While Australia's northern hairy-nosed wombat may be one of the world's most endangered mammals, its southern cousin has, by comparison, thrived. But now a food shortage and an invasion of toxic plants has killed thousands of southern wombats, prompting fears of a local extinction.
The southern hairy-nosed wombat is in a parlous state in the Murrayland region of South Australia, one of its main population areas. Many animals are emaciated, and have also lost their coats, making them susceptible to skin diseases and sunburn.
Brigitte Stevens, who runs the Wombat Awareness Organisation, has been making food drops in the area. "We're up there four or five times a week, and we see hundreds of dead wombats every time. There's just nothing for them to eat. They're literally starving to death."
Stevens takes sick and malnourished wombats to a care centre in the Adelaide Hills. There the animals sleep in cots, beneath feather duvets, and are fed pureed sweet potato from a bottle.
The principal cause, according to animal welfare groups and veterinary scientists, is that the native grasses which are the wombats' staple food have been pushed out by exotic plants such as onion and potato weed. The situation, created by poor land management, has been exacerbated by two years of above average rainfall during which the weeds have flourished. Not only do the weeds provide scant nutrition, but many of them are toxic and can cause liver disease.
One of three species of wombat, the southern variety is found in the grassy plains and open woodland of southern Australia. The wombats live mainly underground and usually put on most of their fat supplies in winter and spring, when food is more plentiful, enabling them to survive the summer.
They live principally, though, on farming properties that have been over-grazed by sheep and cattle in the past and recently de-stocked. "That has led to an imbalance in the eco-system, with the loss of native plants and overgrowth of weeds," Dr Lucy Woolford, a veterinary pathologist at Adelaide University, said.
The southern hairy-nosed wombat is still well off compared with the northern species, which crashed to a low of just 35 individuals in the 1980s. Intensive conservation efforts including IVF techniques to boost their fertility and building a predator-proof fence around their sole remaining colony, in central Queensland, have boosted their numbers to 138.
No one is sure how many southern wombats are left. No survey has been conducted since 1989.