IUCN Conservation Status:

LR/lc = Lower Risk, least concerned.

Known for a distinct lack of beauty and its pennant tail, the warthog is unmistakable. Its name refers to the warts carried by the boar, while the Afrikaans name “vlakvark” refers to the animal’s habit of roaming plains along watercourses and marshlands. The warthog has an exceptionally high breeding rate that allows it to invade marginal and degraded habitats. It also contributes to the destruction of veld condition and damages fences by burrowing underneath to open escape pathways that are also used by game animals and domestic small stock.

Taxonomy

Classification

The Suidae family consists of five genera:

• Hylochoerus, the giant forest hog of western Africa
• Babyrousa, the Babirusa from Indonesia
• Potamochoerus, the bushpig of southern and central East Africa
• Sus, with 10 species and sub-species
• S. scrofa scrofa the Eurasian wild boar from the United Kingdom, New Guinea, Taiwan and Japan
• S.s. barbarus the Barbary wild boar from northern Africa
• S.s. cristatus the Indian wild boar from south-eastern Asia
• S. verrucosus the Javian wild boar from Java and the Philippines
• S. barbatus the bearded pig from Sumatra
• S. salvanius the pygmy hog from northern India
• S. scrofa the feral domestic pig from New Zealand, Australia and the USA
• Phacochoerus, the warthog P. africanus, formerly known as P. aethiopicus from sub-Saharan Africa, with 3 species and sub-species
• P. africanus africanus, the common warthog
• P.a. delamerei the desert warthog of central north-eastern Africa
• P. aethiopicus the extinct former desert warthog of southern and north-eastern Africa (became extinct with the rinderpest epidemic in 1896).

Description

A medium sized, pig-like animal with an enormous head, flattened above and with the lower part expanded forwards. Two pairs of tapered, warty growths composed of gristle without a supporting bone structure, occur along the sides of the face. The largest pair of warts are found only in boars and are up to 12 cm long, with a second pair, found in both sexes, growing only 3 cm long. Each cheek has a long flap of skin from the corner of the mouth, furnished with white whiskers. The body is sparsely covered with hair. A long mane of sparse, stiff hair growing from the back of the neck, continues halfway along the spine on the back. The adult sow is noticeably smaller than the boar. The tail is held perpenducular when running and alerted. Both the extinct warthog P. aethiopicus and the extant desert warthog P. africanus delamerei lack functional incisor teeth in the upper jaw. The common warthog has two in the upper jaw and 4-6 in the lower.

Comparison To Man

Trophy

Trophies consist of the ivory tusks formed from the upper canine teeth. These curve continuously down, turn out and then up to form a semi-circle, causing the lower canines to wear against them. The tusks of the boars are generally larger than that of the sow.

Habitat requirement

Warthogs are generally associated with sub-tropical, open, degraded grassland plains, flood plains, marshland areas and, more particularly, the ring-zone surrounding waterholes. They are also found in open savanna woodland and sparse shrubland, the new grass growth in burnt veld being a particular attraction. Shortgrass habitats with grasses of less than 15 cm that are associated with sweetveld habitat are preferred. A sourveld habitat is unsuitable. Warthog are fond of mud baths and prefer to be close to water sources. Thick bush, riverine thickets, forests and arid desert environments are avoided. Sub-arid environments are only suitable for the desert warthog and, even then, only marginally so. Warthog die easily during prolonged droughts due to the decline in the nutrient quality of dietary fodder.

Distribution

Feeding & Nutrition

Warthogs are omnivorous, feeding on vegetation, insects, maggots, rodents, bird nestlings, eggs and snakes. They also scavenge carcasses and bones. The greatest portion of the diet consists of sweet grasses and forb roots rather than the vegetative material found above-ground. Warthog kneel and dig out roots to a depth of 15 cm with their tusks and muscular snouts. This destructive behaviour results in the warthog being a high-impact species. Other food types include water sedges, dwarf shrubs, fruits, berries, soil and dung from other herbivorous animals. Wetland grasses are highly favoured. Warthog are highly selective feeders of both plant species and parts and require a diversity of grasses and forbs. Feeding exclusively takes place during daylight hours. At night they sleep in old burrows of the aardvark Orycteropus afer, and the porcupine Hystrix africanus.

Social structure

Pairs of warthog are solitary but temporary aggregations occur when 4-5 families meet to feed at the same site. Neighbouring families with overlapping home ranges are not aggressive but at dusk each family returns to its own den. Families consist of an adult boar, an adult sow and her offspring of the current season and sometimes those from the previous season. Piglets may stay with the family until an age of 27 months. Adult boars leave the family groups after the mating season and become solitary, occupying their own den but still sharing the same home range. Old post-mature adults of both sexes become solitary and occupy dens on the perimeter of the family home range.

Disease

Warthog are highly susceptible to swine-fever and mange and cannot tolerate malnutrition during droughts. It is the first game species to suffer high mortalities during these periods.

Information Table

Warthog information table
Characteristic		Boar	Sow
Adult body weight	kg	60-114 (mean 80)	45-75 (57)
Adult shoulder height	cm	68	60
Expected longevity	years	14-17	14-17
Age of sexual maturity	months	18	18
Age of social adulthood (1st mating)	months	30	18
Gestation	days		175
1st piglet born at	months		24
Furrow interval	months		10-12
Post maturity age (last mating)	years	10	13
Rutting season		May-Jun
Birth season:			Oct-Dec
Weaning age	months	3
Gender ratio: natural (all ages)		1	1.5
Gender ratio: production (all ages)		1	1
Mating ratio: natural (adults)		1	1
Mating ratio: production (adults)		1	1
Re-establishment: absolute minimum number needed		1	1
Re-establishment: smallest viable population size		2	2
Spatial behaviour: home range	ha	65-374	64-341
Spatial behaviour: territory range	ha	None	None
Large stock grazing init (adult): Dietary ratio (grass):	LSU	0.3 per animal (85% of diet)	0.21 per animal (85% of diet)
Browsing unit (adult): Dietary ratio: (browse):	BU	0.54 per animal (15% of diet)	0.49 per animal (15% of diet)
Maximum stocking load	140 animals per 1000 ha (at 450 mm annual rainfall)
Minimum habitat size required	ha	60
Annual population growth	65-120% (mean 75%)
Optimal annual rainfall	450 mm
Optimal vegetation structure: Grass height: Woody canopy cover:	0-15 cm 15-60%

Bibliography