Warthog

The Warthog or Common Warthog (Phacochoerus africanus) is a wild member of the pig family that lives in grassland, savanna, and woodland in Sub-Saharan Africa. In the past it was commonly treated as a subspecies of P. aethiopicus, but today that scientific name is restricted to the Desert Warthog of northern Kenya, Somalia, and eastern Ethiopia.

The common name comes from the four large wart-like protrusions found on the head of the warthog, which serve the purpose of defence when males fight as well as a fat reserve.

Subspecies

 * Nolan Warthog (Phacochoerus africanus africanus) (Gmelin, 1788) – Burkina Faso, Ivory Coast, Democratic Republic of the Congo, Ethiopia, Ghana, Guinea-Bissau, Chad, Mauritania, Nigeria, Senegal, Sudan
 * Eritrean Warthog (Phacochoerus africanus aeliani) Cretzschmar, 1828 – Eritrea, Ethiopia, Djibouti, Somalia
 * Central African Warthog (Phacochoerus africanus massaicus) Lönnberg, 1908 – Kenya, Tanzania
 * Southern Warthog (Phacochoerus africanus sundevallii) Lönnberg, 1908 – Botswana, Namibia, South Africa, Zimbabwe

Description
Warthogs range in size from 0.91 to 1.5 m in length and 50 to 75 kg in weight. A warthog is identifiable by the two pairs of tusks protruding from the mouth and curving upwards. The lower pair, which is far shorter than the upper pair, becomes razor sharp by rubbing against the upper pair every time the mouth is opened and closed. The upper canine teeth can grow to 23 cm, and are of a squashed circle shape in cross section, almost rectangular, being about 4.5 cm deep and 2.5 cm wide. The tusk will curve 90 degrees or more from the root, and the tusk will not lie flat on a table, as it curves somewhat backwards as it grows. The tusks are used for digging, for combat with other hogs, and in defence against predators—the lower set can inflict severe wounds.

Warthog ivory is taken from the constantly growing canine teeth. The tusks, more often the upper set, are worked much in the way of elephant tusks with all designs scaled down. Tusks are carved predominantly for the tourist trade in East and Southern Africa.

The head of the warthog is large with a mane that goes down the spine to the middle of the back. There is sparse hair covering the body. Color is usually black or brown. Tails are long and end with a tuft of hair. Common warthogs do not have subcutaneous fat and the coat is sparse, making them suceptible to extreme environmental temperatures.

The male is called a boar, the female a sow, and the young piglets.

Ecology
The warthog is the only pig species that has adapted to grazing and savanna habitats. Its diet is omnivorous, composed of grasses, roots, berries and other fruits, bark, fungi, eggs and carrion. The diet is seasonably variable, depending on availability of different food items. During the wet seasons warthogs graze on short perennial grasses. During the dry seasons they subsist on bulbs, rhizomes and nutritious roots. Warthogs are powerful diggers, using both snout and feet. Whilst feeding, they often bend the front feet backwards and move around on the wrists. Calloused pads that protect the wrists during such movement, form quite early in the development of the fetus. Although they can dig their own burrows, they commonly occupy abandoned burrows of aardvarks or other animals. The warthog commonly reverses into burrows, with the head always facing the opening and ready to burst out if necessary. Warthogs will wallow in mud to cope with high temperatures and huddle together to cope with low temperatures.

Although capable of fighting, with males aggressively fighting each other during mating season, a primary defence is to flee by means of fast sprinting. The main warthog predators are humans, lions, leopards, crocodiles, and hyenas. Cheetahs are also capable of catching small warthogs. However, if a female warthog has any piglets to defend she will defend them very aggressively. Warthogs can inflict severe wounds on lions, sometimes ending with the lions bleeding to death. Warthogs have been observed allowing banded mongooses to groom them to remove ticks.

Social behavior and reproduction
Warthogs are not territorial but instead occupy a home range. Warthogs live in groups called sounders. Females live in sounders with their young and with other females. Females tend to stay in their natal groups while males leave but stay within the home range. Sub-adult males associate in bachelor groups but leave alone when they become adults. Adult males only join sounders that have estrous females. Warthogs have two facial glands; the tusk gland and the sebaceous gland. Warthogs of both sexes begin mark around six to seven months old. Males tend to mark more than females. Places that they mark include sleeping and feeding areas and waterholes. Warthogs use tusk marking for courtship and agonistic behaviors and to establish status.

Warthogs are seasonal breeders. Rutting begins in the late rains or early dry season and birthing begins near the start of the following rain season. The mating system is described as "overlap promiscuity". It is due to the males having ranges overlapping several females and the daily behavior of the female being unpredictable. Boars employ two mating strategies during the rut. With the "staying tactic", a boar will stay and defend certain females or a resource valuable to them. In the "roaming tactic" boars seek out estrous sows and compete for them. Boars will wait for sows to emerge outside their burrows. A dominant boar will displace any other boar that also try to court his female. When a sow leaves her den, the boar will try to demonstrate his dominance and then follow her before copulation. For the "staying tactic", monogamy, female-defense polygyny, or resource-defense polygyny is promoted while the "roaming tactic" promotes scramble-competition polygyny.

The typical gestation period is 5 or 6 months. When they are about to give birth, sows temporarily leave their families to farrow in a separate hole. The litter is 2 to 8 piglets, although 2 to 4 is more typical. The sow will stay in the hole for several weeks nursing her piglets. Warthogs have been observed to engage in allosucking. Sow will nurse foster piglets if they lose their own litter, making them cooperative breeders. Allosucking does not seem to be case of mistaken identity or milk theft. This may be a sign of kin altruism. Piglets are grazing at about 2–3 weeks and are weaned by six months. Warthogs are considered a "follower" species as the young are kept nearby at all times and do not hide.

Conservation status
The warthog population in southern Africa is estimated to be about 250,000. Typical densities range between 1 and 10 per km² in protected areas, but local densities of 77 per km² were found on short grass in Nakuru National Park. There are no current major threats. However, the species is very susceptible to drought and hunting, which may result in localized extinctions in South Africa. The Common Warthog is present in numerous protected areas across its extensive range.

Related species

 * Giant Warthog
 * Wild Boar