Phacochoerus aethiopicus, Pallas, 1766

Don E. Wilson & Russell A. Mittermeier, 2011, Suidae, Handbook of the Mammals of the World – Volume 2 Hoofed Mammals, Barcelona: Lynx Edicions, pp. 248-291 : 277-278

5.

Desert Warthog

Phacochoerus aethiopicus

French: Phacochére du désert / German: Wistenwarzenschwein / Spanish: Facocero de desierto

Taxonomy. Aper aethiopicus Pallas, 1766 ,

“Promontoria Bona Spei advectus,” between Kaffraria and Great Namaqualand ( South Africa, Eastern Cape Province), two hundred leagues from the Cape of Good Hope.

Nominate subspecies aethiopicus (Pallas, 1766) from eastern Cape Province and upper Orange River, South Africa, is extinct. Only one extant subspecies recognized.

Distribution. P. a. delamerei Lonnberg, 1909 — NW & S Somalia, E Ethiopia, and E Kenya. The distribution is insufficiently known but accurately recorded from several areas, including N Somalia (W Somaliland), S Somalia (Jubaland), E Ethiopia (Ogaden), and E Kenya, from near sea level to ¢. 1400 m in C Kenya. Although thought to be restricted to arid environments, its range in Kenya has been found to extend S to Tsavo West National Park (W of Athi River and S of the Galana River). Formerly the species occurred in South Africa, in the former Cape Province and apparently adjacent parts of KwaZulu-Natal, but it is now extinct there.

Descriptive notes. No body measurements have been recorded for Desert Warthogs. External appearance is generally similar to the Common Warthog (FP. africanus ), but the Desert Warthog is slightly smaller in size and with fewer, shorter, and paler bristles. Depending on environmental conditions, there can be striking differences in body fatness between Desert Warthog populations. The skin is usually pale gray, but there is a wide variation in color due to mudand dust-bathing. Morphological differences between Desert Warthogs and Common Warthogs have been overlooked until recently, which suggests that no strikingly different features distinguish them in the field. However, adult Desert Warthogs are characterized by hook-shaped or drooping genal warts, tips of ears that bend backwards (which gives the impression that their contour is angular), swollen suborbital pouches under the eyes, and a shorter basioccipital region, which makes the head look “egg-shaped.” The head looks rather “diaboloshaped” in the Common Warthog. The skull is similar in proportions to that of the Common Warthog, but diagnostically distinguished by other cranial and dental characters. Sphenoidal pits in the floor of the neurocranium on each side of the vomer are enormously enlarged and opened out, deepening the vomerine ridge. The zygomatic arches are robust, with large sinuses forming a spherical inflation of the jugal. In the limited number of samples of Desert Warthog skulls that are available, lengths for the two sexes do not overlap, suggesting greater sexual dimorphism than in the Common Warthog. The upper incisors are always absent. The lower incisors are absent or reduced to four or fewer and are very small: they hardly protrude from the alveoli and are probably always concealed by gums. The third molars are also different: when all the enamel columns have begun to wear, no roots have yet formed, unlike the condition in the Common Warthog. At this stage, all the columns are of about the same length and are able to continue growing, extending the life of the tooth. Differences were also recorded between the two species in the shape of the canines: both lower and upper canines appear to be less curved in the Desert Warthog. The wear facet on the lower canine is differently placed, and the lower canines are less compressed. Dental formulais10/0-2,C1/1,P 3/2, M 3/3 (x2) = 26-30. Chromosome numberis unknown. DNA analysis has shown that aethiopicus and africanus belong to two genetically distinct lineages that diverged approximately 4-5 million years ago, in the early Pliocene.

Habitat. The Desert Warthog is mainly a species of open arid regions. The distribution of the northern population lies within two vegetation types, “Somalia-Masai Acacia-Commuphora deciduous bushland and thicket” and “Somalia-Masai semi-desert grassland and shrubland.” These habitats range from xerophylous bush and open woodland to subdesert steppe. Desert Warthogs prefer plains on predominantly sandy soils, and avoid hilly terrain. Most records are from lowland areas below 200 m, a few are at higher elevations, but none are above 1000 m. The species is dependent on the availability of water and shade and occupies regions with rainfall of 100-600 mm per year. Areas with higher rainfall are avoided,as are the driest and hottest desert regions with rainfall less than 100 mm per year. Desert Warthogs are not present in the hot coastal zone of Somalia, the eastern tip of Ogaden, and most of the subdesert shrubland east of Lake Turkana. The harsh climatic conditions associated with this vegetation type suggest that the species could,in fact, be totally absent from a vast desert area between Lake Turkana and the Lorian Swamps in north-eastern Kenya. The Desert Warthog, albeit more specialized for extremely arid environments than the Common Warthog, is not a true desert animal.

Food and Feeding. With its peculiar incisor-less morphology and other cranial features, the Desert Warthog is the most specialized living suid. Its diet is not known, and nothing is known ofits feeding habits and physiology. As the incisors are functionally absent, the lips and gumsare used to detach or pick up food items. The rootless third molars suggest an adaptation toward an abrasive diet.

Breeding. Nothing is known.

Activity patterns. Little is known. The species seems most active during the day, even during the hottest hours. Family sounders spend the night in burrows. In the valleys of south Somalia, they raid crops seasonally and consequently are persecuted.

Movements, Home range and Social organization. Desert Warthogs are reported as locally abundant, living mostly near small and remote villages or lodges where there is water. In Ethiopia, they are common in Ogaden and can be observed both in family sounders in bushy areas and in larger aggregations of up to 30 individuals around permanent wells and close to towns. Their dependency on water brings them close to human settlements, where they adapt their drinking routine to human water use patterns, and visit wells mainly in the morning, at daybreak and at sundown. In north-east Kenya and Somaliland, local herders complain about their presence because the warthogs compete with livestock for water and occasionally become aggressive: they have been reported to kill goats and sheep. Sometimes large numbers of Desert Warthogs are present (over 100 per village), but sudden fluctuations in the warthog population occur, which raises the question of a possible migration pattern.

Status and Conservation. Classified as Least Concern on The IUCN Red List. There are no major threats to the species. However, evenif they live in Muslim-dominated areas, they may be subject to local hunting for bushmeat and trade in their ivory tusks. Habitat degradation due to overgrazing by domestic livestock and competition for water with humans and domestic livestock may be affecting populations of Desert Warthog in some regions, but this needs further investigation.

Bibliography. Culverwell et al. (2008), Ewer (1957), Grubb (1993), Grubb & d'Huart (In Press), Grubb & Oliver (1991), d'Huart & Grubb (2001, 2005), d'Huart et al. (2008), de Jong et al. (2009), Lonnberg (1909), Randi et al. (2002), Wilhelmi et al. (2004).

Figures

On following pages 2 Moluccan Babırusa (Babyrousa babyrussa) 3 Tog an Babırusa (Babyrousa rogeanensıs) 4 Common Warthog (Phacochoorus alncanus) 5 Desert Warthog (Phacochoerus aethıopıcus) 6 Forest Hog (Hylochoerus maınenzhagenı) Bushpıg (Pommochoeıus Iarvalusl 8 Red Rıver Hog (Poramochoerus porcas)

Distribution. P. a. delamerei Lonnberg, 1909 — NW & S Somalia , E Ethiopia , and E Kenya . The distribution is insufficiently known but accurately recorded from several areas, including N Somalia (W Somaliland), S Somalia (Jubaland), E Ethiopia (Ogaden), and E Kenya , from near sea level to ¢. 1400 m in C Kenya . Although thought to be restricted to arid environments, its range in Kenya has been found to extend S to Tsavo West National Park (W of Athi River and S of the Galana River). Formerly the species occurred in South Africa , in the former Cape Province and apparently adjacent parts of KwaZulu-Natal, but it is now extinct there.