A mystery liver disease thought to be caused by introduced weeds is causing hairy-nosed wombats in southern Australia to go bald and die, researchers said Tuesday. The illness, which causes the wombat to lose some or all of its fur and then starve to death, is tearing through South Australia\'s native southern hairy-nosed wombats, threatening entire populations. Peter Clements from the state\'s Natural History Society said wildlife rescue workers had discovered \"several hundred\" sickened animals in the Murraylands region near Adelaide, where up to 85 percent of the population was unwell. \"They tend to lose their fur in patches and sometimes in whole,\" Clements told AFP. \"You can see the bones showing through and they\'re generally immobile, they just sit there in the sun all day and try to keep warm.\" Clements said it was unusual to see the wombat, a nocturnal creature, out during the day and when they were in daylight \"we know that they\'re in trouble.\" Initially the animals were thought to have mange, but it became so widespread and severe -- with shiny, healthy skin revealed beneath -- that autopsies were carried out to determine what was causing the illness. University of Adelaide researcher Wayne Boardman said the non-native toxic potato weed appeared to be affecting the wombats\' livers, triggering a reaction with ultraviolet light that caused them to lose their fur. Boardman said it was unclear why the herbivorous wombat had suddenly taken to eating the noxious weed but a shortage of their usual grasses and alternative foods due to prolonged local drought could be to blame. \"We have a feeling it might well be a struggle to find enough vegetation, leading them to eat other plants like weeds, and particularly potato weed, which is then having a deleterious effect on the liver,\" Boardman told ABC Radio. The creatures were also roaming in areas where they were not usually seen, supporting the theory that there were food shortages and they \"have to move out to find vegetation\", he added. Squat and thickly furred, wombats are small burrow-dwelling marsupials that walk on all fours and are bear-like in appearance with a wide muzzle and a flattened head. They are not a threatened species but Boardman said the population in parts of South Australia state could die out completely if their habitat was not restored to a healthy balance of native plants. Brigitte Stevens, from the Wombat Awareness Organisation, said it was a \"huge and overwhelming\" problem. \"Some of them are just lying down... on their side and just eating dirt. You know, they can\'t even lift their heads,\" she told ABC.