Oryx Vol 40 No 1 January 2006 Declining populations of the Javan warty pig Sus verrucosus Gono Semiadi and Erik Meijaard Abstract We conducted an interview-based survey for hunting pressure. Competition from and hybridization the Javan warty pig Sus verrucosus, endemic to the islands with the Eurasian wild boar Sus scrofa may be further of Java and Bawean in Indonesia. The species occurs threats to S. verrucosus. Rapid action is needed to prevent in 10 isolated areas, although some additional, probably extinction in the wild. We recommend effective pro- very small populations, may remain. Compared to a tection of selected S. verrucosus populations, lobbying survey conducted in 1982, 17 of the 32 (53%) populations of the Government to give protected status to S. verru- are extinct or have dropped to levels so low that local cosus, conducting ecological research and investigating hunters have failed to encounter the species in recent crop damage issues, and establishment of conservation years. This indicates a rapid population decline. We breeding programmes. hypothesize that this loss is primarily caused by a decline in suitable habitat, especially stands of teak Tectona Keywords Ethnobiology, Indonesia, Javan warty pig, grandis forest or similar forest plantations, and by high Suidae, survey, Sus verrucosus, teak. Introduction extinct. Blouch found that S. verrucosus occurred in lowland areas below 800 m, although there are several The Javan warty pig Sus verrucosus is endemic to the museum specimens of S. verrucosus from localities as islands of Java and Bawean in Indonesia. Hardjasamita high as 1,500 m (van Strien, 2001). Its preferred habitat (1987) traced its ancestry to several fossil pig species of consisted of extensive areas of lowland secondary veg- Java and this, together with phylogenetic data (Randi etation, particularly teak Tectona grandis plantations in et al., 1996), suggests isolation on Java for c. 2 million Central Java characterized by a mixture of trees and years. S. verrucosus occurs alongside the Eurasian wild grasslands with clumps of bush and heavily disturbed boar S. scrofa vittatus, which arrived in the Late Middle– Late Pleistocene (van den Bergh et al., 2001). S. scrofa is forest. Blouch also found that S. verrucosus frequented widely distributed throughout Asia and Europe (Oliver coastal forest. S. scrofa on the other hand could be found et al., 1993). Olivier (1925) noted that in West Java both at all altitudes in most habitats. pig species were common and occurred in similar habi- The survey by Blouch located 32 populations across tats, from coastal to montane forests. More recent studies Java, and he concluded that the future of S. verrucosus indicated that the two species avoid each other (Blouch, was reasonably secure. A few years later Blouch & 1988, 1993). Groves (1990) pointed out that hybridization between S. verrucosus was believed extinct in the late 1970s S. verrucosus and S. scrofa posed an unknown, but (J. MacKinnon, pers. comm. to W. Oliver), but a small potentially serious threat, primarily to the survival of S. population was found in 1981 on the forested slopes verrucosus. Two subspecies are recognized: S. verrucosus of Mt Penanggungan near Tretes (Whitten et al., 1996; verrucosus on Java and S. verrucosus blouchi on Bawean Fig. 1). In 1982 Blouch (1988, 1993) conducted a survey Island. Both subspecies are categorized on the IUCN for S. verrucosus; this also included Bawean Island but Red list as Endangered, based on an inferred population excluded Madura Island, where the species was histori- decline, fragmentation of habitat, and the levels of cally known to occur (Sody, 1941) but was presumed exploitation (IUCN, 2004). An Action Plan (Oliver, 1993) accorded the species high conservation priority, and stressed the urgency of implementing relevant conser- Gono Semiadi Puslit Biologi LIPI, Jl. Raya Bogor-Cibinong km 46, vation measures, including the survey described here. Cibinong 16911, Indonesia. Despite the recommendations of the Action Plan, S. Erik Meijaard (Corresponding author) The Nature Conservancy-East verrucosus remains unprotected under Indonesian law. Kalimantan Program, Jl. Kuranji 1, Vorvoo, 75123 Samarinda, Considering the Red List status of S. verrucosus and the East Kalimantan, Indonesia. E-mail [email protected] much-reported decline of Java’s teak forests (Chicago Received 28 June 2004. Revision requested 4 January 2005. Tribune, 8 July 2001; Jakarta Post, 15, 22, & 27 August Accepted 22 April 2005. First published online 19 January 2006. 2001) we considered it likely that the conservation needs 50 © 2006 FFI, Oryx, 40(1), 50–56 doi:10.1017/S003060530600007X Printed in the United Kingdom Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.8, on 02 Oct 2021 at 15:06:12, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S003060530600007X Javan warty pig survey 51 Fig. 1 Java and Bawean Islands, with names of towns and protected areas mentioned in the text; survey routes are indicated by dotted lines (NR, Nature Reserve; NP, National Park). of the species had increased since the 1982 survey and older than 35 years and thus most likely to have wit- that active conservation management may be required nessed longer-term population trends. We also talked to to ensure its survival. the heads of the regional offices of the Indonesian hunt- Our survey is a first step towards assessing the status ing association (PERBAKIN), to policemen who accom- of S. verrucosus. We revisited all populations that were panied or participated actively in hunting excursions, recorded by Blouch. We report our findings by com- and to farmers who had experienced problems with pigs paring the current distribution with that in 1982, and foraging in their fields and gardens. also use distribution records from c. 1840 to 1950 for an We conducted our interviews in a structured manner, historic perspective. Based on the observed population noting the interviewee’s name, age and occupation, fol- trends we provide recommendations for improved lowed by questions relating to crop damage, hunting and conservation management. poisoning, pig population trends, group sizes and breed- ing cycles. We also enquired whether different pig spe- cies occurred in the area, or in which year they had been Methods last seen, and we asked about their physical appearance, Surveys relative abundance and differences in habitat prefer- ences. We showed six photographs (three of each species) We conducted a social survey on Java and the island of to verify the interviewees’ acuity and ability to identify Bawean, c. 125 km north of Java (see Fig. 1 for survey the two species. Sus verrucosus males have pronounced routes). Presence and absence data for S. verrucosus were facial warts, which are absent in S. scrofa, and there are primarily gathered by GS and local field assistants, who also colour and size differences. Females of both species interviewed local informants and conducted field inspec- are similar, making field identification difficult. All inter- tions. There are drawbacks to interview-based survey views were conducted in the appropriate local language techniques as it is difficult to assess the accuracy of infor- (Indonesian, Sundanese or Javanese). If the accuracy of mation collected. Nevertheless, ethnobiological surveys information was in doubt, attempts were made to cor- constitute an important means of rapidly accumulating roborate reports in separate interviews with informants presence/absence data and identifying human-induced in nearby villages. In addition to the field surveys, GS threats. We ensured that our questions were phrased also visited all Javan zoos maintaining S. verrucosus to objectively and took care not to elicit strategic answers gather data about the health, breeding success, sex, age, by obscuring the purpose of our interviews. Because pig and other particulars of captive animals. hunting is common and never punished we are confident that interviewees replied honestly. Our first step was to Distribution range mapping select the most appropriate interviewees, namely those who hunted, trapped or poisoned pigs. We selected Using 1:500,000 vegetation maps (Peta Lingkungan Laut people identified by village headmen, who were mostly Nasional, BAKOSURTANAL, 1992), and for some areas © 2006 FFI, Oryx, 40(1), 50–56 Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.8, on 02 Oct 2021 at 15:06:12, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S003060530600007X 52 G. Semiadi and E. Meijaard 1:50,000 maps (Peta Perjalanan, Indo Prima Sarana, 2000), familiar with S. scrofa. In the remaining 10 interviews we estimated the extent of local distribution ranges of it was unclear whether S. verrucosus still existed (e.g. S. verrucosus by drawing minimum convex polygons last reported sightings 10 or more years previously; for around localities of reported pig sightings and mapping details see Semiadi & Meijaard, 2004). Our survey indi- apparently suitable habitats (forest plantations and cated that, between 1982 and 2003, 17 of the 32 (53%) S. secondary forests) in each location where the species verrucosus populations identified by Blouch (1983) had was reputed to occur. For this we used the vegetation been extirpated or dropped to levels so low that local and topography maps of MacKinnon (1997) and the hunters had failed to encounter the species in recent geographical information system ArcView 3.2 (ESRI, years. In three cases we found that S. verrucosus was Redmond, USA). probably present in locations where Blouch had not reported them. Our data suggest that there are c. 10 Assessment of distribution trends areas on Java and Bawean where S. verrucosus popula- tions survive (Fig. 2, see Semiadi & Meijaard 2004 for To investigate whether there has been a decline in S. details), although very small groups may exist else- verrucosus populations we assessed the historic distri- where.