstances. In shared home ranges, boars communicate their presence and status by frequent rubbing and tusking of trees.
This species uses a wide range of ritualized postures with release of glandular secretions during male fights and rut. Sexual maturity is reached at 18–24 months. Gestation: 120–127 days. Farrowing occurs in February/March in Nigeria and in December/January in Gabon, but females can give birth twice yearly in captive conditions. Litters of 1–4 piglets (rarely up to 6) are born in a sheltered hollow covered with a thick mattress of grasses and leaves, where they stay 10–15 days with their mother before joining the rest of the sounder. Weaning at 2–4 months.
Status and conservation
Not listed on CITES Appendices. Classified as Least Concern on The IUCN Red List as the species is relatively widespread, common, and there are no major threats believed to be resulting in a significant population decline.The main threat to this species is the growing pressure from hunting for commercial bushmeat trade and for subsistence. Together with the duikers, it is one of the most sought after and hunted species in the Congo Basin and it makes up 40% of the bushmeat sold on markets in Gabon. In the Congo Basin, the high demand for bushmeat and the spread of gun hunting are factors that can easily threaten the survival of this species. Experiments of raising in captivity have shown its susceptibility to stress during capture, low rate of survival of young (11–57%), but rapid adaptation to confined environment and human company.
Text adapted from: Meijaard, E., J. P. d'Huart, and W. L. R. Oliver. 2011. Family Suidae (Pigs). Pages 248-291 in D. E. Wilson, and R. A. Mittermeier, editors. Handbook of the Mammals of the World. Vol 2. Hoofed Mammals. Lynx Edicions, Barcelona, Spain.
Dosimont, O. (2004). Capture et élevage du potamochère (Potamochoerus porcus) en forêt équatoriale gabonaise. Game and Wildlife Science 21: 375-385.
Grubb, P. (1993). The Afrotropical Suids Phacochoerus, Hylochoerus, and Potamochoerus. Pp. 66-75 in Pigs, Peccaries, and Hippos. Status Survey and Conservation Action Plan, edited by W.L.R. Oliver. Gland, Switzerland: International Union for Conservation of Nature and Natural Resources (IUCN).
Henschel, P., Abernethy, K.A. & White, L.J.T. (2005). Leopard food habits in the Lope National Park, Gabon, Central Africa. African Journal of Ecology 43: 21-28.
Kingdon, J. (1997). The Kingdon Field Guide to African Mammals. London and New York: Academic Press and Natural World.
Laurance, W.F., Croes, B.M. , Tchignoumba, L., Lahm, S.A., Alonso, A. Lee, M.E., Campbell, P & Ondzeano, C. (2006). Impacts of roads and hunting on central African rainforest mammals. Cons. Biol. 20: 1251-1261.
Leus, K. & Vercammen, P. (2013). Potamochoerus porcus Red River Hog; pp 37-40. in: Kingdon, J. & Hoffmann, M. (eds) 2013. Mammals of Africa: Volume VI. Pigs, Hippopotamuses, Chevrotain, Giraffes, Deer and Bovids. Bloomsbury Publishing, London.
Okouyi, O.V.J. (2006). Savoirs locaux et outils modernes cynégétiques : développement de la filière commerciale de viande de brousse à Makokou (Gabon). Thèse de Géographie. Université d’Orléans.
Okouyi, O.V.J. (2002). Evaluation des impacts des activités humaines et du degré de péril de la biodiversité dans la Réserve de la Biosphère d’Ipassa-Makokou, Gabon. Report to MAB-UNESCO. 85pp.
Payne, A. (2002). Gestion de la ressource en viande de brousse au Gabon : exemple du potamochère (Potamochoerus porcus ) dans la région de Makokou. Thèse Ecole Nationale Vétérinaire d’Alfort.
Reyna, R., Jori, F., Querouil, S. & Leus, K. (2016). Potamochoerus porcus. The IUCN Red List of Threatened Species 2016: e.T41771A44141118. http://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T41771A44141118.en. Downloaded on 19 August 2016.
Tutin, C.E.G., White, L.J.T. & Mackangamissandzou, A. (1997). The use by rain forest mammals of natural forest fragments in an equatorial african savanna. Cons. Biol. 11: 1190-1203.
van Vliet, N. & Nasi, R. (2008). Hunting for Livelihood in Northeast Gabon: Patterns, Evolution, and Sustainability - art. no. 33. Ecology & Society 13: 33.
Vercammen, P., Seydack, A.H.W. & Oliver, W.L.R. (1993). The bush pigs (Potamochoerus porcus and P. larvatus). Pp. 93-101 in Pigs, Peccaries and Hippos: Status Survey and Action Plan, edited by W.L.R. Oliver. Gland, Switzerland: IUCN.