Koalas across Queensland are dying from the spread of an AIDS-like virus which weakens their immune system, and could become extinct within 15 years, a leading researcher says.
''We're seeing a 100 per cent infection rate in the populations we're studying. On those figures, it should be considered a disease epidemic,'' Australian Wildlife Hospital research director Jon Hanger said.
The disease, known as koala retrovirus, was genetically sequenced by Dr Hanger in 1999 and has been linked to 80 per cent of deaths in captive koalas in Queensland from leukaemia, lymphoma, malignant tumours and immune deficiency disorders.
The spread of the virus, combined with loss of habitat caused by urban development, has already made ''localised extinctions of koalas commonplace in some areas of Queensland'', Dr Hanger said.
''We are losing the battle, and koala populations in smaller fragmented habitats are doomed to extinction.
''We have hammered our biodiversity like you wouldn't believe. If you look at a map of Australia on Google Earth you'll see how few fragments of native vegetation are left across the continent. We have gone way beyond the tipping point for many of our ecosystems.''
State and federal governments failed to understand the severity and impact of the fatal retrovirus and were relying on ''antiquated legislation'' to conserve Australia's koalas, he said.
Current laws protecting Queensland's koalas did not address new demands to conserve the species, such as hand-rearing of orphaned joeys, translocation to new habitat, rehabilitation of injured wildlife or the need to protect food trees and habitat.
''They were written at a time when the main aim was to make it illegal to kill or collect koalas. They need to be urgently revised to factor in threats posed by climate change, the rapid spread of disease and urban development.''
The Australian Wildlife Hospital and University of Queensland issued yesterday a progress report on a study tracking movements of hand-reared young koalas released on to a rural conservation property on the Darling Downs.
Dr Hanger said the greatest distance travelled was 14km from the release site and reproductive success was high among the group. But the koalas also had to contend with the risks of feral dog attacks, ''misadventure associated with interaction with cattle'', clearing of trees by local property owners, and worsening drought conditions.
Dr Hanger's predictions regarding local extinctions of koalas follows new research published earlier this week in the international science journal Nature. It warns the risk of species extinctions has been grossly underestimated due to a mathematical ''misdiagnosis'' and is likely to be 100 times greater than current estimates.
The study, led by Brett Melbourne of the University of Colorado, claims methods used to determine species at risk of extinction have overlooked a key factor random differences between individuals in a given population. These differences include physical size, sex ratios and behavioral variations that can influence survival rates and reproductive success.
''When we apply our new mathematical model to species extinction rates, it shows things are worse than we thought,'' Dr Melbourne said.
The International Union for Conservation of Nature currently estimates more than 16,000 species worldwide are threatened with extinction one in four mammals, one in three amphibians and 10 per cent of the world's birds.
Dr Melbourne said these figures should be ''revised upward by a large amount''.