Bawean warty pigs
Male and female Bawean warty pigs Bawean Endemics Conservation Initiative, BEKI

The population of one of the rarest pig species has been assessed for the first time, showing there are just 250 adult Bawean warty pigs left on the Indonesian island of Bawean. The species - Sus blouchi – is not yet listed on the IUCN/SSC Red List, but researchers carrying out the assessment say the findings mean it should be listed as endangered.

The Bawean warty pig is found solely on Bawean – a 192 km2 island in the Java Sea. They are very similar to the Javan warty pig, but morphological differences led researchers to propose its upgrade from a subspecies to a species in its own right.

The males are characterised by three pairs of enormous warts on each side of its face and large tufts of golden yellowish hair fanning out from the sides of the head. Females are more difficult to distinguish from its Javan relatives, but they all have a clear band of golden hair running along its abdomen.

Previously, the only information about the Bawean warty pig's behaviour and population was based on anecdotal evidence. Published in the journal PLOS One, researchers have now carried out a detailed estimation of the numbers by using camera traps in 100 locations over three months (over 16,500 hours in total). Scientists from the VHL University of Applied Sciences in the Netherlands, were then able to assess its numbers, behaviour and habitat.

250 adults remaining

Findings showed it had a low population density compared to other species of pig found in Southeast Asia – fewer than 250 adults in total. The pigs were found to be mostly nocturnal and tended to forage in community-owned forests and forest borders. But this habitat preference means they are vulnerable to conflict from locals. Taken together, the team say the Bawean warty pig should be considered endangered on the IUCN Red List.

"Our findings provide a basis for conducting a Red List status assessment for S. blouchi, with the new data allowing the determination of the number of sub-populations, the number of mature individuals, population size and estimated population trend, extent of occurrence and area of occupancy," researchers wrote.

"On behalf of the IUCN/SSC Wild Pig Specialist Group we conducted this assessment and concluded that the species should be listed as Endangered, primarily because of a population size estimated to number fewer than 250 mature individuals. This information may further assist in effective future conservation planning for S. blouchi."