Sus barbatus, Muller, 1838

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 : 285-286

13.

Bearded Pig

Sus barbatus

French: Sanglier barbu / German: Bartschwein / Spanish: Jabali barbudo

Taxonomy. Sus barbatus Muller, 1838 ,

Banjermasin, S. Kalimantan, Indonesia.

The seemingly absurd subspecific name 0: has been commented on by several authors. Apparently the name was split from a Sumatran tribal name for pig “nangoi,” with only the last bit of the word used. Two subspecies are recognized.

Subspecies and Distribution.

S. b. barbatusMuller, 1838 — BorneoandassociatedIs, possiblyextendingtoTawiTawi. S. b. oi Miller, 1902 — Peninsular Malaysia, Sumatra, and Bangka.

Descriptive notes. Head—body 137-152 cm (males, although some reports suggest that males can attain a total length of 208 cm) and 122-148 cm (females), tail 17-26 cm, shoulder height 90 cm, hindfoot 27-32 cm; weight usually ranges from 58 kg to 83 kg, with females somewhat lighter than males. When food is abundant, weights of up to 200 kg can be attained. Adult Bearded Pigs are characterized by their relatively large body size, reduced sexual dimorphism compared to other species of Sus , long legs, a bearded jaw tuft, and sparse body hair. The species has smaller warts and a more elongated skull than the other warty pigs, relatively small ears, and a long tail with a large terminal tuft divided into distinct anterior and posterior parts. The head is typically long, with a beard of bristles extending along the lower mandibles and a thick band of forward-pointing bristles across the snout above the mouth. The nominate subspecies barbatus has long, sweeping cheek whiskers and thicker and longer hairs on the snout band (especially in males); the whiskers of the subspecies oi are shorter on the cheeks, but long and wiry over the snout. It has been suggested that the body of oi is flatter bilaterally than that of barbatus , but this has not been confirmed. The overall body coloration of Bearded Pigs varies from blackish in young pigs to a paler reddish brown, yellow-gray, or almost buffy white in adults. The color of mud wallows affects the apparent color of pigs. Piglets of the Bearded Pig are longitudinally striped, black-brown and whitish to fawn; these stripes are lost by six months of age. Females have six pairs of mammae.

Habitat. Bearded Pigs are well adapted to the extensive dipterocarp forests of Borneo, Peninsular Malaysia, and Sumatra. This tree family is often dominant in lowland and hill forests, and is characterized by synchronized flowering and mast-fruiting. Bearded Pigs also make extensive use of riverbanks, where they root among herbs and look for earthworms. Other habitats they use include estuarine swamps, secondary and all kinds of oldjungle, beaches, all kinds of plantations, clearings, and also the outskirts of towns. The species is well known forits migratory behavior. Bearded Pigs are scattered across large regions during non-mast fruiting times, but move from both mountain and swamp habitats to drier lowland forests when fruit becomes abundant.

Food and Feeding. Bearded Pigs are real omnivores and it has been said that “it is almost easier to state what they will not eat.” They feed on a long list of food plants, but also consume roots, fungi, invertebrates in soil and rotting wood, small vertebrates, turtle eggs, and carrion. Fruit supply is believed to have particular influence in determining growth rate, fat deposition, and reproduction. The other foods that normally occur in the forest are assumed to allow only slow growth at best. The oil-rich seeds of members of the tree families Fagaceae and Dipterocarpaceae are thought to be especially important. During mast fruiting the majority of seeds in the diet are dipterocarps, although they can and will eat other species. Oaks, especially Castinopsis spp., Lithocarpus spp. , and Quercus spp. , are also favorites. During fruiting times, they are almost solely seed predators, and Bearded Pigs play an important role in the distribution of seeds. They also consume a few figs (e.g. Ficus dubia), melastomes, and other tiny, hard testas, which can pass through their guts and germinate.

Breeding. Age at first pregnancy varies in the wild from about 10 to 20 months. The rut appears to coincide with synchronized flowering in the forest, occuring during the transition between late flowering and early fruit formation. Falling petals therefore offer observers a potential visual cue. During the onset of droughts and related flowering of dipterocarps, male Bearded Pigs rut and females construct nests. In big fruiting years, Bearded Pigs can “double-clutch.” This suggests that a certain nutritional status may have to be attained by females before they are receptive to mating. Pregnant females had a median fatness index (finger-widths of fat depth at the shoulder) of 1-5, whereas rutting males scored zero on this measure (n = 19). Gestation length is estimated at 90-120 days, based on the interval between rut and the ensuing birth-peak. Births occur in a nest, which is constructed of vegetation by the mother, and which is occupied by her and the new piglets for a week or so. Data from hunter interviews indicated that the median number of piglets accompanying an adult female was seven (n = 53), which was the same as the median number of fetuses counted in dead females (n = 8). Litter size is, however, very variable in part because of the influence of female size; small mothers typically have 3—4 piglets in a litter and large ones have 10-12.

Activity patterns. Bearded Pigs are mostly diurnal. They are subject to irregular migrations, seeming to follow fruit when in season so that one year a particular spot may swarm with them but not be troubled again for many years after. The ripening of illipe nuts ( Shorea sp. ) in Sarawak and East Kalimantan appears to be significantly correlated with pig migrations. These mass migrations of Bearded Pigs are distinct from annual local movements damaging rice fields. The somewhat forced, lemminglike aspects of these large scale pig migrations are exemplified by the observation of a pig whose hindquarters were paralyzed and which pulled itself forward byits front legs to follow its conspecifics. The appearance of large numbers of pigs traveling together is especially obvious during river crossings, which they do in groups of over 100 animals. This provides local hunters with the opportunity to kill large numbers of pigs for meat and fat, from which they extract oils. Mass river crossings might have evolved at a time when crocodiles were still abundant in the region. Bearded Pigs appear to exist in different population states, which have been summarized as follows. 1) Dispersed,static populations exploiting small, dispersed, unpredictable and discontinuous “background” food sources. Low breeding and growth rates possible. Local movements only. Example: typical mixed dipterocarp forest in Borneo between generalized fruiting episodes. 2) Small to medium populations exploiting concentrated, predictable and continuous “target” food sources. High breeding and growth rates possible. Local movement only. Example: Koompassia-Burseraceae forest in Peninsular Malaysia. 3) Small to medium populations, with members aggregating to exploit large, dispersed, unpredictable food sources. Breeding and birth rates depend on success of matching movements to fruiting within a dynamic mosaic of fruit production. Short to medium-range movements. Example: typical mixed dipterocarp forest in Borneo between generalized fruiting episodes. 4) Small to large populations moving regularly to exploit concentrated, predictable, and discontinuous target food sources. Breeding and growth linked to activity of food sources. Short-range to long-range movements. Size of population varies from year to year depending on background food supply. Examples: Dryobalanops aromatica association in Peninsular Malaysia; Dinochloa association in Sabah. 5) Large and expanding population exploiting an exceptional supply of background food available over a period sufficient for severallitters to be raised to sexual maturity. High breeding and growth rates characteristic. Long range movements. Example: interior of Sarawak in 1954, 1959, 1983 and 1987. 6) Very large and collapsing population having exceeded background food supply. Low breeding and high death rates. Increasingly desperate long-range movements. Example: starving herds reported from Malaya and Borneo. It remains largely unstudied how these different population states have been affected by the continuing loss, degradation, and fragmentation of forest habitats. Unconfirmed information from local people in Kalimantan and Sarawak suggests that mass migrations of pigs no longer occur to the same extent as reported formerly, even as recently as the 1980s and early 1990s, which might indicate that with the removal of millions of hectares of high timber value dipterocarp forests food dynamics and related population states have been severely disrupted.

Movements, Home range and Social organization. The basic social unit is that of a female and her litter. These units often join up, and much larger aggregations are formed occasionally, with scores or even hundreds of pigs traveling together. Fully adult males seldom associate with the natal groups. The pigs’ movements vary so much throughout the year and between years that no reliable home range estimates can be made unless animals are radio-tracked for several years. Such studies have recently been completed in Sabah, Malaysia, but the data are not yet available. Bearded Pigs are powerful swimmers and easily cross the many large rivers of Borneo and Sumatra. They have also been reported to cross seas, which might explain why they occur on so many small islands. A report from the 19" century mentions droves of pigs swimming across the Klumpang Bay in west Borneo, a distance of about 8 km. There are numerous, apparently reliable, accounts of wild pigs crossing the sea channel between Sabah and Sibutu (a distance of some 45 km), and also the Kowie harbor near Tawau, which is at least 9 km. A Bearded Pig was found swimming in the middle of the Sandakan Bay in Sabah, apparently trying to swim from Pulau Bai to the Sandakan side of the bay, 5 km away.

Status and Conservation. Classified as Vulnerable on The IUCN Red List, mostly because of the rapid loss of its forest habitat and high hunting pressure throughoutits range. The Bearded Pig occurs in Peninsular Malaysia, Sumatra, and on Borneo. It is also reported from the island of Sibutu, west of the Sulu Archipelago in the Philippines, and possibly on Tawi Tawi Island. In Peninsular Malaysia and Sumatra its distribution is now limited to a relatively small part ofits presumed prehistoric range. In Borneo the species is still widespread but likely declining. There are additional records from a range of smaller islands, where the status of the speciesis unclear but populations have possibly been extirpated. This includes the islands of Balembangan, Banggi, Batam, Bauwal, Bintan, Bruit, Bunju, Burung, Durian Besar, Galang, Jambongan, Juanata, Karimata, Kundur, Lamukotan, Laut, Malawali, Mapor, Miang Besar, Molleangen, Panebangan, Pelapis, Ransang, Rempang, Rupat, Sauh, Sebuku, Sibutu, Tarakan, Tebing Tinggi, and Ungar. Humans have lived in Borneo for at least 40,000 years and have been hunting mammals such as Bearded Pigs for at least 35,000 years. Holocene and prehistoric cave finds in Sabah, Sarawak, and East Kalimantan indicate that Bearded Pigs have been the most commonly hunted Bornean mammal for at least the last 15,000 years. The archaeological evidence suggests that the Bearded Pig was hunted but was apparently fairly plentiful and widespread in the Malaysian Peninsula and Sumatra about 1500-2000 years ago. Overhunting has since led to population declines. In some parts of Malaysia, Sumatra, and Borneo, Bearded Pigs had already been hunted to near extinction by the 1920s. More recently, the threat of extinction is becoming a reality in many more parts of their range, where overhunting, logging, and conversion of forests have caused a rapid decline in Bearded Pig populations. Overhunting has also likely led to the extermination of many small-island populations. In 1906, such extinctions were reported for the Penata and Kebun Islands in the Burung group of northern West Kalimantan, and presumably extinctions have also occurred in the often densely settled islands where Bearded Pigs used to occur. It has been estimated that hunters in Sarawak take an annual harvest of up to one million or more pigs, making wild pork meat of considerable economic significance. This is quite often related to commercial timber extraction. One typical logging camp in Sarawak killed as many as 880 pigs per year, mainly for food. Hunting in these camps was found to be wasteful, with pigs being killed on sight even if the worker did not need the meat. In one logging area, for example, during a pig migration, people would kill an animal, take only the prime cuts of meat, leave the rest to rot, and kill another animal the next day. Bearded Pigs are by far the most preferred species of wild meat throughout Sarawak and Sabah, where they comprise as much as 72% of the dressed weight of all animals hunted. In these areas, the impact of hunting seems clear, with a significant correlation between hunting pressure and animal density. This pattern is so strong that hunting pressure overrides the large effects of habitat variables and is the single main determinant of animal density in an area. As hunting pressure increases, the density of all animal groups investigated, including Bearded Pigs, decreases, until all large animals are locally extirpated. This pattern of high hunting pressure on these animals is also found among Penan and Kenyah tribes in East Kalimantan, where pigs contributed 79-8% of all catches and 91% ofall the edible meat. On average these people consume of 133-6 kg of pig meat per person per year. The estimate for Sarawak is 12 kg of pig meat per person per year. In Peninsular Malaysia, the more sedentary population of Bearded Pigs, apparently associated with continuously fruiting Koompassia-Burseraceae forests, is endangered by hunting as well as habitat destruction. The habitat changes experienced on the peninsula since the Second World War have almost certainly favored Indonesian Banded Pigs (S. scrofa vittatus) over Bearded Pigs in those parts of Peninsular Malaysia and Sumatra where sympatry between these species occurs. This poses a further, and potentially serious, threat to Bearded Pigs. Available data indicate that wherever these two species are sympatric, the number of Eurasian Wild Pigs is greater than the number of Bearded Pigs, and that the Eurasian Wild Pig now has a much wider range of distribution than the Bearded Pig throughout these regions. In Sumatra, habitat disturbance has been at least as extensive as in Malaya. A comparison between the current distribution of Bearded Pigs and that of the remaining native forest supports the contention that the species cannot long survive the reduction and fragmentation of these habitats. The same situation probably applies to Bangka and the Riau Archipelago, where habitat disturbance has been at least as extensive as in Sumatra, and where the continued survival of the species is not clear. These animals are also potentially threatened by various contagious diseases. For example, a rinderpest epidemic that killed a large proportion of the domestic cattle population of south-east Borneo between 1871 and 1872 evidently spread to both domestic pigs and Bearded Pig populations over large parts of Borneo. Several similar and successive outbreaks of rinderpest in domestic cattle between 1878 and 1894 also killed off large numbers of these animals. The most serious may have been an epidemic in 1894, when populations of Bearded Pigs had already been severely reduced by epidemics in central Borneo in 1888 and 1889. A final epidemic occurred in 1906, when a great many Bearded Pigs succumbed to a contagious disease in the Tabalung area in South Kalimantan. There are no recent records of such epidemics, but the proximity of domestic animals to remaining Bearded Pig populations is a potentially serious threat, particularly at times when the pigs may already be nutritionally stressed.

Bibliography. Banks (1931), Barton et al. (2009), Bennett et al. (2000), Boden Kloss (1905), Caldecott (1988, 1991a, 1991b), Caldecott & Caldecott (1985), Caldecott, Blouch et al. (1993), Chin (2001), Cranbrook & Labang (2003), Curran & Leighton (2000), Curran & Webb (2000), Genov (2004), Hancock et al. (2004, 2006), Ickes (2001), Ickes & DeWalt (1999), Kawanishi, Gumal & Oliver (2008), Kawanishi, Richardson & Lazarus (2006), Kempe (1948), Kloss (1931), Knapen (1997), Linkie & Sadikin (2003), Lyon (1908), Medway (1977), Meijaard (2000), Ong et al. (1999), Pfeffer (1959), Pfeffer & Caldecott (1986), Piper & Rabett (2009).

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. b. barbatusMuller, 1838 — BorneoandassociatedIs, possiblyextendingtoTawiTawi. S. b. oi Miller, 1902 — Peninsular Malaysia , Sumatra, and Bangka.