The Visayan warty pig is a small, forest-dwelling pig, little known, and only recently recognized as a distinct species. The males or boars are much larger than the females or sows, and, unique amongst wild pigs, grow crests and manes during the breeding season that are as long as 23 cm. They are named after the islands where they live, and because of the three pairs of “warts” on the face of male pigs, which may help protect their face when fighting.
Found in the past throughout the Visayan Islands, which is the central archipelago in the Philippines, these pigs are now extinct in at least 98% of their former range, the few surviving populations concentrated in remaining habitat on the Negros and Panay islands of Negros. This species requires dense forested areas. In the past they occurred in primary and secondary forests at sea-level up to elevations of nearly a mile high, and also in grasslands.
There is little information about Visayan warty pigs in the wild. They live in social groups which are called sounders. An adult male with females and their young comprise a typical group. Family groups typically have three to six members, though they may have up to a dozen. Males may live on their own or in bachelor groups. This species lives a highly social life, usually foraging in family groups, communicating constantly with squeaks, grunts and chirrups. They are not territorial and have overlapping home ranges, sharing feeding, resting watering and wallowing areas. Their activity is nocturnal or crepuscular; they rest in hollows during the day.
Visayan warty pigs are omnivores but they mostly eat a wide variety of forest food: fruits, roots and tubers, and will sometimes plunder cultivated cereal and vegetable crops.
Little is known about the mating system in Visayans as there have been no detailed studies of their biology. It was only recently established as a separate species. After about 118 days of gestation, females exhibit nesting behavior. Their litters are usually two to four in number, the piglets being born in the dry season - January to March. A female can bear young every eight to twelve months. They carefully protect their piglets, which start eating solids at a week old and are weaned at about six months old. Juveniles gradually lose their stripes and after a year have adult coloration. Females are sexually mature when two or three years old, however, in captivity females can conceive as early as twelve months. Males are sexually mature at two years old.
The Visayan warty pig is extinct on 3 of the 6 main islands where it lived, and is in danger of disappearing from the fourth. Deforestation has been widespread, and so habitat loss is one of the major causes of the sharp decline in numbers, along with hunting. Interbreeding with domestic pigs is a further threat. They are also killed by local farmers, who seem them as pests; they are hunted extensively for local consumption, caught in wire snares and pitfall traps, and sometimes killed by explosive baiting devices that are buried in the ground, and are excavated when rooting.
No estimate of population size is available for this species. According to the Chester Zoo resource, 200 pigs only are thought to survive in the Philippines in their native habitat. Currently this species is classified as Critically Endangered (CR) on the IUCN Red List and its numbers continue to decrease.
Visayan warty pigs appear to play a major role in dispersing the seeds of some species of plants.