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Pigs, Peccaries and
Hippos Status Survey and Action Plan (1993) Chapter 5.4 The Javan Warty Pig (Sus verrucosus) Raleigh A. Blouch Status and Action Plan Summary Both subspecies are status category 4 (vulnerable). The Javan warty pig is endemic to the islands of
Java, Madura, and Bawean in Indonesia. Two subspecies are recognized. These
are S. v. verrucosus from Java and
Madura (though it is reported to be extinct on Madura, following the virtual
deforestation of that island), and S.
v. blouchi from Bawean Island, off N. E. Java. The current status of the
latter form, which was described as recently as 1981 (Groves, 1981), is not
known, but it is thought to be relatively secure despite its extremely
limited range. The nominate form is not uncommon on Java, but the remaining
populations are highly fragmented and the species is poorly represented
within existing nature reserves. It is widely persecuted as a pest, but some
segments of society value it as a game animal and for its meat. Poisoning and
uncontrolled hunting are the greatest threats. Habitat loss is not currently
a major problem over most of its remaining range, since the species is found
on marginal lands with little potential for agriculture, or on land already
devoted to teak plantations. The principal recommendations for the conservation
of the nominate Javan population include: 1) the creation of three new nature
reserves totaling 32,000 ha, and expansion of two existing reserves to
include an additional 20,000 ha of warty pig habitat; 2) gaining control of
the harvest by improved regulation of sport and market hunting, and
elimination of the use of poisons; 3) expansion of the current captive
breeding program for S. v. verrucosus;
and 4) investigations into the extent of hybridization with wild S. scrofa to determine whether this
poses a potential threat to the genetic integrity of S. verrucosus. Field surveys are required to determine whether
any remnant populations of this subspecies survive on Madura and to assess
the present status and future management needs of the Bawean form. Introduction The Javan warty pig is endemic to the Indonesian
islands of Java, Madura, and Bawean. Little was known about the natural
history of this species until, prompted by fears that it may have become
extinct in the wild (J. MacKinnon, 1981 and pers. comm; National Research
Council, 1983), a thorough survey of its range was conducted during 1982,
under the aegis of the W.W.F.- Indonesia Conservation for Development
Programme (Blouch et al., 1983,
Blouch 1988). Two subspecies are recognized. The nominate form, S. v. verrucosus, occurs on Java and
on the neighboring large island of Madura, though MacKinnon (1981) reported
the species was extinct in the latter area. It is sympatric with S. scrofa vittatus on Java. The second
subspecies, S. v. blouchi,
described by Groves in 1981, is confined to Bawean Island in the Java Sea,
where its present status is uncertain despite the establishment of a 4,500 ha
nature reserve in 1979. For adult males of both races the most distinctive
feature is the presence of three pairs of facial warts - the preorbital,
infraorbital and the large mandibular warts. There is considerable individual
variation in the size of these, and the females do not exhibit these pronounced
features (Groves, 1981; Groves and Grubb, this vol.). The nominate race is
larger than the Bawean form, though little comparative data is available, and
shows marked sexual dimorphism in body size, viz: mean live weights for adult
males being about 108.2 kg (n=5, s.d.= 17.48) and for adult females only
about 43.9 kg (n=4, s.d.=5.75) (Hoogerwerf 1970). Javan warty pigs are of
some interest to animal breeders because of the potential value as
domesticates (National Research Council, 1983). Possible advantages include
the small size of the sows, which could make the species appropriate for
households or smallholder farms, and the genetic distance of the species from
the (ex-S. scrofa) domestic pigs, which may make it a useful generator
of heterosis in crossbreeds. Link to Fig. 12: Approximate
former and present distribution of the Javan and Bawean warty pigs, Sus
verrucosus ssp., and the closely allied Vietnamese warty pig, Sus
bucculentus. Former and Present Distribution There is little reliable information on the former
distribution of the species within its restricted range. This is partly
because most early references to the natural history of the wild pigs of Java
did not differentiate between verrucosus
and scrofa, presumably because of
the difficulty of distinguishing these species under field conditions.
However, there is no doubt that its range on Java has also been greatly
reduced and fragmented during the last century. For example, it is known that
it formerly occurred in Udjung Kulon National Park (Hoogerwerf, 1970) where
it is no longer present, possibly because of human-induced vegetation changes
(Blouch, 1988). The species might also be expected to occur in or around Blambangan
Nature Reserve in extreme south-east Java, and in Baluran National Park in
the extreme north-east, both of which include substantial amounts of
apparently suitable habitat (see later text), though no evidence of its
occurrence in either of these areas was obtained during the 1982 survey.
Since World War II the increasing human population and resultant habitat
fragmentation has also resulted in the elimination of Javan warties in the
lowland areas 50 km south-east of Jakarta. Javan warties are also reported to be extinct on the
neighboring large island of Madura following its almost complete
deforestation (J. MacKinnon, pers. comm.), though this island was not visited
during the 1982 survey and it is possible that a few still exist there. The subspecies blouchi
is confined to the small (20,000 ha) island of Bawean, 150 km north of
Surabaya in the Java Sea. Formerly, it would have occupied the coastal
lowlands, but these areas have now all been converted to the cultivation of
rice and other crops. Consequently, the warties are now predominantly
concentrated in the teak plantations in the hilly central parts of the
island, where most of this habitat is included within the Bawean Island
Nature Reserve (Table 7). In West Java much of the terrain is mountainous and
therefore unsuitable for verrucosus, though there is a narrow plain
about 150 km long on the south coast, which provides habitat for good numbers
of the species. The vegetation in this area includes lalang (Imperata cylindrica) grasslands and
scrubby secondary forest, mixed with dryland agriculture and coconut
plantations. The 2,000 ha Leuweung Sancang Nature Reserve in this region is
one of the few existing protected areas to contain Javan warty pigs. Two
other areas of extensive lalang grasslands with substantial numbers of verrucosus are located north of
Bandung and east of Ujung Kulon National Park. South and east of Surabaya the landscape of east
Java is dominated by a series of large volcanoes and the verrucosus populations are mostly small and confined to the lower
slopes. A few are found within the Meru Betiri National Park, but the habitat
is predominantly heavily forested and unsuitable for the species. Habitat, Ecology and Behaviour Most births of Javan warty pigs occur during the
rainy season months of January, February, and March. Litter size ranges from
three to nine (Sody, 1941). The largest groups of warty pigs reported in Java
consisted of only four to six individuals, suggesting that several sows and
their young do not band together, as is the case with the (sympatric) S. scrofa. Adult male warty pigs are
usually solitary except during the mating season (Blouch et al., 1983). The largest remaining concentration of S. v. verrucosus is in the extensive
teak plantations between Semarang and Surabaya on both sides of the border
between the provinces of Central and East Java. The vegetation is dominated
by mixed age teak (Tectona grandis)
plantations interspersed with lalang grasslands, brush and patches of
secondary forest. This apparently provides an optimum habitat for this
species, which is common or even abundant in some areas, though declining
elsewhere. In contrast, S. scrofa is rare or absent throughout much of
this part of Java. 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. They
evidently prefer secondary or disturbed forests, though they are also often
found near the coasts in remnant patches of mangrove and swamp forest. 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 S.
scrofa, the species is widely persecuted for such depredations (Blouch,
1988). On Bawean Island, S. v. blouchi is found in
habitat similar to that of north-western East Java, i.e. teak plantations
with scattered patches of secondary growth, lalang openings, and mature
forest on the tops of hills. They are also considered a pest by farmers, who
sometimes kill them with dogs and spears, though they are never eaten owing
to the strict Islamic faith of the islanders. Threats to Survival With the elimination of the tiger (Panthera tigris sondaica) from Java,
and reduction in the number of Asiatic wild dogs (Cuon alpinus), the leopard (P.
pardus) is probably the only large carnivore which regularly preys on
wild pigs, though its impact on the remaining populations of these animals is
unknown. In any event, human predation and persecution undoubtedly
constitutes the greatest threat to this species. Although it is illegal,
poisoning is particularly widespread, and stories abound of poisoners
killing, for example, 10 to 40 pigs per night or well over one hundred in one
week. The largest remaining populations located between Semarang and Surabaya
have been drastically reduced by poisoning in some areas. It is also a
significant problem immediately west of Semarang, around Nusa Kambangan
Nature Reserve, on the border between Central and East Java in the south,
throughout the southern coastal plain in West Java, and in the Pembarisan
Hills. Much of this poisoning is done for the purpose of selling the meat for
human consumption rather than to protect crops. Uncontrolled hunting poses an additional threat. A
hunting license entitles the holder to take five wild pigs of either species
per year and imposes other restrictions such as a three-month closed season
and a ban on night hunting with spotlights. However, due to lax enforcement,
most of the regulations are ignored even by those who purchase the 600
licenses sold annually in Java. Although there is no way of knowing the
number of firearm hunters who do not purchase licenses, it almost certainly
exceeds the numbers who do. Illegal hunting is practiced by many police and
military personnel as well as by some market hunters. Rural people still hunt
wild pigs with dogs and spears, but the use of these more traditional
methods, as well as the numbers of pigs, seems to have dwindled in recent
years commensurate with the more common use of poison. For thousands of years the Javan warty pig has coexisted
with the more numerous native S. scrofa,
suggesting that hybridization does not threaten the genetic integrity of the
species under normal conditions. Nonetheless, a probable hybrid was
identified among 31 specimens examined, indicating that a low level of
crossbreeding may now be occurring in the wild (Blouch, 1988; Blouch &
Groves, 1990). If so, it is possible that habitat reduction and fragmentation
coupled with a reduction in numbers of one species may have resulted in the
localized breakdown of the natural isolating mechanisms between the two
species. However, there is no information on the reproductive success of the
hybrids and, hence, the potential deleterious effects on the verrucosus
gene pool. In comparison, habitat loss is thought to pose a
relatively minor threat at the present time, since Javan warties tend to
occupy either marginal lands with little potential for agriculture or teak
plantations, which are unlikely to be converted to other forms of land, use. Conservation Measures Taken Little regard has been paid to the conservation of
this species to date, except that it is classed as a game animal and a
license is required to hunt it. However, due to a lack of enforcement
personnel, the hunting laws are largely ignored and only occasional efforts
are made to stop poisoning. An island-wide survey of Java was undertaken in 1982
to determine the distribution and status of S. v. verrucosus. This resulted in a number of recommendations
for the enhanced future management of this species, though many of these have
yet to be implemented. Commensurate with the findings of this survey, and the
fact that the only protected area to harbor a sizeable population of Javan
warties is the small Leuweung Sancang Nature Reserve (Table 7), the species
has been categorized as "Vulnerable" in the IUCN Red List of
Threatened Animals since 1986 (IUCN, 1986). Most of the remaining habitat of the Bawean
subspecies, S. v. blouchi, is
included within the Bawean Island Wildlife Reserve (4,500 ha). This Reserve
was created in 1979 with the main objective of conserving the Bawean deer (Axis
kuhlii), which is endemic to the island (Blouch and Sumaryoto, 1979).
However, very little if any additional information on these animals has been
obtained over the last ten years, and their present status is not known.
Nonetheless, given their restricted habitat and the fact the Island supports
a relatively high (>70,000) human population, it would be unrealistic to
suppose that they are securely established. |
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Table 7. Protected areas known to support Sus verrucosus. ______________________________________________________________________________________
Protected Area Size (sq km) Comments ______________________________________________________________________________________
S. v. verrucosus Leuweung Sancang Nature Reserve 20 Both
S. verrucosus and S. scrofa relatively common but, given
the relative importance of this Reserve, it should be enlarged
to benefit the warties Nusakambangan Nature Reserve 9.3 Available habitat probably more suitable for S. scrofa which
also occurs here; the Reserve should be extended northwards
to incorporate more verrucosus habitat. Meru Betiri National Park 50 A few verrucosus occur in disturbed areas; predominant vegetation
is dense forest more suited to S.
scrofa. S. v. blouchi Bawean Island Nature Reserve 45 Size of remnant pig population unknown, and mostly confined
to teak plantations. |
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Captive Breeding The largest Javan warty pig breeding colony is
maintained at the Surabaya Zoo in East Java where a total of 11 (9GG, 2EE) individuals were maintained in
1987. By September 1990, there were at least 17 (? sexes) individuals
(including two litters born that year) in Surabaya, and a further 4 (2GG2EE) at the Gembiraloka Zoo in
Yogjakarta, and one G at Ragunan Zoo in Jakarta, on
loan from Surabaya Zoo (A. Macdonald, pers. comm.). All of these are
descendants of about seven animals obtained from the wild in the late 1970's
and early 1980's. In addition, in 1982 the Semarang Zoo in Central Java was
holding one E unrelated to the Surabaya Zoo
stock. Unfortunately, some of the Surabaya Zoo stock has
been offered for sale on the open market since late 1989, thereby
compromising the possibility of promoting the development of a properly
structured, co-operative breeding program through the placement of surplus,
captive-bred animals to other reputable breeding centers under the aegis of
breeding loan agreements. Conservation Measures Proposed: An Action Plan It is apparent that the Javan warty pig is not in
any immediate danger of extinction and, indeed, it remains fairly common in
some areas where it may cause considerable damage to crops. It is not,
therefore, either necessary or practicable to attempt to protect all
surviving populations outside the (few) protected areas in which it occurs.
However, due to uncontrolled poisoning and hunting pressure, some local
populations are in decline and likely to be eliminated, and the overall
conservation status of this species must give cause for concern. The ultimate conservation objective for this species
should be to expand the area of Javan warty pig habitat within nature
reserves so that several viable populations can be given complete protection,
whilst managing other populations as a harvestable resource providing
opportunities for recreational hunters whose activities will maintain
populations at levels where their depredations on crops are tolerable. This
approach will also generate income for local people who provide food,
lodging, and guide services to the hunters. These objectives and the priority
projects designed to achieve them may be summarized as follows: Objectives: 1. To extend
the existing network of protected areas to provide complete protection to
several, selected Javan mainland populations by including their habitat
within nature reserves. 2. To conserve
as many of the remaining viable populations of Javan warties outside of
protected areas as possible by managing them for meat and sport hunting. 3. To develop
appropriate management strategies for the enhanced future protection of any
possibly surviving populations on Madura and the sole remaining population of
the endemic subspecies, S. v. blouchi,
on Bawean Island. 4. Maintain
breeding colonies in zoos to serve as an insurance and as a source of animals
for possible future reintroduction attempts (e.g. to Madura) and as material
for studies of the biology and potential value of the species as a genetic
resource. Priority Projects: 1. Create three new nature reserves suitable for the
conservation of Javan warty pigs. These are: (1) a 13,000 ha area of
rain forest in the Pembarisan Hills lying mostly above 650 m altitude, where
good numbers of verrucosus coexist
with scrofa at the lower elevations
on the disturbed fringes of the forest; (2) a 16,000 ha area of lowland
forest on limestone soil at Teluk Lenggasana on the south coast of East Java;
and (3) the consolidation of the proposed Mt. Ringgit and Mt. Beser reserves
in East Java, which are presently situated 10 km apart and total only 3,000
ha of disturbed monsoon forest below 500 m altitude, but which would afford
potential protection to one of the largest verrucosus populations remaining east of Surabaya if made into
one larger reserve. Besides supporting viable verrucosus populations, all three of these areas have other
important conservation merits and all have been recommended as nature
reserves in the National Conservation Plan for Indonesia (FAO, 1982). 2. Extend two of the existing nature reserves to
include more Javan warty pig habitat. These are: 1) The 2,000 ha
Leuweung Sancang Nature Reserve, which should be increased by as much as
16,000 ha, thereby also benefiting the resident population of banteng (Bos javanicus); and 2) the 930 ha
Nusakambangan Nature Reserve, which should be expanded northward to include
the 5,000 ha of mangroves and lowland forests known as Segara Anakan. 3. Conduct a field status survey on Madura. This is necessary to determine
whether any remaining populations of S.
v. verrucosus occur there, with a view to the development of
recommendations for their protection and/or the identification of sites for
possible future reintroduction. 4. Conduct a field status survey on Bawean. The present status of S. v. blouchi should be assessed, and
management recommendations formulated to benefit this subspecies and other
endemic taxa. 5. Concentrate law enforcement and public education
efforts in most critical areas. Priority should be given to Bawean
and those parts of Java where S.
verrucosus is the predominant pig species, with a view to the better
control of illegal hunting pressure and the elimination of poisoning. 6. Clarify the ecological and genetic relationships between
S. verrucosus and S. scrofa. Research should be initiated to
elucidate these relationships with regard to interspecific competition for
resources and the incidence of hybridization. 7. Conduct a
survey of market hunting of wild pigs to determine its extent and formulate
means of regulating or eliminating this practice 8. Assist development of a captive-breeding program
in Indonesia and elsewhere. All captive individuals should be
individually marked and registered in a studbook, and the breeding program
developed by means of a properly structured plan for the long term genetic
and demographic management of this species, including the early extension of
the present stocks in Javan collections to other breeding centers elsewhere.
Sales of individuals of this species should be suspended or prohibited. Acknowledgements Much of our current knowledge of the Javan warty pig
originates from the 1982 survey funded by the World Wildlife Fund. Personnel
of the Indonesian Directorate General of Forest Protection and Nature
Conservation provided invaluable assistance on this survey, especially Ir.
Wartono Kadri, Dr. Sumaryoto A., Ir. Heri D. S. and Ir. Banjar Y. L. Ir.
Bambang S. and other officials of the Surabaya Zoo were helpful on many
occasions. William Oliver, Dr Alastair Macdonald, Dr. Colin Groves and
Michael Riffel all provided invaluable comments on earlier drafts of this
text, and Paul Vercammen and Peter Cuypers prepared the range maps. References Blouch, R. A.
and Sumaryoto, A. 1979. Proposed Bawean Island Wildlife Reserve Management
Plan. (Unpubl.) rep. to WWF-Indonesia Programme and Directorate of Nature
Conservation, Rep. Indonesia: 82 pp. Blouch, R. A.
1988. Ecology and conservation of the Javan warty pig Sus verrucosus Muller, 1884. Biol. Conserv. 43: 295-307. Blouch, R. A.,
Banjar Y. L., Heri D. S., and Sumaryoto A. 1983. The Javan Warty Pig:
Distribution, Status and Prospects for the Future. (Unpubl.) rep. to World
Wildlife Fund, Bogor: 32pp. Blouch, R. A.
and Groves, C. P. 1990. Naturally occurring suid hybrid in Java. Zeitschrift
fur Saugetierkunde, 55: 270-275. FAO 1982.
National Conservation Plan for Indonesia, 3: Java and Bali. (Unpubl.) Field
Report 36, UNDP/FAO (FO/INS/78/061) Nature Conservation and Wildlife
Management Project, Indonesia. Groves, C.
1981. Ancestors for the Pigs: Taxonomy and Phylogeny of the Genus Sus. Tech. Bull. 3. Dept. Prehist.,
Australian National University Press, Canberra: 96pp. Hoogerwerf, A.
1970. Udjung Kulon, the Land of the Last Javan Rhinoceros. E. J. Brill,
Leiden: pp 331-349. IUCN 1986. IUCN
Red List of Threatened Animals. IUCN, Gland and Cambridge. MacKinnon, J.
1981. Distribution and status of wild pigs in Indonesia. (Unpubl.) rep. to
IUCN/SSC Pigs and Peccaries Specialist Group: 9pp. National
Research Council 1983. Little-known Asian Animals with a Promising Economic
Future. National Academy Press, Washington D. C.: pp 80-84 & 122-123. Sody, H. J. V.
1941. Tweede bijdrage ouer de voort-platinestijden del Indische zooedieren. Der
Nederlansch-Indische Jager, II: 198-201. |
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Next: Chapter 5.5 – The
Bearded Pig |