The Babirusa Project
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The Babirusa Project By David Twamley The Babirusas (or ‘pig-deer’) are a genus of bizarre-looking pigs from islands in Wallacea, Indonesia, which is home to a mixture of animals of Asian and Australasian origin. Contents: 1. Taxonomy 2. Physical appearance 3. Distribution and habitat 4. Feeding and society 5. Reproduction 6. Threats and conservation 7. Fun facts 8. Genera of Suidae 9. Other wildlife of Sulawesi 10. My experiences with babirusas Taxonomy Babirusas are members of the pig family, Suidae. There are three known different species of Babirusa, which until 2002, were considered subspecies 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 Buru 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 North Sulawesi babirusa, the best known species, the one often seen in zoos. Babyrousa bolabatuensis – 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, warthogs, kiwis, ostriches, pipistrelle bats, elk 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 animal’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 Buru babirusa, 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 antlers 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 ungulates (the order of mammals which also includes alpacas, moose and saiga antelope). 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 Triassic (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 domestic pig (Sus scrofa domesticus), and the diverticulum in the stomach is enlarged, indicating that the babirusa is a ruminant. 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 breed 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 Copenhagen zoo in Denmark. This resulted in a litter of 5 hybrid piglets, which had teeth resembling those of their babirusa father. Figure 7: Female babirusa and piglet, 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 extinction, while the Togian babirusa is classified as endangered. Despite being protected under Indonesian law, the three species are threatened by hunting and habitat destruction. 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 pygmy hog (Porcula salvania) and the Visayan warty pig (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 Bronx zoo 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 Endangered species Programme (EEP) for the babirusa is held at Opel zoo in Germany. Figure 8: Bukaan, born in 2016, with mother Kendari, at Chester zoo, 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 warthog branch millions of years ago around the Miocene epoch. The babirusa has been observed reaching for high leaves on its hind legs, in a similar manner to the gerenuk (Litocranius walleri) of Africa. 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.