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Home , Babirusa, Babyrousa bolabatuensis, Bubalus, Buru babirusa, Giant forest hog, North Sulawesi babirusa

The Project

By David Twamley

The (or ‘-’) are a of bizarre-looking from islands in , , which is home to a mixture of of Asian and Australasian origin.

Contents:

1. 2. Physical appearance 3. Distribution and habitat 4. Feeding and society 5. Reproduction 6. Threats and conservation 7. Fun facts 8. Genera of 9. Other wildlife of 10. My experiences with babirusas

Taxonomy

Babirusas are members of the pig family, Suidae. There are three known different of Babirusa, which until 2002, were considered of a single species, Babyrousa babyrussa. Now all those subspecies have been re-classified as distinct species based on morphological studies. The species are as follows:

 Babyrousa babyrussa - the hairy or golden babirusa, from the Sula islands and in the Moluccas.  Babyrousa togeanensis - the Togian babirusa, the largest species, from the Togian islands off the coast of Sulawesi.

Figure 1: this is a Togian babirusa, taken from http://scienceblogs.com/tetrapodzoology/2010/02/23/many-babirusa-species/

 Babyrousa celebensis - the , the best known species, the one often seen in zoos.  – a proposed fourth species, the Bola Batu babirusa, from the south-east of Sulawesi. This species is only known from bones that are not fully fossilized. It has never been seen alive.

Many other animals that were once considered single species have also been split into at least two different species, usually based on DNA tests. Examples include African elephants, gorillas, orang-utans, sifakas and other lemurs, , kiwis, ostriches, pipistrelle bats, and giraffes, among others. Physical appearance

There are some differences between the species of babirusa. However, all have a pair of strange, curling tusks that pierce through the pig’s snout and curl towards its forehead, giving the babirusa a prehistoric appearance. The tusks may eventually pierce the ’s skull, so in zoos, some have had their tusks partially removed. These tusks are only present in the male. Like other pig species, the male also has large tusks in his lower jaw. Females have no or smaller tusks. The tusks are different for each species: in the , the tusks are short and slender, laterally crossing the lower tusks (Figure 2); in the Togian species, the tusks are also slender and short, but also rotate forwards and always converge; and in the Sulawesi babirusa, the canines are long and relatively thick, emerging vertically, converging slightly and curling dorsally, so the tusks make a circle. The tusks are also what give the animals’ their name; “Babirusa” which is Indonesian for “Pig-deer”, because it reminds some people of the of a stag.

Figure 2: skull of a hairy babirusa, taken from https://commons.wikimedia.org/wiki/File:Babyrousa_babyrussa_02_MWNH_123a.jpg

Like other pigs, babirusas are even-toed (the of which also includes , and ). They have four toes on each foot, but walk on the enlarged middle two. While the Sulawesi babirusa is virtually hairless, the other two known species have more body hair. The hairy babirusa has a fur coat that varies in colour from white to gold, with a black rump. The togian species has shorter hair, with darker upperparts that also vary in colour.

Distribution and habitat

The babirusas are endemic to Indonesia, specifically Wallacea, which includes the island of Sulawesi (formerly known as Celebes), the Lesser Sunda Islands, the Maluku islands and Timor. Named after the explorer, Alfred Russel Wallace (1823-1913), the region is home to distinctive animals of Asian and Australasian origin. The islands of Wallacea have been isolated since about the end of the (200 million years ago), which has resulted in many endemic species that are seen today, such as the Komodo dragon (Varanus komodoensis), which occurs in the Lesser Sunda Islands.

Figure 3: where in Indonesia the babirusas can be found, taken from http://scienceblogs.com/tetrapodzoology/2010/02/23/many-babirusa-species/

It’s believed that the babirusas from Sula and Buru were introduced by people as royal gifts, but since these animals are excellent swimmers, it is possible that they made it to the islands themselves. They prefer tropical forests along the banks of rivers.

Feeding and Society

Like other pigs, babirusas are omnivorous, eating whatever they can find, and what’s edible to them. They feed on fruits, leaves, and roots, but, of course, being omnivorous they also eat small mammals and other animals they can catch. Disturbingly, adults have also been known to cannibalize young babirusas as well. Their digestive tract is similar to that of a (Sus scrofa domesticus), and the diverticulum in the stomach is enlarged, indicating that the babirusa is a . They have strong teeth and jaws which reportedly allow them to crack hard nuts easily. With its upper canines cutting through its nasal cavities, the babirusa does not use its nose to dig for food, except in mud. Rather, they use their front hooves for digging.

Volcanoes are common in Sulawesi, and deposits of salt can be found near hot springs. Babirusas occasionally visit these salt licks, and indulge in social activities such as courtship and combat, as well as chewing on the rocks, ingesting soil, and drinking out of the spring. It’s possible that the pigs do this to obtain enough sodium.

The boars are solitary animals, rarely travelling in pairs or trios, whereas sows and their piglets form herds of up to 84. Active during the day, the babirusa reportedly constructs nests in which to sleep, by breaking off branches with its jaws. However, it is also said that they simply sleep in depressions made in the ground.

During fights, a male babirusa doesn’t use his upper canines as weapons, as they are considered brittle. Instead, they are used for defence, and the lower tusks are offensive weapons. When fighting, the males jump up on their hind legs and hit out at their opponent with the forelegs.

Figures 4 & 5: a tusked male (left) and a tusk-less female (right), taken from http://www.arkive.org/sulawesi-babirusa/babyrousa- celebensis/

Reproduction

Figure 6: a male and female Sulawesi babirusa, taken from ARKive

The mating season for babirusas takes place from January-August. Female babirusas are in heat for 2-3 days. A female constructs a nest from branches that she breaks off of bushes and trees. The nest may be 25 cm deep and 3 metres in length. After a gestation of between 155-158 days, typically one or two piglets are born. This is unusual compared to other pigs, which often produce large litters. This is because the female babirusa has only two teats (one pair). In captivity, babirusas have been known to at all times of the year. A babirusa may become sexually mature at 5-10 months old, and live to an age of 24 years.

Babirusas have been known to interbreed with domestic pigs. For instance, in 2006, a male Sulawesi babirusa was accidentally allowed to breed with a female domestic pig at the in Denmark. This resulted in a litter of 5 piglets, which had teeth resembling those of their babirusa father.

Figure 7: Female babirusa and , taken from ARKive Threats and Conservation

According to the International Union for the Conservation of Nature (IUCN), the Sulawesi and Buru species of Babirusa are vulnerable to , while the Togian babirusa is classified as endangered. Despite being protected under Indonesian law, the three species are threatened by hunting and . Loss of forest cover makes the babirusa more exposed to hunters, and they are the first animals to vanish when the rainforest they inhabit is destroyed for logging. There may be fewer than 10,000 Sulawesi babirusas left in the wild, while the Togian babirusa is among the most threatened members of the Suidae, along with the (Porcula salvania) and the (Sus cebifrons).

As already mentioned, all species of babirusas are protected in Indonesia, which makes it illegal to kill these pigs. They are also present in many protected areas, but these measures are not efficient enough to prevent the extinction of these remarkable mammals. The Sulawesi babirusa can be found in many zoos around the world, and the in New York has a good breeding record for this species. Unfortunately, captive numbers of the babirusa in Europe are highly inbred, which means that closely related individuals have bred and produced infertile offspring. A Solution would be to import Babirusas from zoos in America or South-east Asia, bringing new blood to the European population. The European Programme (EEP) for the babirusa is held at Opel zoo in Germany.

Figure 8: Bukaan, born in 2016, with mother Kendari, at , taken from http://www.chesterzoo.org/whats-happening/zoo- news/2016/11/rare-babirusa-on-film Fun facts

 Experts believe that the babirusas are among the most basal members of the pig family, branching off from the branch millions of years ago around the epoch.  The babirusa has been observed reaching for high leaves on its hind legs, in a similar manner to the (Litocranius walleri) of .  The Sulawesi babirusa is the only babirusa species kept in zoos, although some people believe that the Buru babirusa also occurs in captivity, and that no captive Sulawesi babirusas exist outside America.  In captivity, babirusas have been observed ploughing into soft sand, forming a deep furrow by kneeling down and pushing their head forward through the sand. While ploughing, the hogs growl and snort, and produce strange, foamy saliva. Males plough most vigorously if they share their enclosure with another male. Although the exact function of this ploughing is not certain, one theory is that it’s used for scent- marking.  It seems that humans have known the babirusa since prehistory. Cave paintings found in Sulawesi have been dated to 35,000 years old (making them one of the oldest known pieces of art), and include hand stencils and figures of wild animals, including babirusas.  It’s sometimes said on the internet, that the babirusa is more closely related to hippos than to other pigs, but most scientists agree, based on various lines of evidence, that hippos are more closely related to and dolphins than to pigs, as previously thought, so the babirusas remain in the Suidae family. But even though they aren’t related, the babirusas do look a bit like hippos in appearance.

Figure 9: Male Sulawesi babirusas in ‘bipedal boxing’, taken from ARKive Genera of Suidae

The following images feature representatives of the 6 extant genera of the Suidae family, which includes Babyrousa.

Clockwise from top to bottom: Sus (, warty pigs and bearded pigs), Porcula (pygmy hog, formerly included in Sus), ( and bush pig), Babyrousa (babirusas), Phacochoerus (warthogs) and Hylochoerus (). All photos were taken from ARKive.

Note: although the of the Tayassuidae are closely related to pigs, they are no longer classified as members of the Suidae.

Other wildlife of Sulawesi

Babyrousa celebensis may be one of the most well-known endemic species of Sulawesi, which is one of the four Greater Sunda Islands in Indonesia, and the 11th largest island on Earth. However, there are many other animals only found on this island. Here are a few:

Clockwise from top to bottom: Lowland ( deppressicornis), the smallest of the world’s wild but the largest of Sulawesi’s land animals, one of two species of anoa, the other being the mountain anoa (Bubalus quarlesi), also native to Sulawesi; Crested black macaque (Macaca nigra), the most endangered of several species of macaque native to Sulawesi; Bear cuscus (Ailurops ursinus), one of two species of cuscus found on the island, and one of the few marsupial species native to Asia; Maleo (Macrocephalon maleo), a large megapode gamebird that buries its eggs in volcanic sands, the best known of Sulawesi’s endemic bird species. All of these species are threatened with extinction. All photos were taken from ARKive.

62% of the land mammals found in Sulawesi are endemic, but the number of endemic birds is only half that percentage. Some species of freshwater fish are also found only in Sulawesi. The Wallacea region itself has a large number of endemic species, as a result of millions of years of isolation. There are 82 of land-living vertebrates, six of which are critically endangered. Threatened endemic species in Wallacea include the Vulnerable Komodo dragon and the Salmon-crested cockatoo (Cacatua moluccensis). There are also 1,500 species of plants endemic to Wallacea.

My experience with babirusas

The first time I heard of the babirusa was from a Dorling Kindersley handbook on mammals that I got around 2007. The book was published in 2002, the same year that they were split into multiple species. At that time, I liked the sound of the name ‘babirusa’, though I wasn’t a fan back then. In 2012, I got a book on the illustrated history of Dublin zoo, with one page showing a plan for the zoo in the future that mentioned ‘babirusa’ in the Asian rainforest section. On one visit to the zoo, a staff member told me that the zoo may be getting babirusas sometime in the future, although the zoo has no plans at present. Probably the first time I saw a babirusa was at the Chester zoo in August 2014, but we didn’t take very decent photographs. The only two photos we have of the babirusa (one of which is shown below) show it from a distance, hiding its face in some vegetation. Two years later, in September 2016, my family and I watched a documentary on BBC called ‘Ingenious animals’. One episode featured ‘Albus’, a male babirusa at in Kentucky who was limping, which limited his success at fathering offspring, until he received acupuncture. The programme was what got me into babirusas. I also saw babirusas on David Attenborough’s series ‘’. A year on and I am still into these pigs. I wrote a letter to Leo Oosterweghal, director of Dublin zoo, and mentioned about the babirusas, making suggestions as to what their enclosure should look like. By then, I had already thought of the possible reason why the zoo would like these special pigs: the macaques. Both the babirusa and crested black macaque are native to Sulawesi, and Dublin zoo actively supports the Selamatkan Yaki project for the macaque in Sulawesi. Though, as I have mentioned, they have no plans to receive them yet.

Figure 10: one of the photos we took of the babirusa (in the centre) at Chester zoo. Thank you for reading

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