Pigs, Peccaries and Hippos Status Survey and Action Plan (1993)

Chapter 5.2

The Eurasian Wild Pig, Sus scrofa

William L. R. Oliver, I. Lehr Brisbin, Jr. and Shunjo Takahashi.

Status and Action Plan Summary

Status categories: all subspecies are 1-3 (widespread and locally abundant to potentially at risk), except riukiuanus which is 4 or 5 (which is vulnerable or endangered) according to population.

The Eurasian wild pig has one of the widest geographic distributions of all terrestrial mammals, and this range has been greatly expanded by human agency. The species now occurs in pure wild or barely modified feral form on all continents excepting Antarctica, and on many oceanic islands. It is the ancestor of most (but not all) ancient and modern domestic pig breeds, and there is evidence to suggest that it was independently domesticated in several different parts of its range, including S. E. Asia, the Far East and Asia Minor. As a wild form, it has constituted a primary resource of subsistence hunters since the earliest times, and it is one of the most important targets for recreational hunting wherever it remains sufficiently abundant. Over-hunting and changes in land use have resulted in the fragmentation of its range and its extermination throughout the British Isles, Scandinavia, parts of North Africa, and relatively extensive parts of its range in the (former) U.S.S.R. and northern Japan. Nevertheless, the species remains widely distributed and is often locally abundant. As a result of its depredations on crops it is regarded as a pest in many countries, where it remains unprotected outside designated wildlife reserves or is managed as a game animal.

Action plan priorities for this species focus on threats from habitat loss, over-hunting, disease and genetic contamination to the smallest and most threatened subspecies, S. s. riukiuanus. The Ryukyu wild pig is the only one of the (c. 16) recognized subspecies to be in included in the IUCN Red List, where it is presently accorded 'vulnerable' status. However, it is probably already 'endangered' on four (Ishigaki, Iriomote, Tokuno Shima and Okinawa) of the six islands on which it occurs, as a result of habitat loss, hunting pressure, hybridization with domestic pigs and introduced diseases. Other priority recommendations include the need for additional data on the distribution and status of certain other (less-known) subspecies, including a tentatively assigned form (subsp. nov.) from the central highlands of Sri Lanka; the resolution of questions relating to the genetic distinctness and range limitations of some of the continental races; and the ecological and genetic relationships between this and other species of Sus in those areas where sympatry occurs.

Introduction

S. scrofa is the antecedent of the overwhelming majority (but not all) domestic and feral pig populations. In its native form it has one of the largest ranges of any wild ungulate and, together with its domestic and feral derivatives, it has one of the most extensive distributions of all mammals. In different parts of this range it is naturally sympatric with at least three congenors (S. salvanius, S. barbatus and S. verrucosus), though it or its derivatives have been introduced by human agency into areas supporting all other (formerly allopatric) congenors (S. celebensis, S. cebifrons and S. philippensis) and non-congenors (Potamochoerus, Hylochoerus, Phacochoerus and Babyrousa), as well as the New World Tayassuids (Tayassu and Catagonus). Where introduced populations have become naturalized and abundant they are generally regarded as environmental pests (Oliver and Brisbin, this vol.), as well as posing a threat of disease contagion and/or genetic contamination to native suids, including endemic populations of this species (see later text).

S. scrofa has been studied extensively in Europe, North Africa and in the (former) U.S.S.R., and much comparable research has been conducted on the introduced, mostly feral, populations in the U.S.A., Australia and New Zealand (Briedermann, 1990). Available data indicate that the basic diploid number of 38 chromosomes (similar to domestic pigs) is found in eastern and south-east Asian populations, but this number decreases by Robertsonian translocations over the species' extensive range such that the continental European populations have only 36 chromosomes (Bosma et al., 1984). Eurasian wild pigs are also markedly variable in size, pelage and some other characters, and an enormous number of subspecies, and several different species, have been described. However, in a major review of the genus Sus, Groves (1981) argued that many of these named forms were synonymous or, in some cases were actually naturalized feral or hybrid (with S. celebensis) populations. Groves accordingly recognized only 16 subspecies, including a previously undescribed form, S. s. davidi, from Pakistan and north-western India, though he also drew attention to a small, as yet unclassifiable, skull from Central Province, Sri Lanka, which may represent another new subspecies. Only a few of the currently recognized subspecies, such as the insular taivanus (Taiwan) and riukiuanus (Ryukyu Is., south Japan), have clearly defined ranges, and precise data is lacking on the range limits/intergradation zones of many of the continental forms. Groves and Grubb (this vol.) have therefore distinguished four 'subspecies groupings', based on both geographic and morphological criteria, as follows:

1. 'Western races' of Europe (scrofa and meridionalis), North Africa (algira) and the Middle East (lybicus), extending at least as far east as Soviet Central Asia (attila and nigripes);

2. 'Indian races' of the Sub-Himalayan region from Iran in the west (davidi) to north India and adjacent countries as far east as Burma and west Thailand (cristatus), and south India and Sri Lanka (affinis and subsp. nov.);

3. 'Eastern races' of Mongolia and the Soviet Far East (sibiricus and ussuricus, Japan (leucomystax and riukiuanus), Taiwan (taivanus), to south-east China and Vietnam (moupinensis); and

4. 'Indonesian race' (or banded pig) from the Malay Peninsular, Sumatra, Java, Bali and certain offshore islands (vittatus).

Former and Present Distribution

S. scrofa is one of the most widely distributed terrestrial mammals, and has by far the largest range of all suiformes. It occurs throughout the steppe and broadleaved forest regions of the Palaearctic, from western Europe to the Soviet Far East, extending southwards as far North Africa, the Mediterranean Basin and the Middle East, through India, Indo-China, Japan (including the Ryukyu Chain), Taiwan and the Greater Sunda Islands of South-east Asia. Populations east of Bali are probably all introduced. It has been extinct in the British Isles since sometime in the 17th century, despite attempted introductions of new stock from Europe (Harting, 1880). It is also extinct in southern Scandinavia, over extensive portions of its recent range in west-central and eastern parts of the (former) Soviet Union (Heptner et al., 1961), and in northern Japan (Chiba, 1964, 1975). The species was last reported in Libya in the 1880's, and it became extinct in Egypt in about 1902 (Hufnagl, 1972; Fig. 10).

Link to Fig. 10: Approximate former and present distribution of the Eurasian wild pig Sus scrofa ssp. Modified after Heptner et al., 1961; Groves, 1981).

Habitat, Ecology and Behavior

The Eurasian wild pig occupies a wide variety of habitats, from semi-desert to tropical rain forests, temperate woodlands, grasslands and reed jungles; often venturing onto agricultural land to forage. The species is omnivorous, though stomach and fecal contents analyses indicate that vegetable matter, principally fruits, seeds, roots and tubers, constitutes about 90% of the diet (Spitz, 1986). A field study of the Indonesian wild pig, S. s. vittatus, in Ujung Kulon National Park in Java, indicated that these animals are predominately frugivorous, feeding on about 50 species of fruits, especially those of strangling figs (Ficus spp.), and that they are important seed dispersal agents (Pauwels, 1980). By comparison, analyses of the stomach contents of wild pigs (also S. s. vittatus) in agricultural areas of West Malaysia by Diong (1973), revealed that sugar cane, tapioca and rice were the commonest food items, but that usually more than one type of food had been eaten, even where a single cultivated crop was abundant. Other items commonly consumed by these pigs included soil, earthworms, roots and other vegetable matter and, in mangrove areas, mollusks, crabs and other arthropods and even fishes. The consumption of invertebrate and small vertebrate prey may be a necessary component of the diet, since a study of free-ranging domestic pigs in Papua New Guinea revealed that animals fed ad libitum lost weight when denied earthworms (Rose & Williams, 1983). In common with its feral derivatives (Oliver & Brisbin, this vol.), S. scrofa has also occasionally been reported to predate larger vertebrates, such as deer fawns and (tethered) goats (Hoogerwerf, 1970), though it is possible that such incidents involve only a few individuals in the population; an aspect also noted by Pauwels (1980) when referring to the predation of sea turtle nests by wild pigs in Udjung Kulon. Similarly, a large boar (S. s. cristatus) in Royal Chitawan National Park, Nepal, which was seen to displace an adult leopard from its kill, a domestic buffalo calf, which it then partly consumed (W. Oliver, pers. obs.), was reported by Park staff to regularly commandeer such kills, but that no other individual pigs had been seen to do this.

Wild pigs are normally most active in the early morning and late afternoon, though they become nocturnal in disturbed areas, where activity usually commences shortly before sunset and continues throughout the night. A total of 4 to 8 hours are spent foraging or traveling to feeding areas. Feeding is generally a social activity (even solitary males may join feeding groups) which also provides an opportunity for display and other agonistic behaviors (Beuerle, 1975). Radio telemetry studies in southern France indicate that they generally travel between 2 and 15 km per night, though this is often within an area of only 20 to 150 ha. However, the home range estimates for adult females and adult males over a 2-3 month period varied from 500-1,000 ha and 1,000-2,000 ha, respectively. During this same period, subadults covered an area of 500- 5,000 ha, and after 6 to 12 months they may have covered more than 10,000 ha; the larger home ranges of these animals being related to their expulsion from their natal groups and then undergoing a wandering phase. Movements over long distances (50 to 250 km) have also been recorded in Europe, but the extent and purpose of these movements has yet to be studied (Spitz, 1986). Experiments in which tagged animals are released and subsequently recovered provide evidence that they disperse freely over even larger areas (500 to 750 km2), which may also indicate the area occupied by large population units. The density of free-ranging S. s. scrofa in Europe rarely exceeds 5 individuals/km2 (Spitz, 1986), though much higher concentrations have been reported elsewhere, e.g. 27-32/ km2 on Peucang Island in Ujung Kulon National Park, Java (Pauwels, 1980) and 32.2-72.1/km2 in sugarcane areas in the Punjab, Pakistan (Shafi & Khokhar, 1985).

Wild pigs are gregarious, forming herds or 'sounders' of varying size depending on locality and season, but usually of between 6-20 individuals, though aggregations of over 100 have been reported (Prater, 1971; Legakul & McNeely, 1977; Briedermann, 1990)). The basic social unit is a nucleus of one or more females and their last litters. Animals peripheral to this comprise subadults from previous litters, and adult males during the mating season. However, the latter tend to stay in relatively close contact with 1 or 2 female groups at other times of the year, and subadult males or mixed sex groups of subadults may also form longer-term associations (Spitz & Janeau, 1990). The dynamics of the basic group include the isolation of the preparturient female, her re-entry with young, entry of nulliparous females, the arrival of adult males with the simultaneous departure of subadult animals (Spitz, 1986). In contrast to its domestic derivatives, reproductive activity in S. scrofa tends to be seasonal and positively correlated with the relative availability of principal foodstuffs or related climatic factors. In tropical countries, such as Sri Lanka, peak estrus activity has been recorded during the wettest months of November and December (Santiapillai and Chambers, 1980). However, social organization may also play a role in modulating the timing of reproductive events, since farrowing is often synchronized amongst females in the same social groups, which suggests a mechanism for synchronizing the onset of estrus (Spitz, 1986).

Wide fluctuations in the numbers of animals killed by hunters, particularly in the (former) U.S.S.R. and in France, suggest cyclic changes in the numbers of wild pigs available for hunting. Annual recruitment into the total population depends on reproductive rate (i.e. the number and prolificacy of females) and juvenile mortality, both of which factors may be influenced by the availability of foodstuffs and other external factors (Spitz, 1986). In western Europe, litter size is usually between 4 and 7 piglets (Briedermann, 199), though Harrison and Bates (1991) cite reports of 5 and 7-10 piglets per litter as being usual in Iraq and Armenia, respectively. Pauwels (1980) recorded an average litter size of 6-10 piglets at the beginning of the breeding season in Java, but this number dropped to only 2-4 piglets per litter towards the end of the breeding season. In the Ryukyu Islands, S. Japan, there is evidence that the wild pigs (S. s. riukiuanus) have two breeding seasons per year, though it remains uncertain whether individual sows normally produce litters twice a year (Yasuma, 1984). Juvenile mortality averages 15% in the first three months in western Europe, though between 50% and 75% mortality have been reported by the end of the first year of life (Jezierski, 1977; Briedermann, 1990). These mortality rates are thought to be highly dependant on such external factors as predation and climatic hazards, at least in wilderness areas (Spitz, 1986). Similarly, Pauwel (1982) suggested that the principal causes of juvenile mortality in wild pigs in Ujung Kulon were predation (particularly as a consequence of the accidental separation of infants from their mothers), along with differences in the relative rate of development of litter-mates and various parasite-related causes. These factors resulted in only about 15% of all progeny surviving to independence.

Threats to Survival

Habitat destruction and hunting pressure, either for food, sport or in reprisal for crop damage, are the principal threats to this species, particularly in areas near human habitation. In Afghanistan, Hassinger (1970) cited reports of the decrease in the numbers of wild pigs in the Pul-i-Khumri District in the 1950's as a result of the draining of marshlands for agricultural purposes and hunting by Europeans; but noted that they were still numerous in other districts where: "they invade the fields and cause serious damage during the harvest". In parts of Perak and Johore in West Malaysia, Diong (1973) reported that the numbers of wild pigs (S. s. vittatus) had diminished drastically as a result of increased hunting pressure, particularly for commercial purposes, and that most hunting methods, whether with guns, dogs or snares, was entirely non-selective. Nonetheless, wild pigs are still included in Malaysia's 'Agricultural Pest Ordinance, 1977', on account of their damage to a variety of crops, including sugar cane, tapioca, rice and even coconuts. Lay (1967) also remarked upon the damage to crops by wild pigs in Iran which: "...brings great wrath upon them, usually ineffectual, from the local farmers". In Pakistan, the expansion of the sugar cane industry in the 1960's and early 1970's brought about local increases in the numbers of wild pigs (S. s. davidi), whose depredations in the cane fields (estimated at an annual loss rate of Rs.5 million in 1978) led to the development of control measures, including the use of poison baits (Shafi & Khokhar, 1985).

Although actually referring to wild pigs in India, it is clear that Prater's (1971) opinion that: "No animal is more destructive to crops and, in cultivated areas, it is impossible to make a plea for its protection", would find popular support in many other countries. In the Ryukyu Islands, S. Japan, the endemic S. s. riukiuanus is actively regarded as an environmental pest, and bounties are paid to farmers for killing them by the Japanese Government, despite the fact that this taxon is recognized internationally as being seriously threatened throughout it extremely restricted range (see later text). In various places in Indonesia, most notably in Java, deliberate attempts have been made in the past to eradicate wild pigs altogether by means of organized shooting parties and poisoning campaigns. However, despite many thousands of wild pigs being destroyed in this way, it is clear that this has had little lasting effect on these animals which, according to Hoogerwerf (1970), have: "remained further removed from extinction than any other species of game in Java". This situation evidently obtains in a number of other countries, including Vietnam (R. Ratajszsak, pers. comm.) and Taiwan (K. Newell, pers. comm.), where wild pigs are reported to survive in a number of nominally protected areas where all or most of the other principal 'game' species have been eradicated by sustained hunting pressure.

In these and many other (non-Islamic) countries or local communities, wild pigs often constitute the single most important game animal to subsistence and/or recreational hunters. Sport hunting accounts for about 30 to 50% of animals heavier than 20 kg in southern France, though this figure may be as high as 50 to 75% in some heavily populated countries, where hunting remains largely or wholly uncontrolled (Spitz, 1986). For example, the wild pig population inhabiting the 25,000 ha of broadleaved woodlands around Monticiano in Italy, has apparently been able to sustain its numbers despite an annual hunter-kill rate of about 50% (c. 500 animals) of the population (Devitt, 1984).

According to figures produced by the Japanese Environment Agency a total of 1,279,453 (or x 63,973 per annum) wild pigs were harvested in Japan between 1970 and 1989 (incl.), of which 1,083,858 (85%) were taken by hunters, and the remaining 195,596 were destroyed as crop pests during the closed season. The great majority of these animals are S. s. leucomystax from the main islands of Honshu, Shikoko and Kyushu, and this subspecies is evidently able to withstand high levels of harvesting to judge from contemporary reports of marginal expansions in the overall range of this subspecies (Hanai, 1982; Takahashi, 1980). Unfortunately, however, these totals do not differentiate between the numbers of S. s. leucomystax and those of S. s. riukiuanus from the three small islands of Amami Oshima, Tokuno Shima and Kakeroma Jima, which are also included in these figures. As previously indicated, the latter subspecies is declining rapidly in numbers on these islands, and on the neighboring island of Okinawa, largely as a result of over-hunting (Barber et al., 1984; H. Obara, pers. comm.). This conclusion is also borne out by official figures on the annual harvest of S. s. riukiuanus from two other islands, Iriomote and Ishigaki, in the Ryukyu chain between 1965 and 1981, which indicate a downward trend in the numbers of these animals (Yasuma, 1984) and a marked increase in the amount of effort required by local hunters to obtain smaller catches (Hanai, 1982). Nonetheless, according to these figures an average of 530 and 190 wild pigs were still being taken annually on Iriomote and Ishigaki, respectively; of which slightly more than 50% were killed as 'agricultural pests', i.e. mostly out of season, often with a Government bounty being paid. Moreover, it is certain that these totals are a serious underestimate - perhaps by as much as 50-100% - of the actual numbers killed, since many hunters operate without licenses and do not declare their catches (Barber et al., 1984; Yasuma, 1984). Formerly, virtually all of these pigs were consumed locally but, following the restoration of electricity (and, hence, refrigeration) in 1972, commercial traders began operating on the islands, and the majority of carcasses are now exported to gourmet markets in Osaka, where they realize relatively high prices and ensure a continued demand for wild-caught meat (Yasuma, 1984).

Wild pigs are also susceptible to a variety of highly contagious diseases which can decimate their populations. Santiapillai et al. (1991) referred to a catastrophic crash in the wild pig population of Ruhuna National Park in Sri Lanka in 1989 owing to an outbreak of swine fever, but that population numbers had apparently recovered by June 1991. Many wild pigs are also reported to have died during an outbreak of disease in the Kanto Region on Honshu Island, Japan in 1877 (Yanagida, 1913). It is possible that this was hog cholera, contracted from domestic pigs which were imported to the region at that time (Chiba, 1975), and this may have been one of the factors contributing to the extirpation of S. s. leucomystx throughout the north of their range on this island (Fig. 10). An outbreak of severe skin disease (tentatively identified as sarcoptic mange) on Iriomote, which was first noted in 1976, had spread throughout the Island by 1980, and infected up to 83% of the S. s. riukiuanus population according to data based on hunter-killed samples (Yasuma, 1984).

The Ryukyu pigs are also threatened by genetic contamination through contact with free-ranging domesticates. On Ishigaki Island, interbreeding with domestic pigs has been so prevalent that it is doubtful if the remaining wild stock can be considered genetically pure (Obara, 1982). Moreover, it is unlikely that this problem will be confined to Ishigaki, given that the meat from wild x domestic hybrids or 'ino-buta' is popular and local farmers will continue to produce it. Indeed, ino-buta have been farmed commercially on Iriomote for many years, often in poorly controlled conditions. As a result, feral ino-buta have become established on the adjacent, smaller islands of Sotobanare and Uchibanare, and it is claimed that a number of these animals have crossed onto Iriomote at low tide; thereby posing a further, serious threat to the remaining wild stock there (Yasuma, 1984; Takahashi & Tisdell, in press).

Similarly, Genov et al. (1991) reported that the traditional practice of rearing 'domestic' pigs in semi-wild conditions in Bulgaria has resulted in their hybridizing with the wild boar populations in the eastern and north-eastern parts of that country, and that genetically pure wild boars now occur only in the Rila-Pirin-Rhodopes Mountains in the south of this country, where domestic pigs are not reared in the wild. The principal threat to the survival of the Monticiano population in Italy, lies not so much with the high annual hunter-kill rate but with the fact that the genetic integrity of the native population has been seriously compromised by the introduction of Central European boars after World War II, which have interbred with these animals. Indeed, the introduction of non-native wild pigs, by hunting interest groups in the belief that these were more desirable because of their larger size and reputed greater fecundity, has been so widespread in Italy that the only surviving pure-bred native stock is thought to be in the presidential reserve in Castel Porziano, near Rome (Devitt, 1984).

Conservation Measures Taken

Generally, few, if any, practical measures have been taken in any country for the specific purpose of conserving wild populations of any subspecies of S. scrofa, except in the sense of maintaining stock levels for hunting, particularly for sport hunting. Thus Genov et al. (1991) reported a gradual increase of the wild boar population in Bulgaria in the late 1950's following legal measures to regulate hunting, and because of the reintroduction of animals from breeding farms in the north-east of the country, in the Balkan Range and Sredna Gora. Even in this instance, however, other factors may also be operating, since similar increases in the local wild pig populations in Spain, France, Switzerland, Czechoslovakia and eastern Russia have been described by Sáez-Royuela & Tellería (1986), who simply attributed this trend to a progression to a more temperate climate and, hence, progressively milder winters of benefit to these animals.

Somewhat ironically, local wild pig populations are also reported to be increasing in numbers in several countries as a consequence of the spread of Islam. For example, the north-west African race, S. s. algira, although extinct in Libya, is thought to be expanding in neighboring Algeria where it is designated a game animal but, as the meat is now seldom eaten in this country, hunting pressure has been greatly reduced since colonial times (Kowalski & Rzebik-Kowalski, 1991). These authors also cite earlier reports of wild boars hybridizing with domestic pigs, but the latter are no longer kept in Algeria.

As previously stated, S. s. riukiuanus has been included in the IUCN Red List since 1982, where its 'vulnerable' status reflects a widespread concern about the environmentally destructive development of the Ryukyu Islands and the growing number of threats to the ecosystems and endemic species of Iriomote and other islands in this region. In 1978, these concerns led to the passing of a resolution at the 14th IUCN General Assembly in Ashkhabad, which called upon the Government of Japan to take immediate steps to ensure the conservation of Iriomote Island and its endemic taxa, and for the subsequent designation of the whole of the Nansei Shoto Region (often referred to as the 'Galapagos of the East' on account of the high percent endemicity of its fauna and flora) as a bio-geographical priority region in the World Conservation Strategy. In 1982, the 'Nansei Shoto Conservation Project' was launched by WWF-Japan, with initial emphasis being placed on the conduct of wildlife and socio-economic surveys on Iriomote and Amami Oshima (Obara, 1984a,b). In the interim, however, the desired increased protection of the Nansei Shoto Region was clearly at odds with the Japanese Government's regional policies, and the development of the islands continued - a circumstance which led to the passage of a another resolution, condemning Japan's treatment of the region, at the 16th General Assembly of IUCN in Costa Rica in 1986. Unfortunately, this also appears to have had little affect, as evinced by further major development plans, including the controversial Ishigaki Airport extension, and recent plans to construct a new dam and road on Iriomote Island. Although one third of Iriomote has been designated as a national park, the proposed road will cut through the park and will also increase access by poachers who have already reduced the wild pig to less than half of its numbers before the park was created (Brazil, 1988).

Captive Breeding

Of all wild pigs species, S. scrofa is by far the most widely maintained and bred in captivity, though general perceptions about the relative abundance of this species has resulted in diminished interest in its propagation. Many zoos, particularly in western Europe, have therefore disposed of their stocks of these animals, mostly to 'wild boar breeding farms', which have escalated in number to meet growing demands in the gourmet meat markets and for commercial diversification. In addition, increasingly restrictive quarantine and other veterinary regulations appertaining to the international movements of all live suids, has made it extremely difficult to establish new breeding programs.

Contrarily, since these animals are most easily acquired in their countries of origin, local stocks are most likely to be pure-bred and, hence, most valuable for research and conservation purposes. In this situation, priority should be given to the establishment of national or regional breeding programmes for each of the rarest subspecies, especially S. s. riukiuanus. Unfortunately, although there were at least 13 (6 males, 7 females) individuals of this subspecies were in captivity in Japan in 1990, these were located in five separate collections, and there is still no coordinated plan for its long-term management on either a national or international scale (JAZGA, 1990).

Conservation Measures Proposed:

An Action Plan

As a general rule, S. scrofa is both highly adaptable and highly resistant to a variety of degradative processes, and may thrive under conditions of habitat modification and hunting pressure which have devastated other forms of wildlife. In addition, most subspecies are well represented in protected areas in their relatively extensive ranges. Nonetheless, there are reasons for concern about a number of distinct populations of S. scrofa, of which the Ryukyu pigs are undoubtedly the most seriously threatened. Indeed, riukiuanus is the only subspecies of S. scrofa to be included in the IUCN Red List of Threatened Animals (IUCN, 1990), where it has been accorded the status of 'vulnerable' since 1982, but is already thought to be 'endangered' on at least four of the six islands in the Ryukyu Chain which constitute its entire, and therefore extremely restricted, range. This particular form is also the most distinct, and (with an average adult male body weight of only about 45 kg; Barber et al., 1984) by far the smallest, subspecies. It is therefore of some interest as a potential genetic resource, as well as being one of the principal 'flagship' animals for increased conservation activity in the crucially important Nansei Shoto Region. For all of these reasons, the following recommendations are mostly confined to the immediate and longer-term management requirements of this taxon.

Objectives:

1. To promote local interest in, and the enhanced future protection and management of, the Ryukyu Islands' dwarf wild pig, S. s. riukiuanus, and any other threatened native subspecies may be identified in the future;

2. To promote further applied research on the taxonomy, distribution, conservation status and biology of the species, particularly the least known forms;

3. To discourage any future releases of any specimens of any subspecies of this species, or its domestic and feral derivatives, outside their known former ranges, and encourage the eradication or control of such introduced populations as may exist at present; and

4. To investigate the cultural and economic significance of these animals to local people, particularly in S. E. Asia, and their potential genetic importance in terms of: a) possibilities for their further domestication and/or b) an enhanced understanding of the origins and relationships of present day domestic and wild populations.

Priority Projects:

1. Provide all appropriate support to any existing or proposed future conservation initiatives in the Nansei Shoto Region, relevant to the enhanced future management and protection of the Ryukyu Island's dwarf wild pig, S. s. riukiuanus.

Given the often highly politicized nature of conservation issues in this Region, and widespread governmental and local ambivalence, disinterest or even hostility towards the conservation needs of these animals, actions primarily directed towards their enhanced future protection are unlikely to engender local support over much of their remaining range (but also see below) and could well prove counter-productive. For these and other reasons, priority should be given to supporting programmes directed towards the conservation of biodiversity, which is, in any event, of obvious overriding importance.

2. Conduct (preliminary or repeat) status surveys on all (six) islands in the Ryukyu Group known to support remnant populations of S. s. riukiuanus (i.e. Iriomote, Ishigaki, Okinawa, Tokunoshima, Amamioshima and Kakerome), and implement emergent recommendations.

Recent data is lacking on the distribution, status and future management needs of these animals on each of these islands, but particularly Kakerome (a U.S. Naval Base) and Tokunoshima which are not known to have been surveyed in this context. Any such surveys should also try to assess current local attitudes to these animals, current population trends, the extent of domestic consumption versus commercial trade in the flesh of these animals and the hybrid 'inobuta', the level of hybridization/genetic purity of each population (i.e. from interviews and the collection of blood and other tissue samples from hunter-killed specimens for comparative molecular genetic studies of populations on each of these islands, the status of existing protected areas (if any) and options for the enhanced future protection of representative populations on each island, etc. A special effort should also be made to alert the U.S. Navy to the biological importance of the forested lands under their jurisdiction on Okinawa and Kakerome, and to enlist the support of that authority in the implementation of recommendations for the future protection and benign management of these habitats and species.

3. Promote development of a coordinated breeding programmed for S. s. riukiuanus, both nationally and internationally.

Despite international recognition of their precarious status, there has been a perplexing and regrettable lack of interest within the Japanese zoo community to develop any coordinated breeding program for these animals. In fact, a reasonable number of potential founders already exist in a few collections in the country, some of which are breeding these animals, but further, concerted efforts should be made to encourage those collections to collaborate in the development of such a program and to extend this program to other reputable collections elsewhere - preferably under the aegis of a structured 'conservation education and research program' in the best interests of these animals and the issues they represent.

4. Collect, evaluate and disseminate data on the taxonomic relationships, distribution and conservation status of other, less-known forms, with a view to the resolution of certain outstanding taxonomic problems and the development of recommendations for their enhanced future protection, if so required.

Additional data is needed on the distribution and status of some, poorly-known subspecies and populations, including a tentatively assigned form (subsp. nov.) from the central highlands of Sri Lanka and the insular taivanus (Taiwan). Efforts should also be made to resolve outstanding questions relating to the genetic distinctness and range limitations of many of the continental races, which are poorly understood at present.

5. Promote further research on the biology and ecology of all less-studied populations, particularly those in extreme habitats, or in areas of sympatry with other species of Sus.

Most of the information on this species has originated from studies conducted in Europe or on the feral populations in the U.S.A., Australia and New Zealand. Priority should therefore be given to studies of other populations elsewhere, particularly those in semi-desert regions or other extreme habitats, and/or studies focused on the ecological and genetic relationships between this and other species of Sus in those areas where sympatry occurs (e.g. with S. barbatus in the Malaysian Peninsular and Sumatra, and with S. verrucosus on Java).

Acknowledgements

The authors are grateful to John A. Burton, Peter Grubb, John J. Mayer, Francois Spitz and Alastair Macdonald for their helpful input and suggestions on various drafts of this paper, and to Paul Vercammen and Peter Cuypers for their patience and assistance in preparing and updating the distribution map. I.L.B's contribution to the preparation of this Plan was supported in part by a contract (DE-AC09-76SR00-819) between the United States Department of Energy and the University of Georgia.

References

Barber, G., Horne, L., Mason, M. and Perkins, P. 1984. Nansei Shoto Expedition, Japan: December 7th 1983 - January 10th 1984. (Unpubl.) report: 52 pp.

Beuerle, W. 1975. Frielanduntersuchungen zum kampf-und sexualverhalten des Europ„ischen wildschweines (Sus scrofa L.). Zeitschrift Tierpsychologie 39: 211-258.

Bosma, A., De Haan, N. A. and Macdonald, A. A. 1984. Karyoptype variability in the wild boar (Sus scrofa). Symposium International sur le Sanglier, Toulouse 1984. Colloque de l'INRA No 22: 53-56.

Brazil, M. 1988. Japan's string of pearls loses its lustre. New Scientist 117 (1,606): 47-51.

Briedermann, L. 1990. Schwarzwild. VEB Deutscher Landwirtschaftsverlag, Berlin: 540 pp.

Chiba, T. 1964. Geographical distribution of wild boars and deer in the Japanese Islands and their areal and quantitative fluctuations (in Japanese). Geographical Rev. 37 (11): 575-592.

Chiba, T. 1975. Distributions of large wild mammals and their changes in the eastern foot of Mt. Zao, Miyagi Prefecture, northern Honshu (in Japanese). Annals. Tohoko Geog. Assoc. (Tohoko Chiri), 27 (2): 74-81.

Devitt, J. 1984. All-Italian boars. BBC Wildl. Mag., December 1984: p. 604.

Diong, C. H. 1973. Studies of the Malayan wild pig in Parak and Johore. Malay. Nat. J. 26: 120-151.

Genov, P., Nikolov, H., Massei, G. and Gerasimov, S. 1991. Craniometrical analysis of Bulgarian wild boar (Sus scrofa) populations. J. Zool. Soc. Lond. 225: 309-325.

Groves, C. P. 1981). Ancestors for the Pigs - Taxonomy and Phylogeny of the Genus Sus, Tech. Bull. No. 3., Dept. of Prehistory, Australian National Univ. Press, Canberra: 96 pp.

Groves, C. P. and Grubb, P. (this vol.). The Eurasian wild pigs, Sus and Babyrousa: taxonomy and description.

Hanai, M. 1982. Fluctuations in numbers of Ryukyu inoshishi (wild pigs). (Unpubl.) ms.: 13 pp.

Harrison, D. L. and Bates, P. J. J. 1991. The Mammals of Arabia (2nd Ed.). Harrison Zoological Museum, Sevenoaks, United Kingdom, xvi+ 354 pp.

Harting, J. E. 1880. British Animals, Extinct within Historic Times. Tr�bner & Co., London: pp. 77-114.

Hassinger, J. D. 1970. A survey of the mammals of Afganistan. Fieldiana Zool. 60: p. 163.

Heptner, V. G., Nasimovich, A. A. and Bannikov, A. G. 1961. Artiodactyla and Perissodactyla. Vol. 1, 1147 pp., in: V. G. Heptner and N. P. Naumov (eds.): Mammals of the Soviet Union, Vysshaya Shkola Publishers, Moscow (English translation, 1988, Smithsonian Institution Libraries and The National Science Foundation, Washington D. C.).

Hoogerwerf, A. 1970): Udjong Kulon. The Land of the Last Javan Rhinoceros. E. J. Brill, Leiden, Netherlands. Hufnagl, E. (1972): Libyan Mammals. Orleander Press: p. 48.

I.U.C.N. 1990. IUCN Red List of Threatened Animals. IUCN, Cambridge and Gland: p. 26.

JAZGA 1990. Japanese Association of Zoological Gardens and Aquariums (JAZGA). Ann. Rep. 1989.

Jezierski, W. 1977. Longevity and mortality rate in a population of wild boar. Acta Theriologica 22/24: 337-348.

Kowalski, K. and Rzebik-Kowalski, B. 1991. Mammals of Algeria. Polish Academy of Sciences, Warsaw: 186-189.

Lay, D. M. 1967. A study of the mammals of Iran. Fieldiana Zool. 54: 1-282. p. 223.

Lekagul, B. and McNeely, J. A. 1977. Mammals of Thailand. Kurusapha Ladprao Press, Bangkok: pp. 661-664.

Obara, H. 1982): The present status of the Iriomote dwarf hog. (Unpubl.) ms.: 2 pp.

Obara, H. 1984a. Nansei Shoto Conservation Project by WWFJ. In: Conservation of the Nansei Shoto: Part I, WWF Japan Scientific Committee. World Wildlife Fund Japan: pp. 1-2.

Obara, H. 1984b Conservation issues in Japan. IUCN: Species Survival Commission Newsletter 3: 9-10.

Oliver, W. L. R. and Brisbin, I. L. (this vol.) Intoduced and feral pigs: problems, policy and priorities.

Pauwels, W. 1980. Study of Sus scrofa vittatus, its ecology and behaviour in Ujung Kulon Nature Reserve, Java, Indonesia. (Unpubl.) Ph.D. thesis, Univ. of Basel, Switzerland.

Prater, S. H. 1971): The Book of Indian Animals. Bombay Nat. Hist. Soc., Bombay: 299-300.

Rose, C. J. and Williams, W. T. 1983. Ingestion of earthworms, Pontoscolex corethrurus, by village pigs, Sus scrofa papuensis, in the highlands of Papua New Guinea. Applied Animal Ethology 11: 131-139.

Sáez-Royuela, C. and Tellería, J. L. 1986. The increased population of wild boar (Sus scrofa L.) in Europe. Mammal Rev. 16 (2): 97-101.

Santapillai, C. and Chambers, M. R. 1980. Aspects of the population dynamics of the wild pig (Sus scrofa, Linnaeus 1758) in the Ruhana National Park, Sri Lanka. Spixiana 3 (3): 239-250.

Santiapillai, C., Dissanayake, S., Sumanasena, A. H., Padmasiri, U. Wijesinghe, G., Jaymane, H. P. and Badaranaike, C. 1991. Population structure, activity and density of the wild pig (Sus scrofa) in the Ruhuna National Park, Sri Lanka. W.W.F.- 3988 Project Report Asia: conservation of large mammals, August 1991 (unpubl.): 9 pp.

Shafi, M. M. and Khokhar, A. R. 1985. Some observations on wild boar (Sus scrofa) and its control in sugarcane areas of Pujab, Pakistan. J. Bombay Nat. Hist. Soc. 83: 63-67.

Spitz, F. 1986. Current state of knowledge of wild boar biology. Pig News & Information 7 (2): 171-175.

Spitz, F. and Janeau, G. 1990. Spatial strategies: an attempt to classify daily movements in wild boars. Acta Ther. 35: 129-149.

Takahashi, S. 1980): Recent changes in the distribution of wild boars and the trade of their flesh in Japan. Geog. Sciences (Chiri-Kagaku), 34: 24-31.

Takahashi, S. and Tisdell, C. (in press) The feral and near feral animals of Iriomote Island: pigs, goats and cattle. Geog. Rev. Japan (Series B), 65 (1).

Yanagida, K. 1913. Changes in distribution of wild animals (in Japanese). The Collected Writings of Yanagida Kunio, 24: p. 416.

Yasuma, S. 1984. The Iriomote wild pig in danger of extinction (August 1982 Survey). In: Conservation of the Nansei Shoto: Part I, WWF Japan Scientific Committee. World Wildlife Fund Japan: 177-185.

Back to Contents

Next: Chapter 5.3 – The Pygmy Hog

Back to PPHSG homepage