Potamochoerus porcus

8.

Red River Hog

Potamochoerus porcus

French: Potamocheére roux / German: Pinselohrschwein / Spanish: Potamocero rojo

Taxonomy. Sus porcus Linnaeus, 1766,

“Habitat in Africa” (= West Africa).

No subspecies have been designated, because no discernable geographically consistent morphological variation has been identified. Monotypic.

Distribution. Main tropical rainforest belt from Senegal and Guinea Bissau to NW Uganda and E DR Congo, reaching as S boundary N Angola (Cabinda); no recent records from Gambia or Chad and 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.

Descriptive notes. Head-body 100-145 cm,tail 30-45 cm, shoulder height 55-80 cm; weight 45-115 kg. Red River Hogs are the smallest and most colorful of all African pigs. They have short, laterally flattened bodies that are predominantly bright russet orange. There is a narrow white dorsal crest from the head to the tail, which is erected when the animal is excited. The pelage is short except for longer bristles on jaws and flanks. The head is strongly contrasted, with bold markings like a facial mask: grayish muzzle, white “brows” around the eyes, white cheeks and whiskers, and black marks on the snout, jaws, ears, and forehead. The ear pinnae 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. The tusks are small and sharp. Skull length is 32-:7-40. 5 cm (adult males) and 26.9-37. 8 cm (adult females). Dental formulais13/3,C1/1,P 4/3, M 3/3 (x2) = 42. Chromosome numberis 34. Life span is 10-15 years.

Habitat. Red River Hogs mainly occur in gallery forests and swamp margins of primary rainforest where there is significant vegetative cover. In transition zones, they frequently visit dry forests, savanna woodlands, and cultivated areas. The speciesis highly adaptable and locally benefits from regeneration of logged-over forested areas, where they find more varied food sources and a reduction of their natural predators. Population densities are 1-6 ind/km?, but wide variations are recorded. Up to 18-4 ind/km?* have been recorded in the forest-savanna ecotone of Lopé National Park, Gabon. The species is widespread in its habitat except where the Forest Hog (Hylochoerus meinertzhagent) is common.

Food and Feeding. 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 supplies. Seasonal aggregations of Red River Hogs at masting fruit trees account for observations of temporary groups of up to 60 individuals. In Makokou (Gabon), these groups are very noisy when breaking hard nutshells of Caula edulis and Irvingia gabonensis, which attracts the attention of predators and secondary feeders. The hogs are sometimes followed by guinea fowl, who peck about the turned over ground for food. Seasonal massive availability of preferred foods and the hogs’ high level of opportunism explain semi-nomadic circuits of movements.

Breeding. This species uses a wide range ofritualized postures with release of glandular secretions during male fights and rut. Sexual maturity is reached at 18-24 months. Gestation is 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 occurs at 2—4 months.

Activity patterns. These animals are most active in the evening and during the night, and rest in burrows deep within dense thickets during the day. They are capable of covering long distances in search of food, and like 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, the adult hogs 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 Leopards (Panthera pardus), but locally also Lions (P. leo), Spotted Hyenas (Crocuta crocuta), and pythons. Red River Hogs make up 20% of the biomass consumed by Leopards in Lopé National Park.

Movements, Home range and Social organization. In some areas, the narrow extent and linearity of the species’ home ranges (gallery forests in savanna habitats) may force frequent and extensive movements. Sounders roam a comparatively large home range, sometimes with over 4 km between resting and feeding areas. Distance covered daily is 3-6 km, depending on food availability and the presence of young. Red River Hogs are gregarious, with sounders of 6-20 females, subadults, and young attended by a large master boar. As with other suids, older juvenile males are bullied by their father if they approach his feeding or wallowing place too closely. On the move, hogs communicate by soft grunts in order to maintain the 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 oftrees.

Status and Conservation. Classified as Least Concern on The IUCN Red List as the speciesis relatively widespread and 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 in 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 with 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.

Bibliography. Dosimont (2004), Grubb (1993), Henschel et al. (2005), Kingdon (1997), Laurance et al. (2006), Okouyi (2002, 2006), Payne (2002), Querouil & Leus (2008), Tutin et al. (1997), Vercammen et al. (1993), van Vliet & Nasi (2008).