The bearded pig in East Kalimantan and Sarawak
Pfeffer and Caldecott (1986) present a translated and revised account of Pfeffer’s 1959 French-language field study of the bearded pig (Sus barbatus) in East Kalimantan, supplemented with Caldecott’s more recent observations in Sarawak, to document the species’ ecology, its enigmatic mass migrations, and its critical role in the subsistence economy of Borneo’s forest peoples.
Summary
The article addresses a significant gap in the English-language literature on Bornean mammal ecology. Pfeffer’s original 1959 study, published in French in Mammalia, had been essentially unavailable to the broader community of zoologists, anthropologists, and conservation workers active in the region. The present work translates and revises that account, updating taxonomic nomenclature to reflect Groves’ (1981) reclassification of the genus Sus, and appends a commentary by Caldecott drawing on his own fieldwork in Sarawak during the early 1980s.
The core of the text is Pfeffer’s year-long field study (July 1956–July 1957) in the river basins of East Kalimantan, where he documented the bearded pig’s morphology, diet, diurnal activity patterns, nest construction, reproductive behaviour, and—most notably—its massive periodic migrations. Pfeffer distinguished between a resident sedentary population and a transitory migratory population, and identified two principal annual migration pulses following fixed routes from the upper Sembakung, Sesayap, and Malinau basins southward toward the Mahakam. The migrations resist explanation by food availability alone, since migrating animals are often fat and the movements occur regardless of local fruiting conditions. Pfeffer could not determine whether the movements represented seasonal round-trips or definitive emigrations, a question he left open.
Caldecott’s commentary extends the analysis to Sarawak, where he identified a key feeding ground of submontane Lithocarpus (oak) forests along the East Kalimantan frontier as a likely driver of the population dynamics Pfeffer observed. He proposes a “phenological mosaic” model in which pigs aggregate around fruiting areas, breed, and then disperse in pulses as fruiting dies away from one locality to the next, with the oak forests acting as a nutritional subsidy that fuels both reproduction and long-distance movement.
Key Findings
- Two major annual migrations occur in August–September and December–January, with animals moving southward from the upper Sembakung, Sesayap, and Malinau basins along four principal routes toward the Mahakam (pp. 91–92).
- During peak migration, herds of 20–30 or more cross rivers simultaneously; in 1954, thousands of carcasses accumulated at Tanjung Selor, prompting the Muslim Malay population to declare “war” on the Dayak hunters responsible (p. 94).
- Adult males routinely reach 100–150 kg, with some individuals attaining 200 kg during fruit seasons; tusks measure 25–30.5 cm in males and 19–21 cm in females, with exceptional curled tusks reaching 44–46 cm (pp. 86–87).
- Subcutaneous fat thickness increases from 3 cm at the neck two weeks into a fruit season to 5–6 cm (and up to 9 cm) four to six weeks later (p. 88).
- In Sarawak, bearded pigs contributed 32% of all meat and fish consumed at 63 interior boarding schools in 1984–1985, and at least 90% of the estimated 54 kg of wild meat consumed per person per year in undisturbed areas (pp. 99–100).
- Pfeffer recorded a previously unreported association between the bearded pig and the crested wood partridge (Rollulus rouloul), in which the birds feed on fruit fragments dropped by the pig and appear to remove external parasites (pp. 96–97).
Conclusion
The authors argue that the bearded pig’s persistence despite intense and continuous hunting is a function of Borneo’s sparse human population, the absence of large carnivores, and the vast extent of intact rainforest. They warn, however, that the ongoing “holocaust of habitat change”—logging, forest fires, transmigration—threatens the species by fragmenting the forest cover and systematically destroying the key oak-forest feeding grounds that subsidize both reproduction and the long-distance movements on which the species’ population dynamics depend.
Context
- The article is primarily a translation and revision of Pfeffer’s 1959 French-language monograph (Mammalia 23: 277–303), made accessible to the English-reading scientific community, with a supplementary commentary based on Caldecott’s fieldwork in Sarawak (1982–1986).
- Its historiographical contribution lies in bridging the gap between Pfeffer’s detailed but linguistically isolated observations and the emerging English-language conservation literature of the 1980s, while providing the first comparative framework between East Kalimantan and Sarawak bearded pig populations.