Sus cebifrons, Linnaeus, 1758

Don E. Wilson & Russell A. Mittermeier, 2011, Suidae, Handbook of the Mammals of the World – Volume 2 Hoofed Mammals, Barcelona: Lynx Edicions, pp. 248-291 : 283-284

9.

Visayan Warty Pig

Sus cebifrons

French: Sanglier des Visayas / German: \isayas-Pustelschwein / Spanish: Jabali de Bisayas

Taxonomy. Sus cebifrons Heude, 1888 ,

Cebu Island, Philippines.

This species was only upgraded to full species level in 1993. Before that it was variously classified as a subspecies of the Sulawesi Warty Pig (S. celebensis ), the Philippine Warty Pig (S. philippensis), or the Bearded Pig (S. barbatus ). However, two recent independent phylogenetic studies suggest that S. cebifrons is a sister species to all other members of the genus Sus and may be the most primitive member of the genus. Indications are that a split separating the Philippine species occurred very early in the evolution of the genus. Recent divergence estimates suggest that this happened sometime during the very late Pliocene or early to middle Pleistocene. This was a time of frequently alternating glacial cycles, and possibly pigs made it to what are now the Philippine Islands when sea levels were low enough to make dispersal by swimming or rafting possible. Two subspecies are recognized historically, but the nominate form cebifrons (Heude, 1888) from Cebu Island is extinct. Recent mtDNA studies have indicated the likely addition of a third subspecies from Panay; a fourth population from the remote island of Masbate is known only from a single specimen, which has yet to be formally described or compared to other populations. One extant subspecies is recognized.

Subspecies and Distribution.

S. c. megrinus Sanborn, 1952 — W Visayas (Negros, Panay, and possibly Masbate Is), Philippines.

Descriptive notes. Head-body ¢. 100 cm, tail 23 cm, shoulder height up to 63 cm (males) and 30-45 cm (females); weight 35-40 kg (males) and 20-35 kg (females), although weights of up to 80 kg have been reported from Negros. S. cebifronsis relatively small in size compared to other pig species. Males are much larger than females, with up to a fourfold difference in body weights between the sexes. The coat is generally gray-black in females and subadult males, but more fawn mixed with black in adult males. Both sexes have distinct manes extending from crest to hindquarters. Males in breeding condition develop even longer manes, which are grown and shed at the beginning and end of each breeding season (usually November to late March or early April). The mane is a very distinctive character of this species, often flopping over the face of the boar and obscuring the eyes, and extending back to the loins. Females have a weakly marked snout band; the band is very broad and well-marked white or whitish yellow in males. The generally distinct white snout band is a useful characteristic for distinguishing S. cebifrons from S. philippensis and Mindori Warty Pig (S. oliveri). The external appearance of S. oliveri is still poorly known, though S. cebifrons and S. philippensis may also be distinguished by the latter having more prominent white jowl tufts. The Palawan Bearded Pig (S. ahoenobarbus) also has a distinct white snout band, though this differs from S. cebifrons by typically extending downwards and backwards as a characteristic “white beard,” distinguishing this species from other Philippine wild pigs. S. cebifrons has a high-crowned, relatively small skull with obvious sexual dimorphism. Despite its common name Visayan Warty Pig, the facial warts of S. cebifrons are typically small, and these pigs completely lack gonial warts (warts on the angle of the jaw). The young of S. cebifrons are marked with wide, alternating orange-brown and black stripes that run from the shoulders to the rump. There are typically four black stripes. One pair runs down the back on either side of a paler dorsal stripe and another pair runs along the flanks and haunches. The juvenile striping loses definition at 7-9 months of age and adult coloration is fully achieved after one year. Animals from Panay seem to differ somewhat from those from Negros and Masbate. The Panay animals have grayer rather than predominantly black flank hair, a better developed mane that extends from the forehead down the back to the rump, and males have a more pronounced but narrower snout band. Females from Panay may have a mane, but it is less developed than in males. In animals from Negros, there is usually a dark reddish-brown or black tuft, with scattered red or straw-colored hairs, on the crown of the head. Other dental and cranial details also differentiate populations from Panay and Negros. The Negros animals appear to have a straighter skull profile with a more rounded crown, and the Cebu animals a more concave shape, although this observation was based on a very small sample.

Habitat. Originally this species occurred from primary and secondary forests at sea level to mossy forests at 1600 m of elevation, but with the loss of lower elevation forests, the warty pigs are now mostly confined to and isolated in the few remaining forested habitats at 800 m or above. Small numbers of these animals are also known to persist in some degraded habitats, such as Imperata cylindrica grasslands, as long as there are areas of dense cover, but there is evidence that some and perhaps most of these individuals are either feral domestic pigs or hybrids between S. cebifrons and free-ranging domestic pigs introduced by farmers in hinterland communities. In captivity, Visayan Warty Pigs readily bathe in open pools and use mud wallows, and it is assumed that the animals also do this in the wild state.

Food and Feeding. The Visayan Warty Pig is omnivorous, feeding on a range of plant and animal species. Because of the species’ scarcity in the wild there are no direct reports of feeding behavior, but some information has been obtained from scats and feeding signs. The species appears to feed on plant species such as Lithocarpus (Fagaceae) , Platea excelsa (Icainaceae), and Dillenia reifferscheidia ( Dilleniaceae ), with the former two species possibly being completely dependent on S. cebifrons for the dispersal of their seeds. The species also appears to feed on a range of vines, palms, wild bananas, and agricultural crops such as taro and avocados, as well as earthworms. Captive animals will readily consume a wide variety of cereals, fruits, vegetables, leafy branches, and grass, and most individuals will avidly consume rodents (rats and mice) and other prey items.

Breeding. The breeding behavior of S. cebifrons is primarily known from captive populations. The gestation period is about 118 days. One or two weeks prior to giving birth, females begin showing nesting behavior and may become aggressive to conspecifics. Females usually give birth overnight, and are very protective of their offspring. Litter size in the wild is between two and four, which is similar to those in captivity. A record number of five offspring in a litter was observed in two Philippine breeding centers in 2005; the piglets had to be weaned earlier than usual to help the female regain condition. Juvenile animals begin tasting solid food at one week of age and may be weaned by six months. Females are capable of producing a litter every 8-12 months. Females reach sexual maturity at an age of 2-3 years. Males may be sexually mature at two years, but do not possess the fully developed characteristics of adult males. Captive Visayan Warty Pigs can live up to 18 years.

Activity patterns. Little has been reported about the activity patterns of S. cebifrons in undisturbed areas, because these areas are so remote and the terrain so rugged as to make even chance observations unlikely. In more accessible areas, where the species is heavily hunted, the animals avoid human activity (but may raid agricultural crops planted within or close to forest edges) and are mainly active at night.

Movements, Home range and Social organization. This species is sociable, mostly living in small groups (though up to a dozen individuals have been reported). Considering its much reduced densities, larger groupings would likely form under more natural conditions. Animals in zoos are described as “playful and friendly,” which may be further reference to their social nature. The composition of S. cebifrons groups is typically a single adult male with several females (usually three or four, according to local hunters), plus young of both sexes. Solitary males have also been reported, but are encountered only rarely. Captive boars are routinely left with peri-natal sows. The sows vigorously defend their farrowing nests from intruding boars (and caretakers), but generally allow boars full access to infants within a few days of their first emergence from the nest.

Status and Conservation. Classified as Critically Endangered on The IUCN Red List. S. cebifrons is endemic to the West Visayas Islands of the central Philippines, where it is known or presumed to have occurred on all six main islands: Cebu, Negros, Guimaras, Panay, Masbate, and Ticao. Fragmented populations survive today on the islands of Negros and Panay. The species maystill occur on Masbate Island, although no confirmed sightings have been made since 1993; it was last reported on Cebu in the 1960s. It is extinct on Guimaras and Ticao. It is not known whether it or S. philippensis formerly occurred on the neighboring island of Siquijor, where wild pigs have been extirpated. S. cebifrons has been replaced by S. philippensis on Bohol and all other larger Philippine Islands east of Huxley’s Line except Mindoro, where it has been replaced by S. oliveri. It is thought to be extinct in over 98% of its former range and is now found only in small, fragmented populations. Besides the loss of suitable forest habitat, the species is highly threatened by hunting for food and to reduce crop raiding. Hybridization is another threat, there being recent evidence that warty pigs have bred with domestic pigs. This is obvious in animals killed by poachers, which with increasing frequency show evidence of hybridization, including shortened snouts, large ears, reduced manes, stockier bodies, and even piebald markings. In response to increasing evidence ofits critically threatened conservation status, in 1993 the IUCN/SSC Pigs, Peccaries and Hippos Specialist Group and other supporting partner agencies, including the Zoological Society of San Diego and the Rotterdam Zoo, devised and initiated a Visayan Warty Pig Conservation Programme under the auspices of a Memorandum of Agreement with the Philippine Government's Department of Environment & Natural Resources (DENR). Priority activities identified and implemented under the auspices of this agreement included various follow-up field status and ethnobiological surveys, education and awareness campaigns, development of new protected areas, and the establishment of properly structured conservation breeding programs. These include the development of scientifically managed wildlife rescue and breeding centers on Negros and Panay Islands and similar species recovery programs for a variety of other threatened taxa endemic to the West Visayas (e.g. the Visayan Spotted Deer, Rusa alfredi, and rufous-headed hornbill, Aceros waldeni). This was done partly with a view to reintroductions of these species, but also as a means of opportunistically acquiring sufficient numbers of founder individuals, by rescuing animals illegally caught in snares, confiscating live individuals offered for sale in local meat markets, and prevailing upon local owners to donate individuals they had acquired as pets from similar sources. In the case of the Visayan Warty Pig, there was also an urgent need to ensure the survival of pure-bred animals while the opportunity still existed to do so. Every attempt has been made to determine the precise origin and likely genetic purity of any such founder individuals, to ensure the likely purity of the separate stocks of these animals from Negros and Panay. This action was since vindicated by new evidence of important genetic differences between the Negros and Panay populations. First and second generation captive-bred animals from both islands have also been exported on breeding loans from the Philippine Government to the San Diego and Rotterdam Z00s, and are now being cooperatively managed in a number of approved breeding centers in the USA and Europe.

Bibliography. Cummings (2003), De Leon et al. (2008), Groves (1997), Groves & Grubb (1993), Hamann & Curio (1999), Huffman (2010), Kubbinga (2005), Lastimoza (2006), Oliver (1995, 2004, 2008, 2009), Oliver, Cox & Groves (1993), Pedregosa (2005), Rabor (1977).

Figures

On following pages 10 Phılıppıne Warty Pıg (Sus phı/ıppensıs) Mındoro Wany Png (Sus olıven) 12 Pılawın Bearded Pıg (Sus ıhoanobırbus). 13 Bearded Psg (Sus barbatus), 14 Sulawesı Wany Pug (Sus celebensıs) 15 Javan Wany Pıg (Sus venucosusl. 16 Eurasıan Wıld Pıg (Sus scrola) 17 Pygmy Hog (Porcııla salvımı)

Subspecies and Distribution. S. c. megrinus Sanborn, 1952 — W Visayas (Negros, Panay, and possibly Masbate Is), Philippines .