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LC - Desert warthog

Subspecies and Distribution (see map).

P. a. aethiopicus Pallas, 1766 – (extinct) formerly eastern Cape Province and upper Orange River, South Africa.

P. a. delamerei Lönnberg, 1909 – NW and 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 ca 1,400 m asl in Central Kenya. While thought to be restricted to arid environments, its range in Kenya has been found to extend southwards to Tsavo West National Park (W of Athi River and S of the Galana River). Formerly the species occurred in South Africa, in SE of the former Cape Province and apparently adjacent parts of KwaZulu-Natal, but it is now extinct there (see photo below).

Descriptive notes. No body measurement have been recorded for Desert Warthogs. External appearance is generally similar to Common Warthog P. africanus (see this species for general account) but slightly smaller in size and with less, shorter and lighter bristles. Depending on their environmental conditions, there can be striking body differences in fatness between Desert Warthog populations. The skin is usually light grey, but there is a wide variation of colour due to mud- and dust bathing. Morphological differences between Desert Warthogs and Common Warthog 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 round the eyes, and a shorter basi-occipital region that makes the head look “egg-shaped”, whereas it looks rather “diabolo-shaped” in africanus. The skull is similar in proportions to that of Common Warthog but diagnostically distinguished by other cranial and dental characters. Zygomatic arches are robust with large sinuses forming a spherical inflation of the jugal.

In the limited number of available samples of Desert Warthog skull lengths for the two sexes do not overlap, suggesting greater sexual dimorphism than in Common Warthog. Upper incisors are always absent. Lower incisors are absent or reduced to four or less, very small teeth, which hardly protrude from alveoli and are robably always concealed by gums. Third molars are also different: when all the enamel columns have come into wear, no roots have yet formed, unlike the condition in P. africanus. 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 both species in the shape of the canines: both lower and upper canines appear to be less curved in P. aethiopicus. The wear facet on the lower canine is differently placed, and the lower canines are less compressed. Dental formula: I 0/0-2, C 1/1, P 3/2, M 3/3 = 26–30. Chromosome number: unknown. DNA analysis has shown that aethiopicus and africanus belong to two genetically distinct lineages that diverged for approximately 4·5 million years ago, originating in the last part of the Pliocene.

Habitat. Desert Warthog is mainly a species of open arid regions. The distribution of the northern population lies within vegetation types of 'Somalia-Masai Acacia-Commiphora 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 altitudes, but none are above 1000 m. The species is dependent on the occurrence of water and shade and occupies regions with rainfall of 100–600 mm per year. Areas with higher rainfall are avoided as well as the driest and hottest desertic regions with rainfall less than 100 mm per year, corresponding with the hot coastal zone of Somalia, the eastern tip of Ogaden, and most of the sub-desertic shrubland east of Lake Turkana. The harsh climatic conditions associated with this vegetation type suggest that it could in fact be totally absent from a vast desertic area between Lake Turkana and the Lorian Swamps, in northeastern Kenya, as well as from the cross-border area between Kenya and Somalia, south of Mandera. In this sense Desert Warthog, albeit more specialised for extremely arid environments than Common Warthog, is not a true desert animal.

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

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

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 bring them close to human settlements, where they adapt their drinking routine to human water use patterns, and visit wells mainly in the morning, at day break and at sundown. In NE Kenya and Somaliland, local herders complain about their presence as warthogs interact with livestock for water availability and get occasionally aggressive, with reported cases of goat or sheep killing. Sometimes, large numbers of desert warthogs are present (over 100 per village), but sudden fluctuations in the resident population are observed, which raises the question of a possible migration pattern.

Breeding. Nothing is known.

Status and Conservation. CITES: not listed. Classified as Least Concern in The IUCN Red List. There are no major threats to the species. However, even if they live in Muslim-dominated areas, they may be subject to local incidence of hunting for bushmeat and ivory trade. Habitat degradation due to over-grazing 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.



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.

Bibliography.

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de Jong, Y.A., Culverwell, J. & Butynski, T.M.  (2009).  Desert warthog Phacochoerus aethiopicus found in Tsavo East National Park and Tsavo West National Park, southern Kenya.  Suiform Soundings 8: 4-6.

d’Huart, J.P. & Grubb, P.  (2001).  Distribution of the common warthog (Phacochoerus africanus) and the desert warthog (P. aethiopicus) in the Horn of Africa.  African Journal of Ecology 39: 156-169.

d'Huart, J.P. & Grubb, P.  (2005).  A photographic guide to the differences between the common warthog (Phacochoerus africanus) and the desert warthog (Ph. aethiopicus).  Suiform Soundings 5: 4-8.

De Jong, Y.A., Butynski, T.M. & d’Huart, J.P. (2016). Phacochoerus aethiopicus. The IUCN Red List of Threatened Species 2016: e.T41767A44140316. http://www.iucnredlist.org/details/full/41767/0 

Ewer, R.F.  (1957).  A collection of Phacochoerus aethiopicus teeth from the Kalkbank Middle Stone Age site, Central Transvaal. Paleontologia Africana 5: 5-20.

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).

Grubb, P. & d'Huart, J.P. (2013). Phacochoerus aethiopicus Desert Warthog; pp 51-53. in: Kingdon, J. & Hoffmann, M. (eds) 2013. Mammals of Africa: Volume VI. Pigs, Hippopotamuses, Chevrotain, Giraffes, Deer and Bovids. Bloomsbury Publishing, London.

Grubb, P. & Oliver, W.L.R.  (1991).  A forgotten warthog. Species 17: 61.

Lönnberg, E.  (1909).  Remarks on some wart-hog skulls in the British Museum. Proceedings of the Zoological Society of London 1908: 936-940.

Randi, E., d’Huart, J.P., Lucchini, V. & Aman, R.  (2002).  Evidence of two genetically deeply divergent species of warthog Phacochoerus africanus and P. aethiopicus (Artiodactyla: Suiformes) in East Africa. Mammalian Biology 67(2): 91-96.

Wilhelmi, F., Kaariye, X.Y. & Heckel, J.-O.  (2004).  The Desert warthog in the Ogaden, Ethiopia. Suiform Soundings 4(2): 52-54.