For most of the last century, African warthogs were considered a single species, Phacochoerus aethiopicus. It was only in the last decade that desert warthogs (Phacochoerus aethiopicus) and common warthogs (Phacochoerus africanus) were recognized as two distinct species. This recognition was based mainly on genetic evidence. As a result there is little specific research that has been done on the behavior, ecology, and life history of desert warthogs. Nearly all available information on warthogs, especially from prior to 2001, may or may not be applicable to what is now known as Phacochoerus aethiopicus. However, the two species are similar in appearance, ecological impact, and behavior and much of the above information is based on a combination of studies on both species of African warthogs. Information may change as further scientific research is completed.
Smell is the most important and keen sense that desert warthogs have. Much of warthog communication is though scent marking, through tusk and preorbital glands and urination. Males use urination to temporarily mark a burrow as his own. Sound is also very important, as they have a variety of warning calls used to alert the group to the presence of a predator. Because they have comparatively weaker sight, smell and hearing are the main ways by which desert warthogs are alerted to danger. Sight can be important in various social displays to signify dominance, submissiveness, or an imminent attack. Desert warthogs have a "strutting" behavior, consisting of walking deliberately around a more submissive warthog with the crest of hair and tail fully erect. Submissive displays include lying flat against the ground or even rolling over to expose the belly. Male warthogs fight to establish dominance, including pushing with the snout and horizontal strikes with tusks.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Desert warthogs are not considered threatened, as they have a large distribution and are adaptable. However, populations are considered in decline and face continued threats through human persecution in the form of hunting and competition for foraging habitat with domestic livestock. In areas where human persecution is intense many populations have become somewhat nocturnal- a change from their normal diurnal lifestyle.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
Warthogs can be agricultural pests, causing damage to bean, rice, or wheat fields. Their burrowing can cause problems for livestock or machinery. In the past warthog elimination campaigns were established to control warthogs as reservoirs for African swine fever, which can be transmitted to domesticated pigs. These campaigns are less common now as it is known that the disease is transmitted by ticks and thus removing the original wild host will do little to stop its spread. Rarely, and only when threatened, warthogs have attacked humans. This has lead to injury and, in a few cases, death.
Negative Impacts: crop pest; causes or carries domestic animal disease
Warthogs are iconic animals of the African savanna, so they can contribute to ecotourism. They also can be hunted and used as a source of food.
Positive Impacts: food ; ecotourism
All warthogs consume large amounts of grass and may influence plant communities through their foraging. Their ability to take and use the burrows of other animals (such as aardvarks) has a negative ecological impact on those species. Because they are a host for the tick Ornithodoros moubata, warthogs are a reservoir for African swine fever. They also serve as a preferred host for tsetse flies.
Commensal/Parasitic Species:
Warthogs are herbivores which feed mainly on grasses and roots. Because of their harsh environments, desert warthogs are probably less picky eaters than common warthogs, which tend to feed only on select plants. Warthogs eat a variety of grasses and shrubs, and occasionally fruits and some insects in hard times. An important element in their diet is underground rhizomes, bulbs, and tubers, all of which are dug up with the tusks and snout. They sometimes eat their own dung and the dung of other animals. During times of little food, they have been known to eat carrion. Plants eaten by warthogs include Sporobolus pellucida, Microchloa kunthii, Brachiaria, Cynodon dactylon, Chrysochloa orientalis, Bothriochloa, Cenchrus, Panicum maximum, Eragrostis tenuifolia, Harpachne schimperi, and Digitaria macrobole. They eat the fruit of Balanites, Sclerocarya, and Ficus species.
Animal Foods: carrion ; insects
Plant Foods: leaves; roots and tubers; wood, bark, or stems; fruit; flowers
Other Foods: dung
Primary Diet: herbivore (Folivore )
Desert warthogs are found in the Horn of Africa, in central and eastern Kenya, western Somalia, and southeastern Ethiopia. They were also known from South Africa, but are now extinct there.
Biogeographic Regions: ethiopian (Native )
Desert warthogs are primarily a savannah species, though they have higher tolerance for dry conditions than common warthogs, Phacochoerus africanus, and so can live in more arid and desert-like conditions. They generally stay away from heavily forested zones and areas with thick undergrowth. Most of their grazing area is at low elevations as they have a low tolerance to cold. Phacochoerus aethiopicus is currently a tropical species, though populations that are now extinct may have extended into temperate zones.
Range elevation: 0 to 1000 m.
Average elevation: 300 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland ; scrub forest
Warthogs have an average lifespan between 7 and 18 years. However, no study on lifespan has been done specifically on desert warthogs. Among juveniles, warthog mortality in the wild is about 50% per year, with adult mortality dropping to around 15% per year. The main limit on longevity in the wild is predation. Boars often have higher mortality rates than females due to a tendency to sleep out in the open (not in a burrow), especially during and after the mating season.
Typical lifespan
Status: wild: 7 to 18 years.
Average lifespan
Status: wild: 10 years.
At over 1 m long and generally more than 0.5 m tall at the shoulder, desert warthogs are large. They have a stocky build and a large, somewhat flattened head. There is significant sexual dimorphism, males are significantly larger than females. The characteristic "warts" that give Phacochoerus species their common name also differ between the sexes; males have much larger and more protrusive warts, which are paired masses of dense facial tissue. Males also have larger tusks (elongated canine teeth) than females. Juvenile desert warthogs are like adults, but smaller with much reduced "warts" and no tusks. Tusks gradually appear after the onset of puberty. Most desert warthogs are brown to dark brown with short and sparse hairs covering much of the body. A crest of much longer hair runs along the back of the neck of males and females. A portion of this crest is sometimes whitish in color.
The clearest morphological trait that separates desert warthogs from common warthogs (Phacochoerus africanus) is the lack of functional incisors. These two species are quite distinct genetically and common warthogs are usually slightly larger than desert warthogs. Desert warthogs are distinguishable from closely related bushpigs (Potamochoerus porcus) and giant hogs (Hylochoerus meinertzhageni) by their distinctive facial warts and larger tusks.
Range mass: 45 to 130 kg.
Average mass: 75 kg.
Range length: 100 to 145 cm.
Average length: 125 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; sexes shaped differently; ornamentation
The main predators of desert warthogs are large cats, including lions, leopards, and cheetahs. Hyaenas have also been known to hunt warthogs. Adult and juvenile warthogs run to the nearest burrow when threatened. All but the youngest individuals enter the hole tail-first, enabling them to use their tusks against the attacking predator. Though they can run at 55 km/hr, warthogs do not have the speed or endurance that many other prey animals have in sub-Saharan Africa, and so must get to a burrow as fast as possible. Lions pose an especially great threat to desert warthogs because they can dig warthogs out of their burrows. Desert warthogs have specific warning grunts and sounds that cause all members of a group to be on high alert. Juvenile warthogs, upon hearing a specific sound from the mother, will freeze in place then dash to the nearest burrow as fast as possible.
Known Predators:
During the mating period, female desert warthogs urinate quite frequently, up to 10 times more than males. Male warthogs can smell the urine from a significant distance and will investigate the urine to determine female reproductive state. During estrus females secrete a discharge from the vulva which changes the color of her hindquarters. The act of copulation lasts from 1 to 10 minutes, generally followed by the separation of the couple. Females and boars (males) mostly live in separate groups, but these groups interact more frequently and can even temporarily join in the mating season. Males and females may have several mates during a mating season, but females stop mating when they become pregnant.
Mating System: polygynandrous (promiscuous)
The timing of desert warthog mating is in part determined by climate. They inhabit areas with distinct dry and rainy seasons and tend to breed towards the end of the wet season (peaking around early April). Desert warthog females are polyestrous, with estrous periods lasting for about 72 hours and occurring once every 6 weeks (if her egg was not fertilized). Births occur between August and December, with most occurring in late September. Desert warthogs give birth to 2 to 3 offspring per year. Young emerge from the burrow to feed on grasses at about 3 weeks of age, though they are not fully weaned until they are about 6 months old. Offspring follow the mother wherever she goes, suckling as much as every 40 minutes, using her as shade from the hot sun, and sometimes using her feces as a food source. Desert warthogs are thought to become sexually mature slightly earlier than common warthogs, which mature at 1.5 years.
Breeding interval: Desert warthogs breed once yearly.
Breeding season: Desert warthogs breed from March to May, in general.
Range number of offspring: 1 to 8.
Average number of offspring: 2 to 3.
Range gestation period: 160 to 175 days.
Average gestation period: 170 days.
Range weaning age: 2.5 to 6 months.
Average weaning age: 3 months.
Range time to independence: 1.5 to 2 years.
Average time to independence: 2 years.
Range age at sexual or reproductive maturity (female): 1.0 to 1.5 years.
Range age at sexual or reproductive maturity (male): 1.0 to 1.5 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous
Because it takes desert warthog piglets over a year to fully mature, parental investment is significant. Males generally contribute very little to parenting as they more or less leave the group after mating season. Therefore, females must both provide food for the offspring as well as teach them how to find food and avoid predation. Also, because juveniles take so long to become independent, females may have two sets of young for a period of time, older young and newly born piglets. Birth takes place in a burrow, where females remain for long periods with newborns to nurse them for about a week. After that she will return often after short feeding periods for more nursing. Several months later, when offspring are ready for sustained excursions outside of burrows, the mother (along with other females in her group) must constantly be aware of predators and sound the alarm when one is spotted. Usually females will defend their young with great vigor, though there is a reported case of mothers standing idly by while a hyaena killed and ate a juvenile.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); post-independence association with parents; extended period of juvenile learning
The desert warthog (Phacochoerus aethiopicus) is a species of even-toed ungulate in the pig family (Suidae),[2] found in northern Kenya and Somalia, and possibly Djibouti, Eritrea, and Ethiopia. This is the range of the extant subspecies, commonly known as the Somali warthog (P. a. delamerei). Another subspecies, commonly known as the Cape warthog (P. a. aethiopicus), became extinct around 1865, but formerly occurred in South Africa.[1]
Fossils have been found from the Holocene epoch showing that two divergent lines of warthogs (Phacochoerus spp.) were in existence thousands of years ago. The ancestors of the present day common warthog (P. africanus) had a different number of incisors than the ancestors of the desert warthog (P. aethiopicus) line. During the late nineteenth century, P. aethiopicus became extinct in South Africa. Subsequently, study of mDNA as well as morphological analysis has shown that the East African population of warthogs, previously thought to be a variant of the common warthog, are in fact surviving members of the putatively extinct P. aethiopicus.[3]
The desert warthog is a stockily-built animal growing to an average length of 125 centimetres (49 in) and weight of 75 kilograms (165 lb) with males being larger than females. It has a rather flattened head with distinctive facial paired protuberances ("warts") and large curving canine teeth that protrude as tusks. These are not present in juveniles but grow over the course of a few years. They are larger in males than in females. The body is sparsely covered with bristly hairs and a more dense region of hairs runs along the spine and forms a crest. The tail is long and thin and is tipped with a small brush of coarse hair. The general colour is mid to dark brown but the crest is sometimes whitish. The desert warthog differs from the bushpig (Potamochoerus porcus) and the giant forest hog (Hylochoerus meinertzhageni) in having facial warts and proportionately larger tusks.[4]
Desert warthogs can be differentiated from the common warthog by their distinctive facial features, including curled back tips at the end of the ears, lack of incisors, and generally larger snout. The suborbital areas in desert warthogs are swollen in the form of pouches that often extend to the base of the genal warts; these same areas in common warthogs have no such pronounced swelling. The species also has more strongly hook-shaped "warts", a more egg-shaped head, thickened zygomatic arches, and enlarged sphenoidal pits. [5]
The desert warthog is native to the Horn of Africa. Its current range extends from southeastern Ethiopia through western Somalia to eastern and Central Kenya. The subspecies P. a. aethiopicus, commonly known as the Cape warthog, used to occur in the southeastern parts of Cape Province and the adjacent parts of Natal Province but became extinct around 1871. The habitat of the desert warthog is open arid countryside including thin woodland with scattered trees, xerophytic scrubland and sandy plains, but not upland areas. It needs regular access to waterholes and so may occur near villages and places where water seeps to the surface in otherwise dry areas.[1]
Desert warthogs live in social groups called "sounders" consisting mostly of females and their offspring while males tend to live in solitude or form bachelor groups. A sounder occupies a home range of about 10 square kilometres (3.9 sq mi) which is usually centred on a water hole. The warthogs dig a number of burrows, or take over holes excavated by other animals, and move from one to another. Where the ranges of two different groups overlap, each may use the same burrow on different occasions. The groups do not interact to any great extent.[4]
Desert warthogs are diurnal and are largely herbivorous. One of the older females leads the group and they forage for grasses, leafy plants, flowers and fruit. They dig up rhizomes, edible tubers and bulbs with their snouts and tusks and will eat insects when food is scarce, and even carrion. They sometimes eat dung, including their own, and will tear bark from trees.[4]
Females come into oestrus every six weeks in the breeding season, which usually coincides with the end of the rainy season between March and May. Their frequent urination leaves scent markers that inform males of their receptive state. The gestation period is about 170 days and a litter of usually two or three piglets is born in one of the burrows. The young begin to emerge from the burrow for short periods when about three weeks old and as they get bigger they follow their mother closely. They are weaned at three or more months but remain dependent on their mother for several more months after that. She defends them from predators such as lions, leopards, cheetahs and hyaenas. The desert warthog has specific warning grunts that alert the rest of the group to danger. They may freeze initially but then rely on their speed to escape. They can travel for short distances at 55 kilometres (34 mi) per hour as they run to the safety of one of their burrows. The young dive in head first but the older animals reverse direction and back in so that they can defend themselves with their tusks. The juveniles become sexually mature at one to one and a half years and life expectancy is ten or more years.[4]
Desert warthogs were experimentally infected with the virus that causes African swine fever. It was found that the warthogs showed no external signs of the infection but that they remained infective to domestic pigs for at least 33 days, this being the date on which the experiment terminated.[6] To reduce the risk of their animals being infected with this disease, farmers used to shoot desert warthogs. It is now realised that the disease is actually transmitted by the tick Ornithodoros moubata, and that elimination of warthogs in order to try to protect domestic swine serves no useful purpose.[4]
The desert warthog is an important host of the tsetse fly,[7][8] and in some parts of its range efforts are being made to reduce warthog numbers because of this.[8] Specifically, P. aethiopicus was the preferred host for Glossina swynnertoni and G. pallidipes in a study by Weitz 1963. These resulted in variously 16% or 12% (depending on sample) of P. aethiopicus infected with trypanosomes. The trypanosomes found included Trypanosoma brucei by Geigy et al 1967 and T. congolense by Baker 1968. In cases of per-acute infection, Ashcroft 1959 and Geigy found P. aethiopicus to be suffering widespread haemorrhaging of serous membranes of their vital organs, hepatomegaly, splenomegaly, lymphadenopathy, and body fat atrophy. Torr 1994 found that the presence of P. aethiopicus may be more or less of a problem, depending on whether their associated Glossina can be controlled, which varies widely with the availability of specific attractants.[7]
Warthogs are prolific breeders and research is being performed into their breeding and recruitment patterns as a means of deciding how best to control them.[8]
In its Red List of Endangered Species, the International Union for Conservation of Nature lists the desert warthog as being of "Least Concern". This is because it is common in some parts of its range and the population is thought to be stable. It occurs in a number of national parks and wildlife sanctuaries and it faces no significant threats although it may locally be hunted for bushmeat. It also faces competition at waterholes and for grazing with domestic livestock.[1]
The desert warthog (Phacochoerus aethiopicus) is a species of even-toed ungulate in the pig family (Suidae), found in northern Kenya and Somalia, and possibly Djibouti, Eritrea, and Ethiopia. This is the range of the extant subspecies, commonly known as the Somali warthog (P. a. delamerei). Another subspecies, commonly known as the Cape warthog (P. a. aethiopicus), became extinct around 1865, but formerly occurred in South Africa.
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