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Pigs, Peccaries and
Hippos Status Survey and Action Plan (1993) Chapter 5.7 The Sulawesi Warty Pig (Sus celebensis) Alastair A.
Macdonald. Status and Action Plan Summary Status category 2
(locally abundant, but with a restricted distribution). S. celebensis is a medium sized
pig which is common in north, central and eastern Sulawesi, but it is now
scarce in south Sulawesi and may be extinct on nearby Selayar Island, both of
which areas have been largely deforested. It also occurs as a native form on
the adjacent islands of Buton, Muna, Peleng, Lembeh and on some of the Togian
Islands. The species has also been quite widely introduced elsewhere in
Indonesia, e.g. to the islands of Halmahera, Flores, Timor, Lendu and
Simeulue. The wild pigs on some of these islands are strongly modified and
there is now little doubt but that S.
celebensis has been domesticated, and transported to these areas as a
domestic or feral form, probably during the early migrations of settling
peoples. It is still maintained as a domestic form on the islands of Roti and
Savur, near Timor. Whilst continued
habitat destruction, hunting pressure and genetic contamination through
contact with S. scrofa domesticates
represent potentially serious threats to this species, it cannot be regarded
as seriously threatened throughout its range at the present time. For this
reason, recommendations for future action are primarily directed towards
elucidating outstanding questions about: a) the systematic status and future
management needs of populations in certain specified areas within its
original range and in locations to which it can only have been introduced by
human agency; and b) promoting applied research on various aspects of its
biology, its socio-economic significance to village and island societies and
its potential importance as a genetic resource for further domestication. Introduction Sulawesi warty pigs
are medium sized, short-legged animals weighing between 40-70 kg. Recent
forms are larger than the subfossil remains found in caves in southern
Sulawesi (Hooijer, 1950) and the Pleistocene specimen reported by Hooijer
(1969). Adult boars are larger than sows, averaging 60 cm at the shoulder
(National Research Council, 1983). Adult animals are usually dark-haired,
although some individuals are reddish-brown or yellowish in color, sometimes
with lighter colored hairs on the trunk and abdomen (Groves, 1981,
Hardjasasmita, 1987). A clear yellow snout band is usually present, along
with a distinctive tuft or 'crest' of longer hair on the crown of all but the
oldest adults. Adult males have three pairs of facial warts: the preorbital
pair is the largest, the infraorbital somewhat smaller and the mandibular
warts emerging from a whorl of hair marking their position to enlarge and eventually
dominate (in captive specimens at least). Recent studies of
Bosma et al. (1991) indicate that
the Sulawesi warty pig, like the other Asian Sus spp., has a chromosome number of 38. However, there are
significant differences in the banding of its Y chromosome when compared with
either S. scrofa or S. verrucosus. The only anatomical
study to date, was of a female reproductive tract, which was found to be
indistinguishable from that of S.
scrofa (Macdonald et al.,
1984). Link to Fig. 15:
Approximate distribution of native and introduced (including domestic and
feral) populations of the Sulawesi warty pig, Sus celebensis. Former and Present Distribution Available evidence
suggests that the species formerly occurred throughout Sulawesi, as well as
on the neighboring islands of Selayar, Buton, Muna, Peleng, Lembeh and the
Togian Islands. MacKinnon (1981) reported that the species remained extremely
abundant throughout north, central and south-eastern Sulawesi, despite
hunting pressure and agricultural development, but that it was extinct or
greatly reduced in numbers in south-west Sulawesi, and on nearby Selayar,
following the virtual deforestation of these areas. Wild pigs referred
to as feral S. celebensis by Groves
(1981), are known from Halmahera, Flores, Timor, Lendu and Simeulue and Nias
islands, and domesticated animals of S.
celebensis derivation are reported from the islands of Roti and Sawu
(Groves, 1983; Bell, 1987). The present working hypothesis is that the
species was transported by man to the Mollucas and along the Lesser Sunda
chain of islands either as a domesticate or as a barely modified wild form
which was released to be hunted whenever required for eating. In the Mollucas,
and possibly elsewhere in this region, these introduced celebensis are thought to have hybridized with other introduced
pigs of S. scrofa derivation, and
apparent hybrids between these species are now reported to survive on a
number of islands in this region, including Salawatti, Great Kei Island,
Dobu, Seram, Ambon, Bacan, Ternate, Morotai and New Guinea (Groves 1981,
1983; Oliver and Brisbin, this vol.). Habitat, Ecology and Behavior Sulawesi warty pigs
are reported to occur in a wide variety of habitats, ranging from rainforest
and swamp, to open grasslands and agricultural areas, and at all altitudes up
to moss forest (>2,500 m) (MacKinnon, 1981). They usually live in groups,
but the social composition of these groups is not known (Macdonald, 1991).
They forage during the day, this activity being concentrated in the early
morning and evening. Although roots, fallen fruit, leaves and young shoots
constitute the bulk of their diet, invertebrates, small vertebrates and
carrion are also eaten (National Research Council, 1983). The pregnant sow
reported from south Sulawesi by Sody (1941) was probably mated in February.
Birth can occur at any time throughout the year but sows usually have their
young in April or May (National Research Council, 1983). Gestation length is
not known for certain, and the suggestion that it may lie between 16 and 20
weeks should be treated with the caution implied by Sody (1941). Farrowing
sows give birth in nests made of grasses, leaves, branches and twigs, piled
over a shallow excavation of approximately 2 m in length. Litter size ranges
from 2-8 (National research Council, 1983), but a recent study in North
Sulawesi found 6 pregnant sows killed by hunters to be carrying only 1-3
fetuses with a mean of only 2.17 fetuses per pregnancy (Budiarso et al., 1991). The young are striped
along the length of their bodies but lose these markings as they get older
(Appelman, 1955; National Research Council, 1983; and pers. obs.). Threats to Survival S. celebensis is evidently highly
adaptable, and is thought to remain abundant through much of its former
range, despite changing land use and hunting pressure. Apart from man, it has
few if any important predators on Sulawesi and its offshore islands. Whilst it is not,
therefore, considered threatened over much of its range at the present time,
wide scale deforestation for timber and conversion of land for agriculture,
coupled with human population expansion and immigration, have resulted in a
marked contraction of its range in some places. In addition, resources are
insufficient to enforce controls on hunting, and there are reports that
subsistence and/or organized commercial hunting is continuing even within
designated reserves and national parks (Smiet, 1982; Blouch, 1990). In north
Sulawesi, the Minahasa people consider wild pig meat to be superior to
domestic pork, and are willing to pay 20% to 50% more for it. Reports
obtained during brief surveys of three village markets in north-east
Sulawesi, suggest that butchers in each market handled from 2 to 20 wild pigs
per week, buying them live from commercial hunters and slaughtering them when
needed (Blouch, 1990). Budiarso et al.
(1991) recorded 2,317 pigs harvested in four regions of North Sulawesi during
12 months in 1990 and 1991. Although they found the fetal sex ratio to be
approximately 1:1, the male to female ration of 1:1.7 in harvested pigs
suggests that the females are more susceptible to these commercial hunting
operations, which may make heavily exploited populations especially
vulnerable to extirpation. The expansion of
human settlements also brings an increased threat of genetic contamination
and/or disease to the wild pig populations through the importation of
'improved' (ex-S. scrofa)
domesticates, and the carriage of these animals from coastal communities to
villages in the interior. Conservation Measures Taken Sulawesi warty pigs
are known or are likely to occur in all of the principal national parks,
nature and game reserves on Sulawesi, including Lore Lindu (2,310 sq km),
Dumoga-Bone (3,000 sq km), Morowali (2,250 sq km) and many other smaller
sites. Within all of these areas the species is technically fully protected
by law, though it is certainly still hunted in some of these areas
(Setyodirwiryo, 1959). There are few recent
data on the distribution and numbers of S.
celebensis on Sulawesi and neighboring islands. However, preliminary
surveys conducted in 1991 in various locations north and south-west of
Kendari and within the Lore-Lindu, Dumoga-Bone and Morowali National Parks,
indicate that the species is still plentiful in these areas. However, the
socio-economic importance of these animals to local people, as well details
of their distribution and relative abundance in each of these areas and
elsewhere in Sulawesi will require further study. Captive Breeding The species has only
very rarely been kept in captivity outside its country of origin; and, as far
as is known, pure-bred animals have never been produced in captivity.
Unfortunately, only the male of the pair acquired by the Singapore zoo about
ten years ago appears to have been pure S.
celebensis, and although these animals have produced several litters,
various domestic traits (including piebald markings and curled tails) are
evident in their progeny. At present there
seem to be no other individuals of this species held in zoological
collections elsewhere, though wild-caught piglets are kept by villagers in
Sulawesi. These animals are usually raised to slaughter weight and eaten or
sold in local markets (Blouch, 1990). Longevity is not known in the wild
population, but in captivity, animals have lived longer than 9 years. Additional Remarks S. celebensis is somewhat
variable in size and other characters, a circumstance, which led Groves
(1981) to treat the species as monotypic, and to reject a number of
previously recognized subspecies. However, Groves also drew attention to the
existence of three skulls from Latimojong Mountains in South Sulawesi, which
may represent a distinct form. These skull are of relatively small size for
this region, i.e. there being evidence of a north (smallest) to south
(largest) cline in body size on Sulawesi (which also extends to the offshore
island populations - see also Groves and Grubb, this vol.). Sulawesi and associated
islands comprise the larger (southern) section of the Wallacian sub-region,
which also includes the eastern Philippines. Sanborn (1952) included the wild
pigs of the eastern Philippines with S.
celebensis. This treatment was followed by various authors (e.g. Sinha,
1982; and Catibog-Sinha, 1985), but strongly refuted by Groves (1981) and
Groves and Grubb (this vol.) who demonstrated that these animals were more
closely related to the (Sundaic) S.
barbatus. This view is followed here, though the close resemblance of at
least some of the Philippine pigs (especially those from Luzon; to S. celebensis suggests that further
investigation of their affinities is warranted. Conservation Measures Proposed:
An Action Plan S. celebensis is of particular interest
in that it is the only pig species, apart from S. scrofa, which has been domesticated and quite widely
transported by human agency outside its original range. The available
evidence indicates that it is still maintained as a domesticate in some areas,
but its commercial importance and future potential as a genetic resource are
virtually unknown. Detailed studies of its ecology, behaviour, physiology and
regional genetic variation have yet to be undertaken, and although its
apparently large population size suggests it is not seriously threatened at
present, the small amount of available data is mostly anecdotal. This lack of
substantive data is presumably due to the relative remoteness of Sulawesi and
its offshore islands, which have only recently become more accessible. The
increasing interest in the renewable resources of this region should include
studies of these animals, which have long been of great economic importance
to the local people. Objectives 1. To promote field studies relevant to an
enhanced understanding of the biology and future management of this poorly
known species. 2. To conduct studies of its socio-economic
significance amongst societies of different ethnic origin and its potential
as a genetic resource for further domestication and development. 3. To investigate its regional genetic
variation with particular reference to the identification (and, if necessary,
the protection) of any possibly distinct forms, its affinities to other Asian
warty pigs and the origins and relationships of surviving domestic and feral
populations. Priority Projects: 1. Conduct status
surveys in selected areas within its original known range. Although
detailed, island-wide surveys would be impractical and possibly unjustified
on the basis of the present known status of this species, there is a need to
assess, or reassess, its conservation and taxonomic status in certain
locations, such as the Latimojong Mountains and elsewhere in south Sulawesi,
and on Selayar and other offshore islands where the species is known to have
occurred. In north Sulawesi, the extent of market hunting and its effects on
the wild populations needs to be determined with a view to ensuring that the
species is managed on a sustained yield basis. 2. Conduct surveys
in selected areas where the species is known or believed likely to have been
introduced. Efforts
should be made to establish the present status, human utilisation and
affinities of the various introduced wild (i.e. unmodified), feral or
domestic S. celebensis populations
in the Mollucas, Lesser Sunda Islands and the west Sumatran islands of
Simeulue and Nias (Oliver and Brisbin, this vol.). These studies are of
considerable anthropological interest, and can be expected to throw light on
the origins and affinities of these animals (and hence also the people who
introduced them), as well as the history and process of animal domestication.
In addition, some of these pig population are likely to be of some potential
genetic importance for the production of improved breeds, and efforts may
need to be made to preserve some pure-bred stocks (e.g. from genetic
contamination by hybridization with more modern domesticates of S. scrofa origin). 3. Promote studies
of the biology of this species, with particular reference to its behaviour
and ecology. Very
little is known about the natural history of S. celebensis, despite its evident importance as a basic economic
resource to a number of island and village societies. No detailed studies of
its behavioral ecology, diet, reproductive biology, parasites and diseases
have ever been published. Such studies should also investigate hunting
pressures and practices, and the relative densities of these animals in
intact and degraded habitats, with a view to assessing the impact of logging
and other sources of disturbance on their populations. 4. Promote the
establishment of captive breeding programmes for this species. Although
this species is not considered threatened at the present time, captive
breeding should be considered for several reasons: to stimulate local
interest in the species and its anthropological significance; to facilitate
an understanding of its biology; and to assist the development of management
techniques which may be of value to the commercial husbandry of the species. Acknowledgements A number of the
results reported in this paper were obtained during studies carried out with
financial support from the University of Edinburgh, the Wellcome Trust, The
Carnegie Trust for the Universities of Scotland, The Royal Zoological Society
of Scotland, the Pig Development Co., the Cotswold Pig Development Co. and
the Percy Sladen Memorial Trust, Trekforce, The British Council and the
Balloch Trust. The hospitality and kind assistance of the director and staff
at Singapore Zoo and the rectors and staff at the universities of Sam
Ratulang (Manado), Tadulako (Palu) and Haluoleo (Kendari) are also gratefully
acknowledged. William Oliver and Raleigh Blouch both provided useful comments
on earlier drafts of this text, and Paul Vercammen and Peter Cuypers kindly
prepared the distribution map. References Appelman, F. J. 1955. Über Sus celebensis
Müller & Schlegel. Zoologischer Garten 21: 152-156. Bell, J. 1987. Nutrition and reproduction of
Indonesian wild pigs. (Unpubl.) rep., Edinburgh University: 6 pp. Blouch, R. A. 1990. Report from the field:
Indonesia. Smithsonian Instit. Conserv. and Res. Centre Newsletter 1: 6-8. Bosma, A. A., de Haan, N. A., Blouch, R. A.
and Macdonald, A. A. 1991. Comparative cytogenetic studies in Sus verrucosus, Sus celebensis and Sus
scrofa vittatus (Suidae, Mammalia). Genetica 83: 189-194. Budiarso, Wilar, A. F., Tulung, B., Kaligis,
D. and Kaligis, W. A. A. 1991. The importance of Sulawesi wild pig (Sus celebensis) as a source of meat in
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11: 198-201 & 256-265. |
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