Hyper-abundance of native wild pigs (Sus scrofa) in a lowland dipterocarp rain forest of peninsular Malaysia

This study reports extraordinarily high density estimates for the wild pig (Sus scrofa) from ail aseasonal tropical Forest site within the species' native range. At Pasoh Forest Reserve, a 2500 ha area of lowland dipterocarp rain forest in Peninsular Malaysia, line transects were used to estimate pig density front May to October in 1996 and 1998. In 1990, 44 sightings of S. scrofa consisting of 166 individuals were recorded along 81 km of transects. In 1998, 39 sightings documented 129 individuals along 79.9 km of transects. Estimated population density was 47.0 pigs/km(2) in 1996 and 27.0 pigs/km(2) in 1998. Sus scroll biomass in this forest was estimated at 1837 kg/km(2) and 1346 kg/km(2) in 1996 and 1998, respectively. Differences between Years were attributed to changes in the density of young pigs, coincident with a mast-seeding year of dipterocarp trees in 1996. Pig densities at Pasoh Forest Reserve were much higher than at other forest locations within the species' native range in Europe and Asia. Because Pasoh Forest Reserve is a forest fragment, two factors likely account for the extremely high pig densities: (1) local extinction of natural predators (mainly tigers and leopards) and (2) an abundant Year-round food Supply of African oil palm fruits from extensive plantations bordering the reserve.