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

Chapter 5.6

The Philippine Warty Pigs

(Sus philippensis and S. cebifrons)

William L. R. Oliver, C. Roger Cox and Colin P. Groves.

Status and Action Plan Summary

Status categories 3 & 5 - the (east) Philippine warty pig, S. philippensis, is rare and the (west-central) Visayan Islands' warty pig, S. cebifrons, is endangered.

Recent taxonomic reviews have revealed that there are 3 species and (at least) 2 subspecies of wild pigs in the Philippines, of which 2 species and 1 subspecies are endemic. This is a larger number of endemic suid taxa than any other country, with the exception of Indonesia. Unfortunately, however, the generally extreme levels of deforestation on most islands on which they occur, coupled with intense hunting pressure, inadequate legal protection and the poor enforcement of existing legislation even within most protected areas, have resulted in the systematic decline of all Philippine populations of these animals.

These factors are especially apparent in the (west) Visayan region, where the endemic warty pig, S. cebifrons, is already extinct or close to extinction on five of the seven islands (Masbate, Guimaras, Cebu, Sequijor and Bohol) in which it is known or believed to have occurred, and now survives only in a few small, isolated areas on Negros and Panay, where all remaining populations are still hunted intensively. By comparison, S. philippensis remains relatively widely distributed in most still-forested areas on the larger islands of Luzon, Mindoro, Samar, Leyte and Mindanao, where it occurs in all of the principal national parks. It probably also still occurs on a number of the smaller islands within the Luzon and Mindanao Faunal Regions.

At present, wild pigs are unprotected outside designated reserves and national parks and there are no effectively protected areas within the limited, and extremely fragmented, remaining range of S. cebifrons. Immediate action is required to address this situation and to establish a properly structured captive breeding programme as a safeguard against its possible early extinction in the wild state. In view of the essentially negative attitudes of local people to wild pigs, a conservation education programme is proposed, and more basic research on various aspects of the distribution, status, biology and management of some of these animals should be actively promoted. Some priority is also given to the acquisition of specimen materials from selected locations in order to elucidate the systematic relationships of the principal insular populations of philippensis, which are more variable than is indicated by their present (monotypic) assignation, and to facilitate a definitive reassessment of the affinities of the eastern Philippine species with the other Wallacian (S. celebensis) and Sundaic (S. barbatus) forms.

Introduction

The wild pigs of the Philippines have generally been attributed to two, more widely distributed species, the bearded pig, Sus barbatus, and the Sulawesi warty pig, S. celebensis. Thus the wild pigs of the west Philippine islands of Balabac, Palawan and the Calamian Group, which form part of the Sunda Shelf, are most closely related to the bearded pigs of Borneo, Sumatra and the Malayan Peninsular, whilst those of the central (Visayas Islands) and eastern (Luzon, Mindanao and associated islands) Philippines, which form part of the Wallacian Region, were lumped with the Sulawesi pig (Sanborn, 1952).

In a major review of the genus Sus, Groves (1981) confirmed the close relatedness of the west Philippine pigs with S. barbatus, but reaffirmed their separation as an (endemic) subspecies, i.e. S. b. ahoenobarbus (see earlier text). However, Groves also argued that the affinity of the central and eastern Philippine pigs with S. celebensis was purely superficial, and that these populations were also more closely allied to S. barbatus. This view was later endorsed by Mudar (1986), who also concurred with Groves' conclusions that the central (Cebu and Negros) and eastern (Luzon, Mindoro, Mindanao and Jolo) Philippines populations were not only distinct from those of the western Philippines but were also distinct from each other. These regional populations were therefore (provisionally) reassigned as two separate subspecies of S. barbatus, i.e. S. b. cebifrons and S. b. philippensis, respectively. Even so, it was stressed that these were tentative assignations owing to the few museum specimens studied (particularly from the Visayas Region, where only two skulls were available for examination from Cebu, only one from Negros and none from the other Visayan islands of Guimaras, Panay and Masbate), and the complete absence of any comparative cytogenetic data, precluded a definitive assessment of the systematic relationships of these populations.

To a large extent this situation still obtains, though the recent acquisition of a series of skulls and mandibles from Negros (cebifrons) and Samar (philippensis), together with the first photographs revealing the external characters of Visayan animals, has revealed that the central and eastern Philippine pigs are sufficiently different from barbatus and from each other to warrant separation as distinct species; i.e. S. cebifrons and S. philippensis, respectively (Groves, 1991; Oliver, 1991, 1992). A description of these small (S. cebifrons) to medium (S. philippensis) sized pigs is provided by Groves and Grubb (this vol.), who treat both species as monotypic but acknowledge that S. philippensis appears to be regionally variable in some characters and may ultimately prove polytypic.

The recognition of (at least) 3 taxa of wild pigs, also means that the Philippines has a larger number of endemic suids than other country with the exception of Indonesia, which has (at least) 5 species and 8 subspecies, of which 3 species and 5 subspecies are endemic. The inclusion of pigs from Jolo in the Sulu Archipelago with S. (b.) philippensis (Groves, 1981) is also of interest in this context, since it implies the westward colonisation of these islands by wild pigs from Mindanao, rather than eastwards from the Bornean mainland (Sabah). There is no doubt that 'typical' bearded pigs (S. barbatus ssp.) also occur in the south-westernmost islands (Sibutu and Tawitawi) of the Sulu chain. There are numerous, apparently reliable, accounts of wild pigs crossing the channel between Sabah and Sibutu, where they have sometimes been killed by fisherman. An officer in the Philippine navy reported seeing some of these animals whilst on a tour of duty in c. 1970, and a large number of swimming animals are reputed to have been used for target practice by a U.S. Navy battleship, which encountered them whilst on patrol (R. Hilado, pers. comm.). It therefore seems likely that a fourth (non-endemic) taxon of wild pig, the Bornean S. b. barbatus, should be added to the Philippine list, and that the Sulu Archipelago has been colonised by different populations/taxa of these animals from the south-west (Sabah) as well as the north-east (Mindanao) (Fig. 14).

Link to Fig. 14: Presumed former and present known distribution of wild pigs in the Philippines.

Former and Present Distribution and Conservation Status

Wild pigs are known or reported from all of the larger, and many of the smaller, offshore islands in the Philippines. As previously indicated, their distribution may be divided into three broad regions, i.e.: 'Palawan' (including Balabac and the Calamians Group); the 'Visayas Islands' (comprising Negros, Cebu, Masbate, Panay and Guimaras, but not Samar, Leyte and Biliran - see below) and the larger, eastern islands of Luzon, Mindoro and Mindanao. Wild pigs are known to occur (or to have occurred until recently) on all of these islands and many of the smaller, offshore islands and island groups (e.g. the Sulu Archipelago; see Table 8).

Table 8. Present known distribution and status of wild pigs (Sus spp.) in the Philippines.

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Taxon Status Category Distribution

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S. b. ahoenobarbus 4: Rare and Balabac*, Palawan and Calamians (Busuanga, Culion and

(endemic ssp.) declining Coron Is.).

S. b. barbatus 2: Locally rare Sulu Archipelago* (Sibutu and Tawitawi only ?).

(non-endemic ssp.) but widespread in Borneo

S. cebifrons 5-7:Endangered Panay, Guimaras (extinct), Negros, Cebu (extinct) and

(endemic sp.) to Extinct Masbate*.

S. philippensis 3: Rare and Luzon, Catanduanes, Samar, Biliran, Leyte, Mindanao,

(endemic sp.) declining Jolo* and ? other islands*.

Sus spp/ssp. ? 3-6: Rare Mindoro (rare), Sibuyan (rare), Bohol (critical), Sequijor

to Extinct (extinct).

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Key: * = no recent data.

As indicated in Table 8, recent data on the wild pig populations on many islands, particularly the smaller islands, is lacking and their present status can only be inferred from the extent of remaining forest over their known ranges. Thus, S. b. ahoenobarbus is probably the most threatened subspecies of 'typical' (or Sundaic) bearded pig (see Caldecott et al., this vol.) and is 'presumed' to be at greater risk than S. philippensis, because it has a relatively smaller range and because the smaller, insular populations on the (now mostly deforested) islands of Balabac and the Calamians are most unlikely to remain securely established. This subspecies is thought to be still relatively widely distributed on Palawan, where it may even be locally common in some areas, but it is intensively hunted (McGowan, 1987 and pers. comm.) and the surviving forests on Palawan are being rapidly depleted by uncontrolled logging and agricultural encroachment (Quinnell and Balmford, 1988).

By comparison, S. philippensis has almost certainly been extirpated over a greater proportion of its former range than S. b. ahoenobarbus, but this range is also considerably larger and includes some still (relatively) extensive tracts of forest on the larger islands of Luzon, Samar, Leyte and Mindanao. On all of these islands the species is reported to remain quite widely distributed wherever significant amounts of forest remain. Far less forest remains on Biliran where, by 1985 (see below), the species was reported to declined to the point that viable populations were unlikely to survive for much longer. The species is also reported from Jolo and it is presumed to occur, or to have occurred formerly, on Basilan and on some of the other smaller islands in the Mindanao and Luzon faunal regions, but recent information from these areas is lacking. Wild pigs are reported to be survive on Sibuyan (S. Goodman, pers. comm.) and to be locally common in some still-forested areas of Mindoro (Rabor, 1986; Cox, unpubl.), though the identity of these animals are not yet known (Table 8).

The distribution and status of wild pigs on Samar, Leyte and Biliran were investigated during a field survey in the central Philippines in 1985. This was primarily intended to assess the status and future management needs of S. cebifrons and the Philippine spotted deer (Cervus alfredi), which were assumed to occur on these islands (Cox, 1985, 1987a). However, although all of these islands are included within the Visayas (geopolitical) Region, they are actually a northward extension of the 'Mindanao Faunal Region', as defined by Heaney (1986) on the basis of the 120 m bathymetric line (Fig. 14). Thus, although Cox's survey revealed that Samar and (to a lesser extent) Leyte continued to support the largest populations of wild pigs in the 'Visayan Islands', these populations are undoubtedly S. philippensis (as Groves has confirmed - see above), rather than S. (b.) cebifrons, as was assumed at the time (Oliver et al., 1991; Oliver, 1992).

The recognition that S. cebifrons is confined to the (west) Visayan Islands of Cebu, Negros, Guimaras, Panay and Masbate, profoundly influences any assessment of its conservation status. This taxon is undoubtedly more gravely threatened than previously supposed, or indicated by its current 'Vulnerable' designation in the IUCN Red list of Threatened Animals (IUCN, 1990). As it is, the species is certainly 'Endangered' according to the terms of these status categories. The reasons for this are based on the revelation that wild pigs are now extinct on Guimaras, Cebu and Sequijor; all of islands which have been virtually deforested (Cox, 1975, 1987a; D. Kho, pers. comm.). A similar situation obtains on Masbate, though this island was not visited during the 1985 survey (see below), and on Bohol, where the last remaining population of wild pigs in the Rajaha Sikatuna National Park is said to be close to extinction (A. Alcala, pers. comm.; D. Kho, pers. comm.). However, it is not known whether the Bohol pigs are allied to S. cebifrons or S. philippensis, since this island is closest to Cebu but it forms part of the Mindanao Faunal Region. In either event, potentially viable populations of S. cebifrons are now confined to the western mountains of Panay, where their numbers are certainly declining, and to scattered fragments of surviving forest on Negros. This range is essentially identical to that of the critically threatened Philippine spotted deer (Cervus alfredi) and, in common with the latter species, all of the few surviving pig populations are subject to intense hunting pressure and the continued attrition and fragmentation of their remaining habitat.

Habitat, Ecology and Behavior

The natural vegetation of the Philippines consists mostly of lowland and montane rainforests, along the eastern side of the archipelago, which are replaced by monsoon forests on the western side. The latter include deciduous dipterocarp forests at elevations below 800 m and, in the central highlands of Luzon and Mindoro, extensive tracts of tropical pine forest. To varying extents, all of these formations have been reduced or degraded by agricultural developments, logging and mining, and large areas of cleared land have been replaced by tall grasslands, which are maintained by burning.

Wild pigs are reported to occur in all of these habitats, and may even benefit by the creation of secondary associations in disturbed areas and the proximity of cultivated foodstuffs. Catibog-Sinha (1978, 1981), who has undertaken the only ecological studies of these animals to date, argued that the wanton destruction of forests has compelled wild pigs to forage in neighbouring agricultural lots, though their depredations of crops are probably not confined solely to periods of food scarcity.

In the absence of any detailed studies on the behavioural biology of these species, the available information is sketchy and anecdotal. Pig hunters interviewed during the 1985 survey, reported that wild pigs (S. cebifrons) are usually found in groups of 4 or 5 individuals, but that groups of up to a dozen individuals were seen occasionally. Solitary males were also reported, but it was said that these were encountered only very rarely. These hunters also stated that the average number of piglets per litter was three or four, and that these were usually seen in the dry season (i.e. January to March in the western Visayas). Rabor (1986) has recorded that wild pigs (S. philippensis) on Luzon usually travel singly, in pairs or in groups of between seven and twelve individuals, and that these larger groups are generally composed of a boar, several sows and younger animals. The sows are reputed to give birth in well-protected sites, such as between the buttresses of giant dipterocarps, and that litter size is usually 5 to 8. However, it is not known whether these reports reflect real differences between the social behaviour and reproductive potential of the two species or a relatively higher adult and infant mortality rate in the Visayas. No discernable seasonal population movements amongst either species has been reported.

Threats to Survival

The principal threats to the fauna of the Philippines are the burgeoning human population (now numbering about 67 million people) and continued deforestation. At least 94% of the total land area of approximately 300,000 sq. km was originally covered by tropical forests. However, by 1988, satellite imagery had revealed that only about 21% natural forest cover remained. These problems are compounded by the depressed state of the economy, continued political unrest, and the generally low priority accorded to environmental protection issues. Worse still is the lack of any effective protected areas system in the country. In 1986, it was estimated that only 0.7% of the country's land area was designated for protection and a mere 0.3% more had been proposed (MacKinnon and MacKinnon, 1986). Current estimates are unlikely to have improved to any significant extent and, indeed, it has certainly worsened in some places. Many of the existing reserves exist only on paper, whilst others are either too small to be viable or are already deforested. At least two thirds of the national parks contain illegal settlements and/or have been partly logged, park boundaries are seldom properly demarcated, law enforcement is mostly lacking, staff are too few in numbers, poorly trained and remunerated, and hunting is rife.

As far the wild pigs are concerned these problems are not only exacerbated by intense hunting pressure throughout their ranges, but also by the generally negative attitudes of most local people towards these animals. Both species are most frequently encountered when they are hunted in the forest fragments or when they emerge from the shelter of those fragments to forage in neighbouring cultivation areas or 'kaingins'. In some areas farmers build bamboo fences to protect their crops or even go to the trouble of surrounding whole clearings with sharpened staves planted obliquely outwards to prevent the entry of wild pigs (Rabor, 1977). Nonetheless, the damage caused to agricultural smallholdings can be severe. As a result, no special conservation measures have been introduced to protect these animals which, far from being protected, are generally regarded as pests and, hence, a legitimate target for hunting activities. In the 1960's, the government officials distributed poison to farmers on Sibutu to destroy wild pigs (R. Hilado, pers. comm.), and even some officers from the (former) Bureau of Forest Development (BFD) have suggested that wild pigs should be hunted down and killed wherever possible (Cox, 1987a).

The close proximity of outlying human settlements to most of the remaining forest fragments also poses a potentially severe risk of disease transmission and/or genetic contamination to wild pig populations through increased likelihood of their contact with free-ranging domesticates. Experimental evidence for the fertility of hybrid S. scrofa x S. barbatus young has been cited by Mohr (1960), and hybrids from a domestic (ex-S. scrofa) sow and an S. philippensis boar (reputedly of Mindanaon origin) have been reared in a private collection in the Philippines. Several reports of wild hybrids being caught by local hunters on Negros have been received in recent years and a hybrid piglet (presumably a S. cebifrons x domestic cross) captured in the vicinity of Basay, S. E. Negros in 1992, is currently maintained at Silliman University, Dumaguete City. Clearly, any such hybridizations pose a serious threat to the genetic integrity of this population.

Conservation Action Taken

Much of the information on the current distribution, status and future management priorities for S. cebifrons are based on the 1985 field survey (Cox, 1985, 1987a), which resulted in its inclusion in the IUCN Red List of Threatened Animals (IUCN, 1986). One of the foremost recommendations arising from this survey was the creation of the proposed Panay Mountains National Park (40,000 ha), to protect the largest remaining population of spotted deer, but which probably also supports the single most important population of this species. A faunal survey and the drafting of a preliminary management plan for this Park have been undertaken (Cox, 1987b), and other activities relating to the development of the Philippine Spotted Deer Conservation Programme (Oliver et al., 1991) have facilitated the acquisition of additional data on the conservation status, systematic relationships and future priorities for research and management of these animals.

On Negros, wild pigs are known to occur on Mt. Silay and the Mangdalangan Mts. (collectively comprising the Northern Negros Forest Reserve, c. 45.000 ha) and Mt. Canlaon National Park (24,600 ha) in the north, and in scattered forest fragments in the south, including the environs of Mt. Talinis/Mt. Guinsayawan/Lake Balinsasayao (c. 30,000 ha), near Dumaguete City. However, in all of these areas wild pigs are subject to intense hunting pressure as well as the continued attrition of their remaining habitat through illegal logging activities. However, precise data on the extent of these threats is lacking owing to the remoteness of most of these areas and/or the presence of NPA rebels; both of which factors effectively negate their regulation or control.

S. philippensis is known or likely to occur in all of the larger national parks (Table 9) and possibly certain other designated protected areas within its range, though some of these areas exist on paper alone. Indeed, at least three national parks - Bulabog-Putian (854 ha) in Iloilo Province (Panay), and Sudlon (696 ha) and Central Cebu (11,893 ha) (both in Cebu) - which were formerly known to support remnant populations of S. cebifrons, have been virtually deforested (Catibog-Sinha, 1978; Cox, 1985).

Table 9. Existing and proposed national parks known or presumed to support wild pigs.

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Species/Area Size (ha) Location Comments

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S. cebifrons

Mt. Canlaon N. P. 24,557 Negros Mostly relatively intact montane rainforest, but now

isolated; wild pigs present but hunted.

Panay Mts N.P. c. 40,000 Panay Proposed to protect last area of remaining forest on

this island; probably supports single largest remaining pig population, but hunting is widespread.

Central Cebu N.P. 11,894 Cebu Virtually deforested, heavily encroached; wild pigs

extinct.

Sus sp./ssp. ?

Rajaha Sikatuna N.P. 9,000 Bohol Wild pigs reported to be close to extinction.

Mt. Iglit-Baco N.P. 75,445 Mindoro Formerly mostly montane rain forest, but now

largely disturbed or degraded; wild pigs common in some places.

S. philippensis

Mt. Data N.P. Luzon Mostly pine forest; no recent information on pigs.

Bataan N.P. 23,853 Luzon Monsoon forest; pigs (and hunting pressure)

reported.

Quezon N.P. 535 Luzon Remnant tract of lowland rain forest; pigs reported

in 1978, but no recent information.

Mt. Isarog N.P. 10,112 Luzon Wild pigs (and hunting pressure) reported in 1978;

no recent information.

Leyte Mts.N.P. c. 42,000 Leyte Mostly montane and semi-evergreen forest, though

some parts threatened by encroachment; probably still supports a good pig population.

Mt. Apo N.P. 72,184 Mindanao Formerly montane and lowland rain forest, but

most of latter lost to encroachment; wild pigs still present.

Mt. Malindang N.P. 50,000 Mindanao As Mt. Apo (above).

Captive Breeding

Small numbers of native wild pigs are maintained in several zoos and private collections in the Philippines. However, most of these animals are maintained as single individuals or small groups of animals of mixed origin, and no attempts have made as yet to start breeding programmes for any of the threatened, endemic forms in this country.

Additional Remarks

Recent data from ornithological surveys in Mt. Pulog in the Sierra Madre, indicate that the rooting activity of wild pigs may be of particular importance to certain ground feeding birds, such as the Koch's pitta (Pitta kochi), a poorly known threatened species endemic to Luzon. During these surveys, this pitta was observed only in the vicinity of such excavations, where it apparently forages on the invertebrates uncovered by the pigs (A. Jensen, pers. comm.).

Conservation Measures Proposed:

An Action Plan

Nowhere in the Philippines is environmental degradation quite so acute, and need for immediate conservation action quite so pressing, as in the West Visayas, or 'Negros Faunal Region'. This area is one of the most important centers of endemicity in the country but, even by Philippine standards, it has suffered a disproportionate extent of denudation, and the few remaining forests are chronically under-represented within the existing, and seriously inadequate, protected areas network. For all of these reasons, S. cebifrons emerges as one of a host of endangered endemics, and one the most threatened of all suids. The overwhelming priority for this species and, indeed, the terrestrial biota of this entire region, must be the early declaration, and effective future protection, of the (proposed) Panay Mountains National Park. The forests of western Panay are not only the sole surviving area of forest on this island, they are the single largest tract anywhere in the West Visayas and, hence, one of the most important tracts anywhere in the country. It is to be hoped, therefore, that this area and other important sites in the West Visayas (such as Mt. Canlaon National Park and the Northern Negros Forest Reserve in Negros Occidental and the area around Mt. Talinis/Mt. Guinsayawan/Lake Balinsasayao in Negros Oriental), will be upgraded within the context of the current review of priority sites for inclusion in the new Philippine 'Integrated Protected Areas System (IPAS)' which is being conducted by the Department Of Environment and Natural Resources (DENR).

In addition there is a need to address a number of outstanding questions about the distribution, biology and systematic relationships of these animals, and the generally negative attitudes of local people with respect to their future management needs. The principal objectives and priority projects for these species may be summarized as follows:

Objectives:

1. To promote and assist the enhanced future protection of the most threatened species/populations by increasing the number and size of existing reserves, and/or the effectiveness of protective measures, in those key areas where the protected areas network is inadequate to ensure the survival of the most threatened forms.

2. To promote further applied research on topics relevant to an improved understanding of the biology, systematics and future management requirements of the various Philippine endemic pigs, with a view to the enhanced protection of representative populations of all recognized taxa.

3. To design and implement such other practical conservation initiatives - including captive breeding, personnel training and public education programmes - as may be necessary to enhance the survival prospects of the most threatened taxa and a better understanding and appreciation of these animals at a local level.

4. To promote the development of conservation management policies directed towards the sustainable utilisation of wildlife resources in non-protected areas and/or where these are not in conflict with the overall survival prospects of threatened, endemic forms.

Priority Projects:

1. Promote and otherwise assist current proposals to develop effectively protected areas in the west Visayas, particularly the Panay Mountains National Park (west Panay), the Northern Negros Forest Reserve and Mt. Canlaon (north Negros) and the environs of Mt. Talinis and Lake Balinsasayao (south-east Negros).

All of these areas are known to support remnant populations of numerous critically threatened species endemic to the (West) Visayan faunal region, including the last known populations of S. cebifrons and C. alfredi.

2. Conduct field status surveys in selected locations and promote development of management plans for the enhanced future protection of other known, or possibly surviving, populations of S. cebifrons, in other critical sites in the West Visayas.

Data on the present status and/or the identity of the local wild pigs are required from:

· Masbate: this island was not visited during the 1985 survey, though it may still support remnant populations of S. cebifrons and other threatened Visayan endemics. The adjacent, smaller island of Ticao should also be investigated in this context.

· Bohol: small numbers of wild pigs are reported to survive on this island, which has been almost entirely deforested. However, it is not known whether these are S. cebifrons or S. philippensis, so taxonomic material (such as skulls or other hunting trophies) should also be obtained from this island.

· Sibuyan: wild pigs are known to survive on this island, but it is not known whether these are S. cebifrons or S. philippensis as no museum specimens have ever been obtained for study.

· Negros: additional and updated status data is required from several locations on this island where S. cebifrons has been reported to survive; including Mt. Silay, Mangdalangan Mts., Mt. Canloan, Mt. Talinis, Mt. Guinsayawan, Lake Balinsasayao and areas due east of Hinoba-an, which are of critical importance to the future survival prospects of this and other endemic taxa.

3. Develop a properly structured, cooperative breeding program for S. cebifrons, as a safeguard against its possible early extinction in the wild state.

In the first instance, at least, any such breeding program should be established at a recognized academic institution or conservation foundation on Negros or Panay, in order to facilitate the acquisition of the founder stock and promote local interest and research into the conservation and biology of these animals.

4. Promote and assist development of local conservation-education projects, including media coverage and the production and distribution of leaflets, posters and other materials.

The importance of the Philippines as a center of endemicity for wild pigs is almost entirely unknown to the relevant authorities, let alone the general public, and local attitudes to these animals are generally negative owing to occasional damage caused to crops planted in or close to forested areas. Recent experience has shown that teachers and members of the higher socio-economic groups (including landowners, local politicians, and the military and police forces, who include both decision-makers and many recreational hunters) are mostly unaware of the conservation significance of native wildlife species or the importance of protecting remaining forests, but are often receptive to suggestions appertaining to the patrimony of the country and the need to protect species unique to the region.

5. Conduct field status surveys in other, selected locations in the Philippines, which may support important populations of wild pigs and/or those whose taxonomic affinities have yet to be assessed.

These include Mindoro, Sibuyan, Bohol, Basilan and some other islands in the Sulu Archipelago. These surveys should be designed to determine the distribution, status, nature of threats and possible future management needs of any pigs that may occur there, and serve to obtain additional skin, cranial or other (soft) tissue specimens as may facilitate studies to determine the systematic relationships of these animals.

6. Encourage and support field studies on topics relevant to the future management of these species.

Very little field research has been conducted on any of the Philippines pigs, and such information as is available is therefore largely anecdotal. Comparative studies of their social and reproductive behaviour, ecology and habitat requirements, population dynamics, response to hunting pressure and commercial logging activities, etc., are all required.

7. Promote useful, comparative research on all captive wild pigs and the development of cooperative breeding projects between institutions/private individuals maintaining these animals.

At the present time there are small numbers of various other native wild pigs being maintained in city zoos, research institutions and private collections. Most of these animals are kept in non-breeding situations or in small mixed groups. Efforts should therefore be made to encourage the exchanges of specimens to promote breeding success and prevent inter-specific or inter-population hybridizations. These animals represent a potentially useful resource for research and training, and comparative studies of their behaviour and biology should be encouraged. Some priority should also be given to the collection of blood samples and other soft tissues for seriological and cytogenetic analyses. These could be collected relatively easily from captive animals, and could be expected to elucidate some outstanding questions about their genetic diversity and systematic relationships. For example, there are evident morphological differences between the wild pigs of the Luzon and Mindanao Faunal Regions, which need to be investigated in respect of the current (possibly unsatisfactory) assignment of both populations to the same monotypic taxon (S. philippensis). Similarly, the proposed separation of 'philippensis' and 'cebifrons' is almost entirely based on morphometric (osteological) and zoogeographic criteria, and the phylogenetic relationships between these taxa, and their distance from S. barbatus and S. celebensis, merit further investigation.

Acknowledgements

Most of the information on the distribution and status of the Visayan pigs was obtained during the course of field work funded by the Zoologischer Garten Berlin, Parc Zoologique et Botanique de la Ville de Mulhouse, Zoological Society of San Diego, Zoological Society of London and the Fauna and Flora Preservation Society. We are particularly grateful for the assistance provided by the Protected Areas and Wildlife Bureau and the Ecosystems Research and Development Bureau, of the Department of the Environment and Natural Resources, Govt. of the Philippines; the Department of Biology and the Centre for Tropical Studies, Silliman University; the Natural History Museum, London; and the World Conservation Monitoring Centre, Cambridge. Invaluable information or other assistance was provided to us by Louella Dolar, Ely Alcala, Ramon Hilado, Emmanuel Tangco, Carlo Custodio, Marlynn Mendoza, Simplicia Pasicolan, Roland Wirth, Peter Grubb and Juliet Clutton-Brock. Peter Cuypers and Paul Vercammen prepared the distribution map, and Raleigh Blouch, Peter Grubb and Alastair Macdonald all provided useful comments on earlier drafts of this text.

References

Catibog-Sinha, C. S. 1978. Wild pigs (Sus celebensis ssp.) in the Philippines (Part 2). In: Wild Plants as Potential Feeds for Wild Pigs; Ready References, Monograph No. 5; Forest Research Institute, College, Laguna, Philippines: 17-29.

Catibog-Sinha, C. S. 1981. The quantity and quality of wild food plants and the depredations of wild pigs in the Philippines. (Unpubl.) Ph.D. thesis, Oklahoma State University, Stillwater, Oklahoma: 237 pp.

Cox, C. R. 1985. A field survey of the distribution and conservation status of the wild pig (Sus barbatus cebifrons) and Prince Alfred's spotted rusa (Cervus alfredi) in the Visayan Islands, Republic of the Philippines. (Unpubl.) rep. to the IUCN/SSC Pigs and Peccaries Specialist Group: 27 pp.

Cox, C. R. 1987a. The Philippines spotted deer and the Visayan warty pig. Oryx 21 (1): 37-42.

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