Sus verrucosus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Cetartiodactyla Suidae

Scientific Name: Sus verrucosus Boie, 1832
Infra-specific Taxa Assessed:
Common Name(s):
English Javan Warty Pig, Javan Pig
Taxonomic Notes: Sus verrucosus originally had three subspecies, the nominal subspecies on Java, S. v. olivieri on the island of Madura, which is now thought the be extinct (Blouch 1998), and S. v. blouchi of Bawean Island. S. v. blouchi was upgraded to full species by Groves and Grubb (2011), but pending additional genetic study it is for now maintained as a subspecies.

Assessment Information [top]

Red List Category & Criteria: Endangered A2cd ver 3.1
Year Published: 2016
Date Assessed: 2016-01-12
Assessor(s): Semiadi, G., Rademaker, M. & Meijaard, E.
Reviewer(s): Chiozza, F.
Listed as Endangered because of a serious population decline, estimated to be more than 50% over the last three generations (approximately 18 years), primarily caused by a decline in suitable habitat, especially of stands of teak Tectona grandis forest or similar forest plantations, and by high hunting pressure.
Previously published Red List assessments:

Geographic Range [top]

Range Description:The Javan Warty Pig is endemic to Indonesia. Historically the species was present on Java, Madura Island and Bawean Islands; now the species is very fragmented into small pockets of suitable habitat (Grubb 2005). It is extinct on Madura (Semiadi and Meijaard 2006). Two subspecies are recognized. The nominate form, Sus v. verrucosus, occurs on Java (and formerly Madura) where it is sympatric with Sus scrofa vittatus. The second subspecies, S. v. blouchi is confined to Bawean Island in the Java Sea where it is also sympatric with Sus scrofa vittatus. This species was widespread on Java as recently as 1982 (Semiadi and Meijaard 2006), but is now absent from most of the island, and is surviving only in highly fragmented populations.
Countries occurrence:
Indonesia (Jawa)
Additional data:
Estimated area of occupancy (AOO) - km2:100000Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):UnknownEstimated extent of occurrence (EOO) - km2:2500-5000
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):Unknown
Number of Locations:5-10Continuing decline in number of locations:Yes
Extreme fluctuations in the number of locations:Unknown
Upper elevation limit (metres):800
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The species occurs in at least 10 isolated areas on mainland Java, although some additional, probably very small populations, might survive elsewhere (Semiadi and Meijaard 2006). For example, recently another pocket area was found in Banjar (West Java), though intensive survey work is needed to establish the size of the area and the population (Semiadi 2007 unpubl. data). There are no estimates of overall population size, but the species has shown a rapid population decline in recent decades. Compared to a survey conducted in 1982, 17 of the 32 (53%) populations are extinct or have dropped to low encounter rate levels (Semiadi and Meijaard 2006).

Semiadi and Meijaard (2004), as a result of widespread interviews, reported the species from the following areas:
  1. S. verrucosus occurs in the area between Malingping and Rangkasbitung, but is rarely encountered. There were no reports of recent kills of verrucosus, but some were shot several years ago. Semiadi and Meijaard (2006) considered that that a small population probably remains. However, because S. scrofa is a major agricultural pest, hunting intensity is high
  2. Pigs are common in the area between Sukabumi and the coastal nature reserve of Cikepuh, and are considered a major agricultural pest. S. verrucosus, however, is rarely encountered, with two hunters reporting that they had not shot one since 1998. One hunter suggested that over-hunting was the most likely cause of the species’ decline.
  3. Interviewees in the area near Purwakarta reported the presence of S. verrucosus between the 1960s and 1990s, with steady declines of the weight of killed animals and numbers of pigs encountered. They now consider verrucosus to be very rare, the latest report being a specimen that was shot in 2001.
  4. Near and south of Garut several small populations remain, with reported sightings of S. verrucosus in 2002 and 2001.
  5. Around Majalengka and towards Sumedang interviewees reported recent sightings or killings of S. verrucosus, but all emphasize that the species is now much rarer than in the past. Pigs are much sought after here for illegally organized fights with dogs.
  6. A population of S. verrucosus still exists east of Tasikmalaya towards Ciamis. There were several reports of recent sightings or killings. Still, people consider S. verrucosus to be rare in comparison to S. scrofa.
  7. Several interviewees reported recent sightings of verrucosus from the area around Cilacap, Cipatujuh, and Nusakambangan Nature Reserve, including some from the Nusakambangan Nature Reserve offshore Cilacap, but the species seems to be rare and fragmented into many small populations.
  8. S. verrucosus is still relatively common around Subah, generally seen in small groups of 1–2 animals, but in up to 4–6 animals/group during mating season. Females with young are seen between August and December. S. verrucosus has not declined as much as S. scrofa, but one interviewee expected rapid population declines of the former because teak forests, its prime habitat, are disappearing.
  9. S. verrucosus appears to be relatively common around Blora and Bojonegoro, and every interviewee was familiar with the species and confirmed its local presence. Still, according to one interviewee, the species used to occur in groups of 10–20 animals, but now only 1–3 animals/group are encountered. Five to seven years ago, every hunt resulted in the capture of 1–2 S. verrucosus, or 2–3 according to another informant, but now the species is rarely caught; the most recent one in April/May 2003. One interviewee reported that pigs have especially declined since the fall of President Suharto in 1998, because then local people started to log the state-owned teak forests.
  10. Bawean island is the only area where the subspecies S. v. blouchi occurs. Several interviewees reported the presence of S. verrucosus on the island, but all sightings predated 2002, and the reports gave the impression that the species was now rare. A recent (c. 2004) survey of Bawean deer Axis kuhli on Bawean Island also yielded disturbing reports of the likely dramatic diminution of this species and all wild pig populations (including S. v. blouchi) on Bawean Island, reputedly as a consequence of severe hunting pressure following the transmigration settlement of Christian communities from Sumatra (these animals having been previously left mostly undisturbed by the formerly predominant Moslem communities; R. Ratajszsak, unpubl; pers. comm. to W. Oliver).
Current Population Trend:Decreasing
Additional data:
Population severely fragmented:Yes

Habitat and Ecology [top]

Habitat and Ecology:The species occurs both in cultivated landscapes and in teak forest plantations (Semiadi and Meijaard 2006), with the highest density thought to occur between Semarang and Surabaya on both sides of the border between the provinces of Central and East Java. Recent data (Semiadi 2008, unpubl data) indicate that near Banjar (West Java) there is a possibility of significant numbers of animals in a fragmented teak forest and mixed local and agricultural forest.

The vegetation in which they occur is dominated by mixed age teak (Tectona grandis) plantations interspersed with lalang grasslands (Imperata cylindrical), brush and patches of secondary forest. This apparently provides an optimum habitat for this species. Javan Warty Pigs are everywhere restricted to elevations below about 800 m. The reasons for this are not known, but it might be due to their being unable to tolerate low temperatures (Blouch 1993). They evidently prefer secondary or disturbed forests, though they are also often found near the coasts in remnant patches of mangrove and swamp forest such as in Pangandaran (West Java) and Cilacap (Central Java). They are rare in the few remaining lowland primary forests, and in areas with high human populations where otherwise suitable habitat is fragmented and surrounded by agricultural land. However, they do feed on crops, making nocturnal raids on fields of corn and cassava and, in common with Sus scrofa, the species is widely persecuted for such depredations (Blouch 1988).
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):6

Use and Trade [top]

Use and Trade: The species is widely hunted as an agricultural pest, also because hunters do no differentiate it from the sympatric Sus scrofa (Semiadi and Meijaard 2006).

Threats [top]

Major Threat(s): Semiadi and Meijaard (2006) hypothesized that the population decline observed in this species is primarily caused by a decline in suitable habitat, especially of stands of teak Tectona grandis forest or similar forest plantations, and by high hunting pressure. With the imposed regulation by the government for teak plantation forests to adopt a mixed agriculture system (agroforestry system) by cultivating agricultural products in between the young teak plantations, teak plantation forests become suitable Sus verrucosus habitat. However, a 35-50 year cycle of teak forest harvest remains a threat for the availability of this habitat. In any case, there is extensive illegal logging of teak plantations, no doubt to the detriment of S. verrucosus. These animals are killed both by sport hunters and by farmers protecting their crops (Blouch 1995). Many animals are killed by poisoning (Semiadi and Meijaard, 2006). As yet unpublished reports of the recent dramatic reduction in numbers, possibly resulting in the extirpation, of S. v. blouchi, on Bawean Island have been attributed to correspondingly increased hunting pressure following the recent settlement of Christian immigrants from Sumatra; these animals having been previously left largely unharmed by the predominantly Moslem inhabitants. Competition from and hybridization with the Eurasian wild pig, Sus scrofa has been speculated as a further threat to S. verrucosus, especially in areas where human induced habitat changes have favoured S. scrofa, though there is little direct evidence for this and the two species evidently occur sympatrically in some areas, including Bawean Island.

Conservation Actions [top]

Conservation Actions: Javan warty pigs are poorly represented in existing protected areas. Creation of three new nature reserves and expansion of two existing reserves of importance to the taxon were recommended (Blouch 1993). In addition, surveys of the extent of market hunting should be undertaken with the objective of formulating means to regulate or eliminate the practice, and ecological research and investigation on crop damage should be conducted. Captive animals need to be administered under a properly structured plan for the long term genetic and demographic benefit of the species. 
A captive breeding project of S. v. verrucosus is underway and it is breeding the species successfully. A second breeding program is under development. Breeding is so successful that identification of a suitable release site has become urgent. Very few people on mainland Java, however, would gladly welcome releases of the species in their neighbourhood. Suitable release sites therefore need to be identified in well managed protected areas or offshore islands where no people live.

Citation: Semiadi, G., Rademaker, M. & Meijaard, E. 2016. Sus verrucosus. The IUCN Red List of Threatened Species 2016: e.T21174A44139369. . Downloaded on 24 September 2018.
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