Groves (2001) and Meijaard and Groves (2002a, b) proposed to upgrade the three extant subspecies of Babyrousa to species level: B. celebensis from northern Sulawesi; B. togeanensis from the Togian islands; and B. babyrussa from Buru and the Sula Islands. A single skull from central Sulawesi may or may not represent the species known otherwise only as a subfossil from the southern peninsula, B. bolabatuensis. The taxonomic identity of the individuals from central, eastern and southeastern Sulawesi was left undecided. For this reason we treat all individuals occurring on Sulawesi, Muna, Buton and Lembeh as belonging to one taxonomic unit, as was the case in the old taxonomy. All animals from Sulawesi, Muna, Buton and Lembeh are therefore treated as Babyrousa celebensis, pending resolution of the taxonomy. A large taxonomic study based on skull and tooth morphology as well as molecular genetic analyses is close to completion.

Listed as Vulnerable because of a population decline, estimated to be more than 30% over the last three generations (approximately 18 years), inferred from over-exploitation, shrinkage in distribution, and habitat destruction and degradation; and because the population size is estimated to number fewer than 10,000 mature individuals, there is a decline of >10% expected over the next three generations. It was once thought to be reasonably common, but the species has disappeared from the eastern tip of the northern peninsula and is under severe hunting pressure in at least northern, central and southeast Sulawesi. Elsewhere on the island there has been, and is ongoing, habitat loss, fragmentation and degradation. The Red Listing of the Sulawesi Babirusa is dependent on its taxonomy. Should the ongoing genetic and anatomical studies later indicate that central and/or eastern, and/or southeastern Babirusa are different from those of the northern peninsula, the Red List status of especially the northern peninsula population will become more severe.

Babyrousa celebensis is endemic to Indonesia, and, as defined here, occurs widely on Sulawesi, with the exception of the southwestern peninsula where the form bolabatuensis is known from subfossials (Hooijer 1950). It is also known from offshore islands, including Muna, Buton and Lembeh. On the northern peninsula of Sulawesi, they have disappeared from the most northereastern section and their distribution may now be largely limited to the western end of the Bogani Nani-Wartabone National Park, the Nantu Wildlife Reserve, the Panua Nature Reserve, the western area of the remaining forests in Randangan (Pahuwato Regency of Gorontalo Province) and in the Buol Toli-Toli region; all in the western half of the peninsula (Riley 2002, DKKH 2015). The Babirusa still occurs in central Sulawesi and the eastern and southeastern peninsula, although precise information regarding the current extent of occurrence and area of occupancy is lacking (Macdonald 1993, Alvard 2000, Burton 2002, Riley 2002, Wiles et al. 2002). The species is unlikely to still occur on the severely deforested southern island of Muna. On Buton the species was not found during recent mammal surveys (Meijaard and Groves 2002b, Wiles et al. 2002) and no Babirusa skulls were found during a recent visit to the island in search of anoa skulls (J. Burton pers. comm.). Its continued presence on the island of Lembeh is also uncertain.

B. celebensis has been largely extirpated from the northeast tip of the northern peninsula, and is being brought to markets in the neighbourhood of Manado from practically all over Sulawesi at an alarming rate (Milner-Gulland and Clayton 2002, Lee et al. 2005). Recent survey data strongly suggest that populations in the wild are seriously depleted (Riley 2002). Babirusa appear to have become rare in Lore Lindu National Park, but may be more common in the area to the north of Palu (Riley 2002, Burton 2002).

The Sulawesi Babirusa inhabits tropical rain forest on the banks of rivers and ponds abounding in water plants. Whereas in the past the animal has tended to occur in low lying areas near coasts, recent anecdotal and survey reports indicate that it is now confined mostly to the interior, on higher and less accessible ground (Riley 2002).

In common with most of the other suids, Babirusa are omnivorous and both wild and captive individuals consume a wide variety of leaf, root, fruit and animal matter (invertebrates and small vertebrates). They visit volcanic salt licks and drink the water and ingest the soil (Clayton 1996, Leus et al. 2002). Although detailed studies of their diet in the wild still need to be carried out, a review of the available information from the wild combined with studies on the stomachs and digestive abilities of captive animals suggest that from an anatomical/digestive point of view, they are most likely non-ruminant forestomach fermenting frugivores/concentrate selectors (Leus et al. 2004). Their jaws and teeth are reported to be strong enough to crack very hard nuts with ease. However, Babirusa do not exhibit the rooting behaviour typical of other suids because of the absence of a prominent rostral bone in the nose (Macdonald 2016). They will probe soft sand as well as wet, muddy places for food.

In northern Sulawesi groups or troops of up to 13 individuals have been observed in rainforest, especially around water, communal wallowing areas and salt licks (Patry et al. 1995, Clayton 1996). Older adult males were often observed singly and most groups were composed of five or fewer animals, the majority of which were females with young animals.

Babirusa are hunted for food to supply the Christian markets in North Sulawesi (Blouch 1990, Burton 2002, Milner-Gulland and Clayton 2002, Lee et al. 2005). As the species becomes rare or absent from eastern sections of the northern peninsula, hunting is moving to the west and centre. For example, Babirusa from the area to the north of Palu and from Lore Lindu National Park (although the species now appears severely depleted in the latter) are being hunted and sold to traders from North Sulawesi (Burton 2002).

The species is also increasingly threatened by commercial logging, and by the spread of other land-uses resulting in forest conversion and degradation (MacDonald 1993, Riley 2002). Total lowland forest loss on the island is estimated to be likely more than 75% (Riley 2002). An additional threat is present in the form of prospective iron ore mining, particularly in the northwestern part of the northern peninsula. The natural dry zone in the northwest of central Sulawesi is probably prone to further drying as a result of climate change. Details are sparse, but reduction in tree cover and fruiting would result.   In southeast Sulawesi there has been an expansion of cultivated areas for commercial tree-fruit crops. Babirusa in the forest are being caught in traps set for anoa; they are killed and left to rot in the forest as the local muslim hunters view them as vermin contaminating their traps (Macdonald 2016). In the more coastal areas, some Babirusas are being deliberately trapped to supply teeth to the Bali mask-making trade (Macdonald 2016). Villages of Balinese people around the coast are also stimulating the ‘pig-meat’ trade. Throughout the island human population expansion continues, with towns expanding and restaurants increasing in number and servicing a wider range of non-muslim tastes.

Babirusa are hunted for food to supply the Christian markets in North Sulawesi (Blouch 1990, Burton 2002, Milner-Gulland and Clayton 2002, Lee et al. 2005). As the species becomes rare or absent from eastern sections of the northern peninsula, hunting is moving to the west and centre. For example, babirusa from the area to the north of Palu and from Lore Lindu National Park (although the species now appears severely depleted in the latter) are being hunted and sold to traders from North Sulawesi (Burton 2002).

The species is also increasingly threatened by commercial logging, and by the spread of other land-uses resulting in forest conversion and degradation (MacDonald 1993, Riley 2002). Total lowland forest loss on the island is estimated to be likely more than 75% (Riley 2002).  An additional threat is present in the form of prospective iron ore mining, particularly in the northwestern part of the northern peninsula.  The natural dry zone in the northwest of central Sulawesi is probably prone to further drying as a result of climate change. Details are sparse, but reduction in tree cover and fruiting would result.  In southeast Sulawesi there has been an expansion of cultivated areas for commercial tree-fruit crops. Babirusa in the forest are being caught in traps set for anoa; they are killed and left to rot in the forest as the local muslim hunters view them as vermin contaminating their traps (Macdonald 2016). In the more coastal areas, some babirusa are being deliberately trapped to supply teeth to the Bali mask-making trade (Macdonald 2016). Villages of Balinese people around the coast are also stimulating the ‘pig-meat’ trade.

Throughout the island human population expansion continues, with towns expanding and restaurants increasing in number and servicing a wider range of non-muslim tastes.

The babirusa was accorded full protection under Indonesian law since 1931 (Dammerman 1950, Setyodirwiryo 1959). It is currently protected by Indonesian law Act No. 5/1990 Conservation of Living Resources and Their Ecosystems, Undang-un dang Republik Indonesia Nomor 5 Tahun 1990 Tentang Konservasi Sumber Daya Alam Hayati Dan Ekosistemnya). In 2013, the Indonesian government released a taxon-specific conservation strategy and action plan (Strategi Dan Rencana Aksi Konservasi Babirusa Tahun 2013-2022) (DKKH 2015). The national action plan identifies 11 priority conservation sites for babirusa on Sulawesi (Bogani Nani Wartabone Connected Area, Sojol-Nantu Mountain Connnected area, West and East Coast of the narrow portion connecting North and Central Sulawesi, Lore Lindu Connected Area, Morowali, Bakiriang Connected Area, Lombuyan, Latimojong Mountains, Takolekaju Mountains, Verbek Mountains, and the Tangkeleboke-Abuki-Mataromba Mountain Connected Area (DKKH 2015).

The species has been included on Appendix I of  CITES  since 1982, although international trade in this species is not thought to be have been an important issue in recent times (Macdonald 1993). 

The species occurs in several protected areas of various levels on Sulawesi (e.g. western area of the Bogani Nani Wartabone National Park, the Nantu  Wildlife Reserve , Lore Lindu National Park,  Rawa  Aopa  Watumohai National Park, the Panua Nature Reserve, Morowali Nature Reserve and others (Macdonald 1993, Alvard 2000, Riley 2002, Wiles et al. 2002, DKKH 2015, http://www.bbc.co.uk/nature/animals/features/274feature3.shtml - accessed 5 June 2008). The species often remains under hunting pressure even in protected areas.

There is an international studbook for the world captive population of babirusa maintained by Opel Zoo (Germany). The world captive population counts 190 individuals in 34 institutions (Kauffels pers. com.). In 2014 an MOU was signed by representatives of the Indonesian Zoo Association (PKBSI), the European Association of Zoos and Aquariums (EAZA), the Association of Zoos and Aquariums (AZA), the International Union for the Conservation of Nature Species Survival Commission (IUCN SSC), the IUCN SSC Asian Wild Cattle Specialist Group, and the IUCN SSC Wild Pig Specialist Group (witnessed by the Indonesian Ministry of Environment and Forestry) agreeing to apply for the development of a Global Species Management Plan (GSMP) for Babyrousa sp. (administered by the Wold Association of Zoos and Aquariums (AAZA)) and jointly planning how the ex situ population and community can best contribute to the conservation of this taxon within the framework of the Indonesian National Action Plan. The GSMP planning meeting took place in January 2016.