Warthog

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Warthog
Tarangire Warzenschwein1.jpg
At Tarangire National Park, Tanzania
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Suidae
Genus: Phacochoerus
Species: P. africanus
Binomial name
Phacochoerus africanus
(Gmelin, 1788)
Subspecies

4 sspp., see text

Distribution P. africanus.svg
  Distribution of the Common Warthog
  Possible range or accidental records

The warthog or common warthog (Phacochoerus africanus) is a wild member of the pig family (Suidae) found in grassland, savanna, and woodland in sub-Saharan Africa.[1][2] 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.[3]

The common name comes from the four large, wart-like protrusions found on the head of the warthog, which serve as a fat reserve and are used for defense when males fight. Afrikaans-speaking people call the animal vlakvark, meaning "pig of the plains".[4][5]

Subspecies[edit]

Description[edit]

Skull
P. a. massaicus, male, Serengeti, Tanzania

The warthog is medium-sized species; their head-and-body lengths range from 0.9 to 1.5 m (3.0 to 4.9 ft) and shoulder height is from 63.5 to 85 cm (25.0 to 33.5 in). Females, at 45 to 75 kg (99 to 165 lb), are typically a bit smaller and lighter in weight than males, at 60 to 150 kg (130 to 330 lb).[6][7] 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 25.5 cm (10.0 in) long, and are of a squashed circle shape in cross section, almost rectangular, being about 4.5 cm (1.8 in) deep and 2.5 cm (0.98 in) wide. A tusk will curve 90° or more from the root, and 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 defense 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 down the spine to the middle of the back.[6] Sparse hair covers the body. Its 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 susceptible to extreme environmental temperatures.[6]

Ecology[edit]

In Ngorongoro Crater, Tanzania
Feeding on its knees

The warthog is the only pig species that has adapted to grazing and savanna habitats.[8] Its diet is omnivorous, composed of grasses, roots, berries and other fruits, bark, fungi, insects, eggs and carrion.[9] The diet is seasonably variable, depending on availability of different food items. During the wet seasons, warthogs graze[8] on short perennial grasses.[10] During the dry seasons, they subsist on bulbs, rhizomes, and nutritious roots.[8][10] Warthogs are powerful diggers, using both their snouts and feet. Whilst feeding, they often bend their front feet backwards and move around on the wrists.[11] 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[10] or other animals. The warthog commonly reverses into burrows, with its head 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.[12]

Although capable of fighting (males aggressively fight each other during mating season) the warthog's primary defense is to flee by means of fast sprinting. The warthog's main predators are humans, lions, leopards, crocodiles, and hyenas. Cheetahs are also capable of catching warthogs of up to their own weight and raptors such as Verreaux's eagle owls and martial eagles sometimes prey on piglets.[13][14] However, if a female warthog has any piglets, she will defend them very aggressively. On occasion, warthogs have been observed charging and even wounding large predators. Warthogs have also been observed allowing banded mongooses to groom them to remove ticks.[15]

Social behavior and reproduction[edit]

Female with young, Serengeti National Park, Tanzania

Warthogs are not territorial, but instead occupy a home range.[16] Warthogs live in groups called sounders. Females live in sounders with their young and with other females.[9] Females tend to stay in their natal groups, while males leave, but stay within the home range.[9] Subadult males associate in bachelor groups, but leave alone when they become adults.[8] Adult males only join sounders with estrous females. Warthogs have two facial glands — the tusk gland and the sebaceous gland. Warthogs of both sexes begin to mark around six to seven months old.[17] Males tend to mark more than females.[17] They mark sleeping and feeding areas and waterholes.[17] Warthogs use tusk marking for courtship, for antagonistic behaviors, and to establish status.[17]

Warthogs are seasonal breeders.[8] Rutting begins in the late rainy or early dry season and birthing begins near the start of the following rainy season.[8] The mating system is described as "overlap promiscuity"; the males have ranges overlapping several female ranges, and the daily behavior of the female is 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.[18] In the "roaming tactic", boars seek out estrous sows and compete for them.[18] Boars will wait for sows to emerge outside their burrows.[8] A dominant boar will displace any other boar that also tries to court his female. When a sow leaves her den, the boar will try to demonstrate his dominance and then follow her before copulation.[8] For the "staying tactic", monogamy, female-defense polygyny, or resource-defense polygyny is promoted, while the "roaming tactic" promotes scramble-competition polygyny.[18]

The typical gestation period is five to six months. When they are about to give birth, sows temporarily leave their families to farrow in a separate hole.[8] The litter is 2-8 piglets, with 2-4 typical. The sow will stay in the hole for several weeks, nursing her piglets.[8] Warthog sows have been observed to nurse foster piglets if they lose their own litter.[19] This behavior, known as allosucking, makes them cooperative breeders. Allosucking does not seem to be a case of mistaken identity or milk theft,[19] and may be a sign of kin altruism. Piglets begin grazing at about two to three weeks and are weaned by six months.[8] Warthog young quickly attain mobility and stay close to their mothers for defense.[20]

Conservation status[edit]

The warthog population in southern Africa is estimated to be about 250,000.[21] Typical densities range between one and 10 per km2 in protected areas, but local densities of 77 per km2 were found on short grass in Nakuru National Park.[22] The species is susceptible to drought and hunting (especially with dogs), which may result in localized extinctions.[1] The common warthog is present in numerous protected areas across its extensive range.[1]

Related species[edit]

References[edit]

  1. ^ a b c d Cumming, D.H.M. (2008). Phacochoerus africanus. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 5 April 2009. Database entry includes a brief justification of why this species is of least concern.
  2. ^ Wilson, D. E.; Reeder, D. M., eds. (2005). Mammal Species of the World (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494. 
  3. ^ Wilson, D. E.; Reeder, D. M., eds. (2005). Mammal Species of the World (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494. 
  4. ^ Cahalane, Victor H. (1963). "Wart Hog". World Book Encyclopedia 19: 43. 
  5. ^ The -vark suffix is also used in the word "aardvark", whose name means "earth pig" in Afrikaans.
  6. ^ a b c Creel, Eileen (2005-03-11). "''Phacochoerus africanus'' common warthog". Animaldiversity.ummz.umich.edu. Retrieved 2013-07-30. 
  7. ^ "Common Warthog ''Phacochoerus africanus''" (PDF). Retrieved 2013-07-30. 
  8. ^ a b c d e f g h i j k Estes, R. (1991). The Behavior Guide to African Mammals, Including Hoofed Mammals, Carnivores, Primates. Los Angeles, University of California Press. pp. 218–221 ISBN 0520080858.
  9. ^ a b c Kleiman, D.G., Geist, V., McDade, M.C. (2004). Grzimek's Animal Life Encyclopedia, The Gale Group Inc.
  10. ^ a b c Kingdon, J. (1979). East African Mammals: An Atlas of Evolution in Africa, Volume 3, Part B: Large Mammals. Chicago, University of Chicago Press. pp. 231–249.
  11. ^ Unwin, Mike (2003). Southern African wildlife: a visitor's guide. Bradt Travel Guides. p. 68. ISBN 978-1-84162-060-2. 
  12. ^ Vercammen, P., Mason, D.R. "Pigs, Peccaries and Hippos Status Survey and Action Plan".
  13. ^ Martial Eagle Kills Baby Warthog |. Orion-hotels.net. Retrieved on 2012-08-22.
  14. ^ Owls of the World by Konig, Weick & Becking. Yale University Press (2009), ISBN 0300142277.
  15. ^ Warthog – Africa's Jester. Wildwatch.com. Retrieved on 2012-08-22.
  16. ^ Maher, C. R., Lott, D.F. (1995). "Definitions of territoriality used in the study of variation in vertebrate spacing systems". Animal Behaviour 49 (6): 1581. doi:10.1016/0003-3472(95)90080-2. 
  17. ^ a b c d Estes, R.D., Cumming, D., Hearn, G. (1982). "New Facial Gland in Domestic Pig and Warthog". Journal of Mammalogy 63 (4): 618–624. doi:10.2307/1380267. JSTOR 2462591. 
  18. ^ a b c Sandell, M., Liberg, O. (1992). "Roamers and Stayers: A Model on Male Mating Tactics and Mating Systems". The American Naturalist 139 (1): 177–189. doi:10.1086/285319. JSTOR 2462591. 
  19. ^ a b Jensen, S.P., Siefert, L., Okori, J.J.L., Clutlon-Brock, T.H. (1999). "Age Related Participation in Allosucking by Nursing Warthogs." Journal of Zoology London 248(4): 443–449
  20. ^ Walther, F. R. (1984). Communication and Expression in Hoofed Mammals. Bloomington, Indiana University Press ISBN 0253313805
  21. ^ Cumming, D. H. M. 1999. Study on the development of Transboundary Natural Resource Management Areas in Southern Africa – Environmental Context. Natural Resources, Land Use, and Conservation. Biodiversity Support Program. Washington, DC, USA.
  22. ^ Radke, R. 1991. "Monographie des warzenschweines (Phacochoerus aethiopicus)". Bongo, Berlin 18: 119–134.

External links[edit]