The complex taxonomy of the wild pigs of the Philippines continues to be unravelled. The Philippine warty pig was originally described as a subspecies of the Sulawesi warty pig (Sus celebensis), then allied with the bearded pig (Sus barbatus) before being elevated to a full species in 1981 (including Sus oliveri, now considered to be a full species unto itself). Two subspecies are generally recognized: Sus philippensis philippensis from the Greater Luzon faunal region, and S. p. mindanensis from the Greater Mindanao faunal region. As-yet unpublished mitochondrial DNA studies suggest that these two subspecies may prove to be separate species. The karyotype is 2n = 36 chromosomes.

Head and body length: ~125 cm

Shoulder height: ~63cm

Tail length: ~12 cm

The Philippine warty pig is medium-sized among wild pigs in the Philippines - larger than the Visayan warty pig (Sus cebifrons) and smaller than the Palawan bearded pig (Sus ahoenobarbus) based on skull measurements. The overall coloration is black or dark brown, with sparse and bristly hair all over the body. Both sexes develop a crest of dark hair from the crown of the head onto their backs; this is especially prominent in mature males. The crest is black or greyish in S. p. philippensis and often flops forward over the face; in S. p. mindanensis, the crest is not directed forward, and it may include reddish or white hairs growing throughout. Males have two pairs of "warty" growths on the face: one pair in front of the eyes (preorbital warts), the other at the angle of the jaw (gonial warts). Females do not have these protuberances, but have a long, thin tuft of white hair where the gonial warts grow in males. Unlike the Visayan warty pig, there is generally no pale band across the snout (if present, it is thin and faint). Males have large canine tusks, which self-sharpen as the upper and lower teeth rub together.

Similar species

• More data is needed to definitively distinguish the Philippine warty pig from the Mindoro warty pig (Sus oliveri). Outwardly similar, their ranges are currently the best way to distinguish these two species.
• The Visayan warty pig (Sus cebifrons) is generally paler in color (grey rather than black in the Philippine warty pig) and has a distinct pale band across the snout. Males of both species develop impressive manes.

Gestation period: 116 days (101-130).

Litter size: Reports are highly varied, suggesting litter size of 2 (see photo above), or 3-4, or 5-8.

Anecdotal reports suggest that females seek sheltered spots, such as between buttreess roots of tall trees, to give birth. They may also gather grass and twigs to form a circular farrowing nest. Babies are marked with pale stripes typical of young pigs. One report suggests that births in the wild generally occur in April-May, although the captive-born striped young pictured above were photographed in January.

The Philippine warty pig is poorly known in the wild due to its skittish nature; most knowledge is based on anecdotes and scattered observations. Camera trap recordings indicate the Philippine warty pig may be active during both day and night, although in areas of human disturbance activity is mostly nocturnal. Physical evidence of this species' presence is more frequently seen than direct observations of animals themselves. Such signs include hoofprints and feces, mud wallows, areas where the soil has been plowed up while looking for roots, and nests of vegetation. Bark damage to trees has been attributed to male Philippine warty pigs rubbing them with their tusks, which may have scent-marking function. These pigs are considered agricultural pests and will raid crop fields (particularly seeking gabi, cassava, ubi, sweet potato, and young coconuts); damage is typically highest in April-May and October-November, when crops are ready for harvest. 

Family group: Solitary, in pairs, or in small family groups of 5-6 pigs (one adult male, a few adult females, and young). Historic records suggest group size up to 12.

Diet: Roots and tubers (this species will often raid crop fields), fallen fruit, leaves and grasses, and animal matter including invertebrates.

The Philippine warty pig is endemic to the eastern Philippines, where it formerly occured in a wide range of habitats, including grassland, primary forest, and secondary forest, from sea level to 2,800 m. It is now largely restricted to forests in fragmented, remote areas. Sus philippensis philippensis, from the Greater Luzon faunal region, is found on the islands of Luzon and Catanduanes. S. p. mindanensis, from the Greater Mindanao faunal region, is found on the islands of Mindanao, Basilan, Dinagat, Leyte, Biliran, and Samar. It is believed extirpated from Jolo and Marinduque. The approximate range is depicted in the map below.

IUCN Red List: Vulnerable (2017).

CITES Listing: Not listed (2024).

Threats: Habitat loss, overhunting, and hybridization with domestic swine. African Swine Fever is currently a major disease of concern.

Wild population numbers have not been assessed, but the Philippine warty pig has been extirpated from a large part of its historic range. This species is seen as an agricultural pest and is hunted as a result; unfortunately, increased deforestation increases the likelihood that these wild pigs will raid crops, leading to increased conflict with farmers.