The Wombat is a Australian marsupial, in appearance rather like a small, very short-legged and muscular bear. Wombats feed on grasses, sedges and roots, and dig extensive burrow systems with their rodent-like front teeth and powerful claws. Although mainly crepuscular and nocturnal, wombats will also venture out to feed on cool or overcast days. They are not as easily seen as many animals, but leave ample evidence of their passage, treating fences as a minor inconvenience to be gone through or under.
Wombats, like all the larger living marsupials, are part of the Diprotodontia, which has two sub-orders: the large and diverse Phalangerida (kangaroos, possums, and relatives), and the Vombatiformes (which is the Latin for "wombat-shaped things"). Five of the seven known families are extinct, only the koala and the three species of wombat survive. The ancestors of the wombat evolved sometime between 55 and 26 million years ago (no useful fossil record has yet been found for this period) and about 12 species flourished until well into the ice ages. The Diprotodon, or giant wombat, was the largest marsupial to ever live and coexisted with the earliest inhabiants of Australia.
Wombats have an extraordinarily slow metabolism, taking around 14 days to complete digestion, and do not move quickly often. When required, however, they can easily out-run a human, and summon immense reserves of strength - the primary defence of a wombat against a predator underground (such as a dog) is to crush it against the roof of the tunnel until it stops breathing.
There are three species, all around a metre long and weighing between 20 and 35kg.
- The Common Wombat (Vombatus ursinus) is widespread in the cooler and better watered parts of southern and eastern Australia, and in mountain districts as far north as the south of Queensland, but is declining in Western Victoria and South Australia. Common wombats can breed every two years and produce a single cub, which leaves the pouch after six to nine months but follows the mother about and breast-feeds for another year.
- The Southern Hairy-nosed Wombat (Lasiorhinus latifrons) is found in scattered areas of semi-arid scrub and mallee from the eastern Nullarbor Plain to the New South Wales border area. It is the smallest wombat at around 775 to 935mm and 20 to 32kg, and the young often do not survive dry seasons. It is classified as vulnerable: a healthy population still remains but appears to be ageing: it is feared that the consistently sparse rainfall of recent years has prevented successful breeding. (It takes three consecutive good seasons for a Southern Hairy-nose to reach near-adulthood.) Wombat specialists are concerned that a continuation of the current trend to dryer climate in arid Southern Australia could be a serious threat to the Southern Hairy-nose wombat.
- The Yaminon or Northern Hairy-nosed Wombat (Lasiorhinus krefftii), was found across New South Wales, Victoria and Queensland as recently as 100 years ago, but is now restricted to a tiny 300ha range within the 3160ha Epping Forest National Park in Queensland. It is probably the rarest large mammal in the world and is critically endangered, with 70 to 100 individuals remaining. Slightly larger than the Common Wombat and able to breed a little faster (two young every three years), it has very little habitat left and the remaining 300ha has become infested with African buffel grass, which out-competes the native grasses Yaminon prefers to feed on. A two metre-high predator-proof fence was constructed around 2500ha of the park in 2000, but captive breeding and translocation programs have been abandoned for the time being because the population in the sole remaining Yaminon colony is considered too small to allow the safe removal of the 15 or 20 individuals needed to start a new wild colony, and because more than a decade of captive breeding research with Common and Southern Hairy-nosed wombats has produced only a handful of successful births.