Classification and Range
The Visayan warty pig belongs to the family Suidae. Suidae includes 19 species in six genera distributed throughout Europe, Asia and Africa. These Old World wild pigs, along with New World peccaries and formerly African hippos, made up the sub-order suina of even-toed ungulates. Suina are mostly omnivores with short legs, tusk-like canines and four toes in contrast to the more numerous species of long-legged, ruminant herbivores. Wild pigs in the New World and Australia, for example the Arkansas razorback, are introduced domesticated species that became feral.
The Visayan warty pig was endemic to six of the Visayan Islands in central Philippines; however, currently it exists in the western mountains of Panay and in scattered forests on Negros, and possibly Masbate. Its scientific name Sus cebifrons indicates Cebu Island plus frons probably from its distinctive frontal tuft. Negros and probably Panay have their own sub-species as did Cebu until its extinction in the 1990s. Despite its unique qualities, the Visayan only gained recognition as a separate species in 1997 according to IUCN Red List of Threatened Species).
Visayan warty pigs require dense forested areas. Formerly they inhabited primary and secondary forests from sea-level to elevations nearly a mile high, as well as grasslands. Unfortunately they lost over 95% of their former habitats especially in the lowlands. Today they live mostly above 2,600 feet (800 m) but can persist in degraded areas of invasive grasslands if dense cover exists.
Visayan warty pigs share characteristics typical in wild pigs. They possess medium-sized, barrel-shaped bodies and short legs. They have short necks, longish heads, small eyes, prominent snouts ending in a disk-like nose, and tusks which are upturned lower canines. Males generally have both larger tusks and warts than females and are much larger in size and weight.
Visayans possess distinctive features. Despite its common name, the Visayan warty pig has only small facial warts. The three pairs of fleshy warts are present only in males. Sparse bristles cover their bodies, dark gray or black in females and young males, and silvery or light-brown in adult males. Both sexes sport a tuft of dark reddish-brown or black hairs on the crowns of their heads. On Panay Island, breeding males annually grow this tuft into a long mane from forehead to rump. A white stripe running across the bridge of the nose and along the jaw provides another distinguishing feature of Visayans.
Head and body length: About 39 inches (100 cm)
Females: 12-18 inches (30-45 cm)
Males: up to 25 inches (63 cm)
Tail length: 9 inches (23 cm)
Females: 44-77 pounds (20-35 kg)
Males: 77-88, up to 176 pounds (35-40, up to 80 kg)
Believed to live from 10 -15 years in the wild.
In the wild: Omnivorous. Eats primarily earthworms, roots, tubers and fruits in the forest, but also agricultural crops.
At the zoo: Fruits and vegetables.
Reproduction - Mating in a Mohawk
For mating season, Visayan males acquire an impressive new hairdo. The already spiky head tuft grows into a long mane up to 9 inches long. When threatened, boars raise their manes and thus appear larger and more imposing. Combat between wild pigs involves slashing with tusks. Warts may help protect the face. Thickened skin and matted hair along the shoulders also offer protection. The chanting or courting boar nudges and sniffs females, does lateral displays, and rests his head on a sow’s rump. He continues until the receptive female stands for mating.
Near the end of the approximately 118 day gestation period, females exhibit nesting behavior. Sows farrow (give birth to a litter) usually during the night. The litters average two to four piglets. In the wild, native hunters report seeing piglets during the dry season from January to March. Sows carefully protect their piglets. The young have four wide, black stripes running from shoulder to rump. These alternate with orange-brown or lighter stripes. Piglets start eating solids when only a week old and wean around six months of age. Juveniles gradually lose the striping and acquire adult coloration after a year. Females may farrow every eight to twelve months.
Life Cycle - Living in a Sounder
Little is known about Visayans in the wild. Wild pigs live in social groups called sounders. A single adult male with sows and their offspring comprise a typical group of Visayans. Family groups commonly number between three to six members, but may be over one dozen. Males may live solitary lives or in bachelor groups. Females become sexually mature at two or three; however captive sows can conceive at twelve months old. Males take two years to acquire full adult boar characteristics.
Wild pigs live highly social lives. They usually forage in family groups accompanied by incessant communication in squeaks, chirrups and grunts. Wild pigs are not territorial since sounders have overlapping home ranges with shared feeding, watering, resting and wallowing areas. They are nocturnal or crepuscular and spend the day resting in hollows.
Location at the Zoo
Our Visayan warty pigs are located in the Tropical Asia biome across from the Elephant Pool. Another pig species, the African wart hog (Phacochoerus africannus), is exhibited near the lion exhibit overlook.
Visayan warty pigs are considered Critically Endangered by the International Union for the Conservation of Nature (IUCN) on its Red List. Current pure-bred Visayan population estimates do not exist. The population of Visayans is both extremely fragmented and declining. They are already extinct in over 95% of their former range.
Visayan warty pigs endure a vicious cycle in the wild. Visayans lost forest habitat to logging and cultivation of crops such as cane sugar. With the loss of traditional forest food sources, the wild pigs encroached on cultivated vegetable, fruit, sugar and cereal crops. Then they faced human persecution from farmers as crop-raiding pests. Contact with domesticated and feral pigs led to hybridization and spread of disease. Hunters kill them for their meat. It’s no wonder these natural seed dispersers of forest vegetation are highly endangered.
Conservation actions promote a future for the Visayan warty pig. Philippine law fully protects Visayans and some protected areas and natural parks exist on both Panay and Negros islands. However, enforcement has been poor and significant areas lack protected status. The Philippine Department of Environment and Natural Resources and San Diego Zoo cooperated in the formation of the Visayan Warty Pig Conservation Programme (VWPCP) in 1991/2. Its goals include surveys and field research, such as status of any Visayans on Masbate Island; local programs of education awareness, personnel training, and capacity-building; establishment of new protected areas; and conservation breeding programs of pure-bred animals both locally and internationally. A future goal includes recovery and reintroduction on Masbate and Cebu Islands, as well as Panay and Negros. Rotterdam Zoo’s breeding program focuses on the Visayan sub-species from Negros, while San Diego heads a similar program for the Panay Visayans.
Sources and Suggested Reading
“Animal Bytes: Wild Swine (Pigs, Hogs, & Boars)”. www.sandiegozoo.org/animalbytes/t-wild_swine.html
Oregon Zoo “Visayan warty pig fact sheet”. www.oregonzoo.org/Cards/VisayanWartyPig.htm
The Encyclopedia of Mammals, edited by Dr. David Macdonald. “Wild pigs and boars,” pp.500-503. 1999.
International Union for Conservation of Nature’s Red List. Sus cebifrons. www.iucnredlist.org/apps/redlist/details/21175/0
Encyclopedia of Life: Sus cebifron, Huede 1888. www.eol.org/pages/328323
Ulimate Ungulate. “Visayan warty pigs”www.ultimateungulate.com/Artiodactyla/Sus_cebifrons.html